Summary and Analysis of Comments
on THE
Notice of Proposed Rulemaking
for
Revised Gaseous Emission Regulations
for 1984 and Later Model Year Light-Duty
Trucks and Heavy-Duty Engines
July 1983
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Sources
Office of Air, Noise and Radiation
U.S. Environmental Protection Agency
-------
Summary and Analysis of Comments
on the
Notice of Proposed Rulemaking
for
Revised Gaseous Emission Regulations
for 1984 and Later Model Year Light-Duty
Trucks and Heavy-Duty Engines
July 1983
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Sources
Office of Air, Noise, and Radiation
U.S. Environmental Protection Agency
-------
Table of Contents
Page
I. Introduction . iii
II. List of Commenters iv
III. Analysis of Issues
A. Primary Issues 1
1. Technology/Standards 1
2. Useful Life 43
3. Alternative Cycles and Standards 72
4. Environmental Impact 118
B. Secondary Issues . 130
1. Deterioration Factors 130
2. Idle CO Test and Standards 134
3. Fuel Economy 140
4. Allowable Maintenance . 149
5. Minor Amendments to HDE/LDT SEA 159
6. Split Standards - Gasoline-Fueled vs.
Diesel Engines 181
7. Cold-Start Test Requirements . 188
8. Diesel Engine CO Measurement 196
9. Parameter Adjustment 197
10. Potential Impacts on Specific
Manufacturers 200
11. Transient Test Procedures 206
12. Possible "Migration" from Class IIB
to Class III 225
13. Diesel Engine Closed Crankcase
Requirements 230
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-ii-
Table of Contents (cont'd.)
Page
IV. Appendices
A. Draft Technological Feasibility from NPRM ... A1
B. Transient Test Study B1
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I. Introduction
On January 13, 1982, the Environmental Protection Agency
(the Agency) published a Notice of Proposed Rulemaking (NPRM)
in which the Agency considered revised gaseous emission
regulations for 1984 and later model year light-duty trucks and
heavy-duty engines. Although the major thrust of this action
was to propose non-catalyst emission standards for heavy-duty
engines, the Agency also requested and received comment on a
large number of other issues related to the 1984 emission
control requirements for light-duty trucks and heavy-duty
engines.
To seek further clarification and comment on issues raised
by the initial NPRM, several opportunities were offered for
comment, including a further request for comments published in
the Federal Register on March 12, 1982. A final rule was
published in January 1983. Also, to achieve final resolution
on the useful-life requirement, a further NPRM on the 1985
light-duty truck and heavy-duty engine useful-life requirements
was published in January 1983.
This document presents a Summary and Analysis of Comments
received in response to the NPRM and the subsequent requests
for comment mentioned above. The useful-life discussion
presented as Primary Issue 2 serves as the study of the
useful-life requirements discussed in the Federal Register
Notice of April L3, 1981. The transient test study undertaken
as a result of the same Federal Register notice is included as
Appendix B.
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-iv-
II. List of Commenters
1. American Motors Corporation (AMC)
2. Caterpillar Tractor Company
3. Chrysler Corporation
4. Cummins Engine Company
5. Engine Manufacturers Association (EMA)
6. Ford Motor Company
7. Freightliner Corporation
8. General Motors Corporation OGM)
9. U.S. Senator Gary Hart
10. Hino Motors, Limited
11. International Harvester Company (JHC}
12. League of Women Voters of Carson City, Nevada
13. League of Women Voters of the Doyleston Area
14. League of Women Voters of the United States
15. Mack Trucks, Inc.
16. Manufacturers of Emission Controls Association (MECA)
17. Mercedes-Benz of North America (MB)
18. Mrs. V, H. Worse
19. Motor Vehicle Manufacturers Association (MVMA)
20. National Association of Van Pool Operators (HAVPO)
21. National Automobile Dealers Association (NADA)
22. Natural Resources Defense Council (NRDC)
23. New York City League of Women Voters
24. Regional Air Pollution Control Agency, Dayton, Ohio
25. Frances Scherer
26. Toyota Motor Company
27. Western New York Allergy and Ecology Association
28. Volkswagen of America (VWoA)
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A. Primary Issues
1. Issue: Technological Feasibility
Summary of the Issue
This analysis addresses the technological feasibility of
emission standards for heavy-duty engines (HDEs) for 1985 and
later model years. Two separate analyses are contained
herein: an analysis and derivation of hydrocarbons (HC) and
carbon monoxide (CO) emission standards for 1985 which are
achievable without catalysts, and an analysis of the
feasibility of catalyst-based standards for 1987 and later
model years.
A. NON-CATALYST STANDARDS FOR 1985
Summary of the Comments/Synopsis of Events
There have been several iterations of EPA action and
public reaction as this issue has developed over time. For
purposes of clarity, a brief synopsis of significant events is
appropriate; public comments to each iteration will be
summarized as they chronologically occurred.
On January 21, 1980, EPA promulgated final regulations for
the control of gaseous emissions from HDEs applicable to the
1984 and later model years.[1] The regulations included the
new EPA transient test cycles, the full useful-life concept,
and statutory emission standards of 1.3 grams per brake
horsepower-hour (g/BHP-hr) HC, 15.5 g/BHP-hr CO, and 10.7
g/BHP-hr oxides of nitrogen (NOx).* Compliance with these
emission standards on the transient test almost certainly
requires the use of oxidation catalysts on heavy-duty gasoline
engines {HDGEs).
On April 6, 1981, the Vice President's Task Force on
Regulatory Relief announced that EPA would propose emission
standards for 1984 which would not require the use of
catalysts. It was intended that this action defer the capital
investments required for catalyst development, and thus provide
economic relief to an industry beset by recession and decreased
sales. On January 13, 1982, EPA officially proposed
non-catalyst emission standards of 1.3 HC/35.0 CO/lO.7 NOx for
1984 HDEs.[2]
The associated Draft Regulatory Analysis[3] tentatively
concluded that emission standards of 1.3 HC/35.0 CO were
feasible without cataiysts. The analysis discussed the
transient test in great detail, and presented modal emissions
All standards are based upon the EPA HDGE transient cycle.
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from 12 1979 model year HDGEs. Emission levels for current
technol'ogy were discussed, as were the emissions impact of
specific operational modes of the transient test. By comparing
low. to high emitting engines and by identifying specific
technologies and calibrations, EPA made the judgment that
1.3/35.0 appeared feasible for 1984 non-catalyst HDGEs.
In public comments to the Notice of proposed Rulemaking
(NPRM) received by April 1982,[4,5] only Ford Motor Company
(Ford) and General Motors (GM) submitted transient test
emissions data. Chrysler and international Harvester Company
(IHC) did not comment on technological feasibility, and in
fact, indicated that they were leaving the HDGE market for
reasons unrelated to these regulations. (Both Chrysler and IHC
have since indicated that they may reverse these decisions.)
In its comments, Ford stated its position as follows:
"Ford believes that its recommended 3.3 HC and 42 CO
g/BHP-hr standards for the 1985 model year HDGEs represent
the lowest levels achievable without unreasonable
sacrifices in performance, fuel economy, or driveability."
General Motor's comments stated that:
"lieview of available 1984 prototype HDGE development data
indicated that most GM HDGEs could achieve low-mileage
emission levels of approximately 2.0 HC and 32 CO
g/BHP-hr."
General Motors subsequently recommended emission standards
of 2.9 g/BHP-hr HC and 43.0 g/BHP-hr CO, on the basis of
increased certification deterioration factors and assumed
production variability. GM also argued that standards of 3.5
g/BHP-hr HC and 70 g/BHP-hr CO were justified on the basis of
air quality needs, fuel economy, and cost. in comments and
later discussions, GM also raised the point that the emission
control strategies required to reduce HC and CO emissions to
EPA's proposed standards could severely degrade engine
durability. GM claimed that the need for full-power mixture
e'nleanment and increased oxidation of pollutants in the exhaust
system will raise in-cylinder and exhaust system temperatures
to excessive levels. GM said that this will not necessarily be
seen on EPA's transient test procedure, but more than likely
will be seen in severe in-use applications for engines
calibrated to meet EPA's proposed requirements.
Emissions data for 1984 prototype HDEs, as submitted by GM
and Ford in April of 1982, are listed in Table 1-1.
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Table 1-1
Manufacturers' 1984 Prototype Heavy-
Duty Engine Data (submitted by April 1982)
Engine
Emission
q/BHP-hr*
BSFC
Manufacturer
Displacement
Control System
HC
CO
NOx
lb/BHP-hr
Ford
4.9L
AIR/EGR/EFE
1.66
23.2
7.68
0.560
Ford
6.1L
AIR/EGR
2.33
28.8
7.25
0.654
Ford
7.0/7.5L
AIR/EGR
2.21
24.3
4.82
0.633
GM
292 in3
AIR/EGR
1.65
17.42
6.52
--
GM
350 in3
AIR/EGR
1.76
25.07
5.25
GM
366 in3
AIR/EGR
1.33
20.19
6.91
--
GM
454 in3
AIR/EGR
0.90
20.93
7.42
—
EPA cycle based.
-3-
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In reviewing these comments, EPA staff felt that
additional engineering data were required to determine the
lowest emission standards achievable without catalysts.
Specific requests for more detailed information were made to
HDGE manufacturers on June 17, 1982;[6] Ford provided
additional engineering data, GM provided a more detailed
qualitative discussion and emission data {see Table 1-2) but
declined ;to submit detailed engineering data, and Chrysler and
IHC wer£ unable to provide any additional data or information.
At a meeting with EPA staff on January 28, 1983,
representatives of GM again made the claim that 1.3/35.0
non-catalyst emission standards would adversely affect engine
durability and fuel economy.
In a Federal Register notice of January 12, 1983, EPA
officially delayed the 1984 model year emission requirements
until 1985. This revision of the 1985 standards was justified
on the basis of Leadtime,* economics,* and the number of other
issues yet to be resolved (i.e., alternative test cycles,
useful life, etc.].
Reviewing all comments and data available at the time, and
taking into account the additional year of development
leadtime, EPA then, analyzed the level of non-catalyst emission
standards achievable for 1985. This analysis [8] went
hand-in-hand with an EPA staff paper[7] in which both short and
long-term strategies for the control of HDGE emissions were
discussed. The staff paper, which was released for public
comment on March 16, 1983, developed a control scenario whereby
lighter heavy-duty gasoline trucks (HDGTs) would be equipped
with catalysts in the 1987-88 time frame, and heavier gasoline
truck engine standards would remain at non-catalyst levels.**
At the same time, the staff paper summarized EPA's most recent
analysis of 1985 standard feasibility, which had recommended
non-catalyst standards of 2.5/35.0 g/BHP-hr.
This feasibility analysis,[8] the summarized results of
which were discussed at an April 6, 1983 Public Workshop, was
also distributed for public comment on April 12, 1983. The
analysis recommended that non-catalyst emission standards of
2".5/35.0 g/BHP-hr be promulgated for 1985. This recommendation
revised EPA's earlier conclusion that a 1.3 g/BHP-hr HC was
feasible for 1984 without catalysts.
* See appendix, Chapter 3 of the Transient Test Study.
** See the POST-1985 EMISSION STANDARDS section of this issue.
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Table 1-2
Additional Emission Data
Provided by GM in August of 1982[5]
Low-Mileage Emissions*
Enqine
HC
CO
NOx
BSFC
GM 292
2.17
24.9
6.80
.639
GM 350-2V
1.57
28.2
6.11
.604
GM 350-4V
1.99
27.2
5.14
.649
GM 366
.75
17.9
3.57
.582
GM 454
1.01
22.2
4.28
.666
EPA cycle-based g/BHP-hr. GM claimed that these data are
representative of heavy-duty gasoline engine emission
control systems and calibrations which, in August of 1982,
were believed to be "at least plausible for production."
None of these engine configurations had been durability
tested, but all. had been driven in a small sample of
vehicles and had been determined to provide commercially
acceptable performance and driveability.[5]
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EPA's more recent conclusion that .the non-catalyst HC
standard must be relaxed was based upon several
considerations. A review of the actual development data
submitted by Ford and GM in April 1982 (see Table 1-1)
indicated that substantial progress had been made in reducing
emissions. However, all but one engine family were still well
above the low-mileage target emission levels needed to assure
compliance with a 1.3 g/BHP-hr HC standard. (All engine
families were very close to the low-mileage target level for CO
more than two years before required compliance, hence no
relaxation of the CO standard was recommended.) EPA's analysis
then discussed the remaining technology which could be applied
to reduce HC emissions further. Since only Ford supplied
detailed engineering data in response to EPA's June 17, 1982
request, only an analysis of Ford's product line was possible.
(Since GM's engines in Table 1~1 all exhibited HC emission
rates less than most Ford engines, it was judged that GM would
have no problem complying with an HC emission standard based
upon Ford's higher emitting engines.) Using data provided by
Ford, EPA concluded that further reductions in HC were
certainly possible, and that compliance with a 2.5 g/BHP-hr HC
standard in 1985 would be possible even for Ford's highest
emitting engine. HC standards less than 2.5 g/BHP-hr were
considered, but were rejected on the basis of reasonable risk
of non-compliance and fuel economy penalties for higher
emitting engines. In summary, 2.5/35.0 were recommended as
reasonable interim emission standards.
In comments[5] received by May 6, 1983, the conclusions
and methodology of EPA's latest feasibility analysis[8] were
again disputed. These comments are summarized below for each
commenter.
Chrysler
Chrysler again commented that it was in no position to
recommend specific interim standards, primarily because its
transient test facility was not yet operational. Based upon
testing performed for it under contract, however, Chrysler did
not believe that the 35.0 g/BHP-hr CO standard was feasible
even with a catalyst. Chrysler recommended continued provision
of the 9-mode steady-state option until 1986.
Engine Manufacturer's Association (EMA)
The EMA and its member companies have not disputed the
feasibility of the 1.3/35.0 g/BHP-hr standards for heavy-duty
diesel engines (HDDEs).
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Ford
Ford provided a comprehensive review of the emissions
status of its HDGE product line. Ford>s data showed that
significant progress has been made in reducing emissions.
However, Ford disputed EPA's feasibility analysis,
characterizing it as overly optimistic. "EPA's suggestion that
manufacturers not only can meet 2.5/35.0 but can also achieve
substantial further reductions is overstated." Ford also
argued that "EPA has overestimated the capabilities of some
heavy-duty engines," notably Ford's 6.1L-4V (Ford's largest
seller and occupant of the heaviest gasoline vehicle weight
classes). The major problem associated with feasibility,
according to Ford, is not so much the effectiveness of
technology but rather the relatively low target levels which
are forced upon a manufacturer by the full useful-life and
Selective Enforcement Audit (SEA) requirements. Ford
recommended half-life standards of 2.19/42.6 based upon the
MVMA cycle; according to Ford, these are equivalent to
full-life EPA cycle standards of 3.07/47.8.
General Motors
General Motors vigorously disputed the conclusions of
EPA's feasibility analysis, characterizing the analysis as
"entirely inadequate," and mostly "guesswork." GM insisted
that EPA's engineering judgment was based upon limited and
outdated emission data, very few research studies, and limited,
incomplete data supplied by manufacturers. GM also criticised
EPA for "engineering on paper," for failing to construct and
evaluate through testing, any engine conforming to EPA's design
recommendations, and for failing to generate any current data.
General Motors qualitatively discussed several engineering
aspects of achieving low levels of HDGE emissions without
catalysts. GM also discussed durability, driveability, and
fuel economy problems associated with "unreasonably stringent
standards." in GM's opinion, forced compliance with the 35.0
g/BHP-hr CO standard would preclude the production of
reasonably durable engines. indeed, GM argued that the poor
performance of engines produced under these emission
constraints would invite tampering in the field.
General Motors questioned EPA's apparent policy of
establishing stringent interim standards, especially given the
major changes occurring in the 1987-8B timeframe, the "risk to
the heavy-duty industry," and "the lack of demonstrated
feasibility." GM recommended half-life non-catalyst emission
standards of 2.9/43.0 (EPA cycle) for 1985.
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With respect to data, GM submitted a large confidential
discussion of various aspects of its development work.
Included were qualitative discussions of GM's calibration
strategies and hardware for complying with 1.3/35.0 g/BHP-hr
standards, qualitative discussions of GM's engine durability
experience, a description of GM's in-house durability test
procedures, comparisons of 1983 versus 1985 prototype timing
and air/fuel (A/F) calibrations, actual test reports from
characterizations of wide-open throttle (WOT) timing versus
detonation requirements, on-road fuel economy data, and actual
test reports from exhaust system temperature and durability
studies.
On the other hand, no new emission data were submitted by
GM; the latest data indicating the position of GM's product
line with respect to compliance was that submitted by April and
August of 1982 {see Tables 1-1 and 1-2) . GM went on to
characterize the April 1982 data as being unrepresentative of
its true compliance capability, having been acquired long
before subsequent testing discovered durability problems.
Furthermore, GM stated that its test experience and comments
only address the feasibility of the 1.3/35.0 standards. GM
claimed that it had only just begun to evaluate the
implications of the 2.5/35.0 standards. Nevertheless, GM
recommended that EPA promulgate half-life standards of 2.9/43.0
(EPA cycle) g/BHP-hr for 1985.
Analysis of Comments
Overview
This analysis will develop and recommend non-catalyst
standards for 1985 and later model year HDGEs. Aside from the
specific hardware and applicable emission control techniques to
be addressed, it is equally important to address the effect of
other factors on the stringency of the interim emission
standards. The most important of these other factors are the
full useful-life concept, the SEA requirements, and the
correlation between the EPA and MVMA test cycles. These issues
will be discussed first, because of their inherent impact on
standard stringency.*
The relationship of two of these factors to low-mileage
emission targets and emission standards is typically
expressed as:
[Emission Standard - DF] = Low-mileage target.
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The analysis will then review the status of the HDGE
manufacturers with respect to current emission levels of their
"best effort" engines; where possible. As in earlier analyses,
judgments will be made whether further reductions can be made
for the 1985 model year.
Deterioration Factors
Manufacturers are required to correct "low-mileage"
emission levels from certification engines for expected in-use
deterioration. Current requirements, and those applicable for
1985, require that deterioration be assessed in an additive
fashion. Current deterioration factors (DFs) have largely been
derived from durability testing performed on engine
dynamometers. Very little, if any, data exists on the degree
of deterioration which actually occurs in use. Dynamometer
durability testing results have never been validated, and there
is substantial uncertainty as to the magnitude of true in-use
dfs for all hdes.
On the other hand, the process of compliance in 1985 will
be based upon dfs derived and supplied by the manufacturer in
whatever manner they deem appropriate. Techniques of DF
derivation can range from simple engineering judgment to
continued use of dynamometer testing to actual in-use tests.
Given the lack of an officially imposed method, one would
expect manufacturers to base their DF determinations upon past
practice and experience.
Certification dfs for HDGEs have typically been quite
small. Table 1-3 presents a summary of official certification
DFs for Ford's and GM's HDGEs for the 1983 model year. in
almost all cases, emissions decreased after completion of
durability test runs on the engine dynamometers. Substantial
changes, however, are being made to engine hardware for the
1985 model year. This new hardware will also be required to
maintain compliance for a full useful life (110,000 miles), as
opposed to the previous half-life (50,000 miles) requirement.
Therefore, the dfs in Table 1-3 may be somewhat less than dfs
derived and used for 1985.
in past analyses, EPA has converted from half- to
full-life DFs by assuming linear deterioration (i.e, the
full-life DF is equal to the half-life DF multiplied by
110,000/50,000, or 2.2). This methodology is straightforward,
and fits the general trend of deterioration observed in
dynamometer testing of non-catalyst engines. While EPA has
confidence in this adjustment, assessing the deterioration
rates of new engine hardware not yet in production is more
problematic.
Based upon current prototypes, 1985 HDGEs will likely be
equipped with the following hardware: large dual air pumps,
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Table 1-3
1983 Model Year Certification
Deterioration Factors (DFs) for Ford and GM HDGEs
Certification DFs*
Manufacturer/Engine Family HC CO
Ford 4.9L "Q" 0.00 0.00
Ford 6.1L "E" - 2V 0.00 1.91
Ford 6.1L "E" - 4V 0.00 1.91
Ford 7.0L "E" 0.00 0.00
Ford 7.5L "E" 0.00 0.00
Ford 5.8L (W) "E" 0.00 0.48
GM DGM07.0ABB4:
- L86 (366 CID) 0.00 0.00
- L43 (427 CID) 0.00 0.00
GM DGM07.4ABB9:
- LF8 (454 CID) 0.00 0.00
GM DGM04.8ABA6:
- L25 (292 CID) 0.00 0.00
GM DGM05.7ABB9:
- LF5 (350 CID - 2V) 0.00 0.00
- LS9 (350 CID - 4V) 0.00 0.00
Additive g/BHP-hr, half-life basis.
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EGR, early fuel evaporation systems, heated air intake systems,
and automatic chokes. Carburetor and ignition timing
calibrations will be different from current models, as will
manifold designs and air injection systems. in-cylinder and
exhaust system temperatures will be hotter than those of
current engines because of leaner mixtures and increased
thermal reaction. as a total package, these modifications are
uncharacterized in heavy-duty engine applications with respect
to deterioration and long-term performance. Given the
significant changes from 1984 to 1985, it is reasonable to
expect that manufacturers will run at least some dynamometer
durability tests out to the full useful-life equivalent of
3,300 hours.
Quantification of expected deterioration is by necessity
somewhat speculative, but there are a number of reasons why
1985 DFs should not be exceptionally high:
1. No inherent increase in deterioration rates should
be expected from recalibrations of ignition timing or
carburetors. Deterioration rates of this hardware have been
previously established, and simple changes to timing settings
or fuel flow rates should not alter the functional durability
of the hardware.
2. Catastrophic or significant causes of deterioration
to minor components will be identified during accelerated
durability testing, at which time corrective redesign can take
place.
3. If problems arise with component-related durability,
especially during dynamometer testing corresponding to the
second half of the useful life, new maintenance provisions can
be specified to alleviate the problem.
4. Prototype air injection systems are merely larger
versions of existing systems whose durability performance have
already been characterized. Other changes simply represent
changes to static piping and manifolds; these hardware
experience minimal emission-related deterioration.
5. Finally, most of the hardware new to HDGEs have
already been successfully used on production LDVs and LDTs for
several years. EPA expects the manufacturers to have acquired
considerable experience with the design, maintenance, and
in-use durability of such hardware. This experience is
directly relatable to HDGEs.
Given the above, and given the dfs presented in Table 1-3,
EPA does not expect large dfs to be used or needed for 1985.
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Referring to Table 1-3, only two engine families exhibited
a non-zero CO DF for 1983 (the Ford 6.1L and 5.8L). EPA does
not expect CO deterioration rates to be significantly different
from 1983; CO emission control is primarily a function of
leaner carburetor calibration and improved air injection,
neither of which should affect durability to any great extent.
For purposes of this analysis, EPA will use the worst case DF
from 1983 (1.91 for the Ford 6.1L), corrected from half- to
full-life (i.e., 1.91 multiplied by 110,000/50,000 or 2.2 to
equal 4.20).
Quantification of HC deterioration is more speculative.
All 1983 Ford and GM engine families exhibited HC DFs of 0.00
or less, but there is some reason to believe that HC DFs may
increase in 1985. Cold start emission control apparatus is
new, as would be more elaborate ignition timing controls (if
used). These systems will primarily affect HC emissions. On
the other hand, systems of this type have already been used for
several years on production LDVs and LDTs, and EPA presumes
that the manufacturers have well characterized. their
performance. For purposes of this analysis, EPA will use the
same additive DF used in the earlier analysis, [8] a DF of .25.
This is likely to be a representative DF, given the performance
of current engines, the existing experience with such equipment
on LDTs and LDVs, and EPA's assumption of a moderate increase
in DFs for 1985.
SEA Requirements
SEA testing requirements are scheduled to take effect in
the 1986 model year. Therefore, a manufacturer cannot be
subjected to the jeopardy of failing a production line audit
until 1986. For this reason, it is entirely reasonable to
ignore SEA requirements in establishing emission target levels
for 1985. On the other hand, it is also reasonable to expect
that a manufacturer would wish to conclude development work
prior to 1985, and rely upon carryover for the next year to
avoid continued recertification expenses. This feasibility
analysis will include the effect of SEA requirements in
establishing feasible emission standards for 1985, since
recertification in 1986 would not be desirable from the
manufacturers' standpoint. However, in the event that one or
two engines may appear to be having difficulty in achieving
SEA-based low-mileage target levels for 1985, EPA cannot ignore
the additional flexibility provided manufacturers by the
effective relaxation of low-mileage target levels afforded by
EPA's deferral of SEA requirements.
Production line emission variability is fairly well
characterized. EPA's earlier analysis[8] and Ford's May 6,
1983 comments[5] used numerical values of 1.136 and 1.200,
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respectively, for HC, and 1.266 and 1.300, respectively, for
CO. (GM has previously used a 40 percent AQL factor of 1.10
for all gases.[5]) EPA's and Ford's values are essentially in
agreement; for purposes of this analysis, arithimetic averages
of Ford's and EPA's numbers will be used (i.e., 1.168 for HC
and 1.283 for CO), and represent conservative values in EPA's
judgment. For worst case engines, however, a value of 1.000
would be available for the 1985 model year.
Alternative Test Cycles
EPA's earlier analyses[3,7,8,9 ] were all based upon EPA
cycle test results, and the emission standards discussed were
also based upon the EPA cycle. All of the latest."best effort"
emission data, however, is MVMA cycle based. For purposes of
this analysis, MVMA cycle-based standards will be developed
from this "best effort" data. For purposes of comparability
with previous analyses, equivalent EPA cycle-based standards
will also be presented.*
Only Ford gave EPA specific information on the current
emissions status of their product line. As in its earlier
analysis,[8] EPA will evaluate the feasibility of emission
standards for HDGEs based largely upon Ford's data. In the
absence of any specific emissions data to the contrary, and by
reviewing the latest GM emission data made available to. EPA in
August of 1982, EPA will assume that the emissions capabilities
of GM's engines are not substantially different from Ford's.
The emissions capabilities of Chrysler's and IHC's engines are
unknown, however, the necessary technologies are widely
available and well understood. EPA does not expect the
emissions capabilities of Chrysler's or IHC's engines to be
fundamentally different from those of Ford or GM.
Current Status of HDGE Emission Levels
Tables 1-4, 1-5, and 1-6 present EPA's evaluation of
Ford's "best effort" data; Table 1-5 also includes GM's most
recent data. Clearly, significant improvements have been made
since 1979 and earlier model years (see Figures 1-1 and 1-2).
Using Ford's recent MVMA cycle-based low-mileage results, these
levels have been converted to equivalent emission standards,
both in terms of the MVMA cycle and the EPA cycle (see Tables
* Equivalent EPA cycle-based emissions will be based upon
the following equations (derived in Issue A.3. of this
Summary and Analysis of Comments):
HC: MVMA = .886 (EPA) - 0.318
CO: MVMA = 1.0 3 (EPA) - 4.04
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Table 1-4
Review of Ford's "Best Effort" Data,[5] Estimated
Current Attainable MVMA Cycle-Based Emission Standards*
May 1983 Data
Ford
Engine Model
4.9L-1V
6.1L-2V
6.1L-4V
7.0L-4V
7.5L-4V
Low-Mileage
Emission Results*
HC
CO
1.21(1.72) 25.0(28.2)
1.08(1.58) 23.4(26.6)
1.70(2.28) 28.5(31.6)
1.50(2.05) 17.7(21.1)
1.36(1.89) 23.6(26.8)
Equivalent
Deteriorated
HC Emission
Standard*
1.66(2.26)
1.51(2.09)
2.24(2.91)
2.00 (2.65)
1.84(2.46)
Equivalent
Deteriorated
CO Emission
Standard*
36.3(40.4)
34.2(38.4)
40.8(44.7)
26.9 (31.3)
34.5(38.6)
MVMA cycle based, g/BHP-hr; the numbers in parenthesis are
EPA cycle based, g/BHP-hr.
-14-
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Table 1-5
Currently Attainable
EPA Equivalent Emissions Standards
Engine Family
Equivalent, Deteriorated
EPA Cycle-Based
HC Emission Standard*
Equivalent, Deteriorated
EPA Cycle-Based
CG Emission Standard*
May 1983 Data (derived from Table 1-4)**
Ford 4.9L-1V
Ford 6.1L-2V
Ford 6.1L-4V
Ford 7.0L-4V
Ford 7.5L-4V
2.26
2.09
2.91
2.65
2.46
40.4
38.4
44.7
31.3
38.6
August 1982 Data (derived from Table 1-2)
GM 292
GM 350-2V
GM 350-4V
GM 366
GM 4 54
2.78
2.08
2.57
1.13
1.43
36,
40,
39,
27,
32.7
April 1982 Data (derived from Table 1-1)
Ford 4.9L
Ford 6.1L
Ford 7.0/7.5L
GM 292
GM 350
GM 366
GM 454
2.19
2.97
2.83
2.18***
2.31***
1.80***
1.30***
34.0
41.2
35.4
26.5***
36.4***
30.1***
31.1***
* EPA cycle-based, g/BHP-hr, assumes deterioration and
includes SEA requirements.
** Calculated by first correcting MVMA to EPA low mileage
emissions, then adjusting for SEA and deterioration.
*** These emission levels were claimed by GM in May of 1983 to
have promoted unacceptable engine durability and
performance, and were reported to EPA before discovery of
such problems.
-15-
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Table 1-6
Compliance Ability of Ford's
Product Line at Various Levels of EPA
Cycle-Based Emission Standards (May 1983 data)
EPA Cycle-Based
Emission Standards Number of Engine Models
HC CO in Compliance by May 1983*
1.3 35.0 0 out of 5
2.5 35.0 1 out of 5
2.5 40.0 3 out of 5
2.6 40.0 4 out of 5
2.9 45.0 5 out of 5
Assumes deterioration; includes 1986 SEA requirements.
-16-
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Figure 1-1
CO Emissions (EPA Cycle-Based) from Ford HDG Engines
(Note: Engines of similar displacement over time are
considered to be in the same "familv.")
i
Measured
BSCO
Emissions
(g/BHP-hr)
250
1969 Baseline Average
Y (Uncontrolled]^
Ford Engine "Fami"
~ = 4 . 9 L
A = 6 . 1 L
= 6 . 6 L
X = 7.0/7.5L
~ = Mean of al
"Families"
I 363
I 373
1973 Baseline Average
1979 Baseline Average
_ 1 9 85 Non-Catalyst Standard
Statutory Standard
j
I 373 I3BE 13B3
Model Year
-------
Figure 1-2
i
i—
CO
I
Measured
BSiiC
Erai ssions
(g/BUP-hr)
IIC Emissions (EPA Cycle-Based) from Ford HDG Engines
(Note: Engines of simialr displacement over time are
considered to be in the sa^oe "family.")
Ford Engine "Family"
Model Year
-------
1-4 and 1-5). Table 1-6 summarizes the ability of Ford's
engines, in May of 1983, to comply with a variety of potential
emission standards.
Tables 1-5 and 1-6 indicate that only two of Ford's five
engine models would today exceed an HC standard (EPA cycie
based) of 2.5 g/BHP-hr (and one marginally so), whereas four
out of five would exceed the 35.0 g/BHP-hr CO standard. An
important observation to make is the fact that very little has
changed in Ford's compliance ability between April 1982 and May
1983 (see Table 1-5). Ford made the statement in their
comments of May 6, 1983 that significant progress had been made
relative to Ford's reported status of April 1982. However,
EPA's present analysis indicates that much of the reported
progress was illusory, arising primarily from a change in test
cycles. (The April 1982 data were EPA cycle-based; the May
1983 data were MVMA cycle-based.)
Based solely upon Ford's May 1983 data, the current
critical range of feasibility apparently lies between 2.5-2.6
g/BHP-hr HC and 35.0-40.0 g/BHP-hr CO (EPA cycle based).
Assuming for the moment that there' is little practical
difference between a 2.5 and 2.6 HC standard, then relaxing the
proposed CO standard of 35.0 to 40.0 would allow all but one of
Ford's engines to comply with 1985 requirements in May of 1983,
taking into account deterioration and 1986 SEA requirements for
1985 . Reviewing GM's latest data (presented in Table 1-5),
this relaxation would also allow all but one of GM's engines to
comply, even if no improvement in emission levels have been
made since August of 1982.
1985 Standards Derivation
EPA's draft feasibility analysis[8] attempted to evaluate
the detailed calibrations, hardware, and associated emission
levels of Ford's April 1982 engines. using these facts as
starting points, EPA surmised how additional emission
reductions could be made for the few engines which the April
1982 data indicated actually required further work to meet 2.5
g/BHP-hr HC and 35.0 g/BHP-hr CO (see Tables 1-1 and 1-5).
Emission reductions were predicted based upon established
principles of emissions engineering, whereby given changes of
calibrations produce predictable trends in emissions.
Both Ford and GM took issue with EPA's analysis.
Criticism of EPA abounded, but no approaches for further
emission control were recommended as having promise. GM
harshly criticized EPA for drawing conclusions from a limited
data base, despite its refusal to provide EPA with specific
-19-
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calibration information. Ford was less critical than GM,
discussing several of EPA's evaluations and indicating where
Ford thought they were incorrect or why they would prove
ineffective. Despite Ford's presentation on the emissions
status of their product line, EPA still has only generalized
information as to the specific emission control techniques
attempted, which were discarded, and which remain available
(with and without trade-offs). Furthermore, without specific
engine calibration information it is difficult for the Agency
to identify which levels of emission standards represent the
most stringent standards possible without unreasonable impacts
on cost or fuel economy, as EPA is required by law to
promulgate. Commenters are correct in maintaining that EPA is
not close enough to engine development efforts to anticipate
engine specific problems which arise as each control technique
is applied to each engine. For this reason alone, the
manufacturers are responsible for providing EPA with the
detailed, unbiased information it needs to make reasoned
decisions.
Without such information, EPA can only review the best
available data, and make a judgment as to what represents
reasonable interim standards, given the state of current engine
development and given the remaining leadtime until 1985.
As shown in Table 1-6, only one of Ford's engines would
significantly exceed an HC standard of 2.5 g/BHP-hr. The
remaining engine, the 6.1L-4V, would require a 16 percent
reduction in low-mileage emissions to meet the 2.5 standard
(see Table 1-7). If Ford takes advantage of the certification
flexibility provided by EPA for 1985 (SEA requirements do not
apply), the 6.1L-4V would already meet a 2.5 standard if only
deterioration is included with the low-mileage emissions to
determine compliance, in short, one extra year of leadtime is
available, if necessary, for attaining what appears to be a
modest reduction in HC emissions. EPA will not speculate as to
which technologies will be used to achieve the reduction,
although in the worst case ignition timing retard is
available. More importantly, EPA cannot allow the
technological laggard to set the pace for standard setting; to
do so surrenders the gains already achieved with the majority
of engines, and does little to motivate a manufacturer to lower
emissions from its engines.
To some extent, the same argument holds true in
determining a feasible CO standard. However, as shown in Table
1-6, the majority of Ford's product line will require
additional work to achieve the 35.0 g/BHP-hr CO standard. Some
reduction in low-mileage emissions will be necessary for four
out of five engines, including a substantial reduction (26
percent) for the 6.1L-4V family (see Table 1-7). Given the
-20-
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Table 1-7
Percentage Reductions in low Mileage Target (LMT)
Emissions Required to Comply with Emission standards of
2.5 g/BHP-hr HC and 35.0 g/BHP-hr CO (EPA cycle based)
Required HC Required CO
Engine Family LMT Reductions (%) LMT Reductions (%)
Ford 4.9L-IV*
0
16
Ford 6.1L-2V*
0
10
Ford 6.1-4V*
16
26
Ford 7.0L-4V*
5
0
Ford 7.5L-4V*
0
11
GM 292**
9
2
GM 350-2V**
0
13
GM 35C-4V**
1
10
GM 366*+
0
0
GM 454**
0
0
* May, 1983 data.
** August, 1982 data.
-21-
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industry's claims of decreased engine durability with further
enleaned fuel mixtures at WOT, and given the remaining
leadtime, there appears to be some risk in a 35.0 g/BHP-hr CO
standard. if, on the other hand, the emissions from Ford's
worst emitter (again the 6.1L-4V) were to be reduced to the
level of the remainder of Ford's fleet, an emission standard of
40.0 g/BHP-hr would be required. Again, EPA rejects the idea
that the technological laggard set the pace of emissions
reduction; therefore, a standard greater than 40.0 g/BHP-hr
would be unjustified.
Selecting a CO standard between 35.0 and 40.0 g/BHP-hr
then becomes an exercise in evaluating trade-offs.
Promulgation of 35.0 g/BHP-hr, or any standard which requires
the majority of the product line to achieve further reductions,
will increase the risk of durability problems, and at the same
time direct development efforts away from the 1987 standards.
Requiring the highest emitters to achieve further reductions,
however, is both appropriate and necessary to retain reductions
already achieved. From Table 1-5, EPA notes that the majority
of Ford's engines (according to the latest data) lie at the
high end of the 35.0-40.0 g/BHP-hr range.
EPA does not believe that compliance with a 35.0 g/BHP-hr
CO standard is infeasible. However, some additional
development work would be necessary for four of Ford's five
families, and significant work for one family. Given the fact
that some development work is still required to meet both the
2.5 g/BHP-hr HC standard and a 40.0 g/BHP-hr CO standard, given
EPA's desire not to preempt significant development efforts
from the 1987 model year, given the fact that many of the
engines for which data is currently available exhibit CO
emissions closer to 40.0 g/BHP-hr than 35.0, and given the risk
to engine durability entailed in meeting a 35.0 g/BHP-hr CO
standard within short leadtimes, EPA believes that 40.0
g/BHP-hr would be a reasonable non-catalyst CO standard for
1985.
EPA's evaluation of the latest GM data leads it to the
same conclusions. as can be seen in Table 1-5, GM's August
1982 data indicates that only a single engine would
significantly exceed standards of 2.5/40.0, and it would only
exceed the 2.5 HC standard. GM has repeatedly expressed
concern about the durability implications of stringent
non-catalyst CO standards, as noted in Table 1-7, some of GM's
engines still require reductions in low-mileage CO emissions to
meet a 35.0 g/BHP-hr standard. However, the lack of specific
calibration information for GM's engine has made EPA's review
of the reasonableness of GM's claims difficult, at best. (For
example, EPA would not consider durability data taken on
engines with WOT A/F calibrations leaner than stoichiometry to
be at all representative; such calibrations would be
-22-
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unnecessary for compliance and understandably severe on
durability.) EPA notes that GM's criticism of EPA's earlier
feasibility analysis only addressed GM's concern with complying
with 1.3/35.0 standards. The latest GM and Ford data indicate
that low-mileage compliance with standards of 2.5/40.0 g/BHP-hr
represents no problem whatsoever for almost all engine
families; the feasibility issue essentially breaks down to the
level of emission standards which would not degrade engine
durability or performance. EPA believes that relaxation of the
proposed 1.3 HC standard to 2.5 will preclude the need for
substantial ignition timing retard, both preserving fuel
economy and precluding increased exhaust temperatures. EPA
also believes that relaxation of the proposed 35.0 CO standard
to 40.0 will also preclude the need for a/F calibrations lean
enough to promote excessively high temperatures and durability
problems. EPA bases these judgments on the current performance
of Ford's product line, upon Ford's claims that these emission
levels will not impair engine durability, upon GM's own test
data, and upon the lack of GM's comments and data to the
contrary for engines designed to meet emission standards at
these levels.
Conclusion
Revised gaseous emission standards of 2.5 g/BHP-hr HC and
40.0 g/BHP-hr CO (or 1.9 g/BHP-hr HC and 37.1 g/BHP-hr CO based
upon the MVMA cycle) are feasible without catalysts, will not
degrade engine performance or durability, and therefore should
be promulgated for the 1985 model year.
B. POST-1985 EMISSION STANDARDS
Summary of Comments/Synopsis of Events
Soon after the decision was made to propose non-catalyst
standards for the 1985 model year, EPA began evaluating when
further progress towards the statutory standards would be
appropriate for gasoline engines. it is generally accepted
that compliance with the statutory 1.3 HC/15.5 CO standards
will require oxidation catalysts. (Diesel engines easily
comply with the statutory HC and CO standards.)
EPA has never altered its conclusions of January 21,
1980[1,9] that catalysts are ultimately feasible for use on
HDGTs. The i justification for deferring catalyst-based
standards beyond 1984 was based principally upon economic
grounds and leadtime concerns, not technical feasibility.
on March 16, 1983, EPA distributed a staff paper[7] for
public comment, and subsequently held a Public Workshop on
-23-
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April 6, 1983. The staff paper presented options for the
long-term control of HC and CO emissions from heavy-duty
trucks. The major provision of the recommended option was that
HDGTs would be split along traditional class lines. vehicles
up to 14,000 lbs. gross vehicle weight (GVW) would be required
to meet statutory standards (and thus have catalysts); all
heavier gasoline vehicle engines would continue to meet
non-catalyst standards. This approach attempted to capitalize
on the transferability of light-duty truck (LDT) catalyst
technology to the largest fraction of HDGTs (the lighter
classes), while acknowledging the decreasing number of heavier
HDGTs on which catalyst application would be most expensive (on
account of the need to design increased survivability into
catalyst systems used in the more extreme heavier truck
environment). in short, emission reductions were hoped to be
achieved in the most cost-effective fashion. The suggested
implementation date for this strategy was the 1987-88
timeframe. Public comments on the staff paper were solicited
and accepted up until May 6, 1983.
prior to the May 6 close of comments, GM advanced an
alternative approach at an April 13, 1983 meeting with EPA
staff.[5] GM proposed that most* HDGTs under 10,000 lbs. GVW
("light heavy-duty vehicles") be required to meet emission
standards similar to those required for LDTs, and be certified
on the light-duty chassis dynamometer test procedure. Vehicles
above 10,000 lbs. would continue to have their engines
certified on EPA's heavy-duty engine test at non-catalyst
emission levels. GM proposed that the scenario take effect in
1987 .
Public comments received by May 6, 1983[5] addressed both
the EPA and GM scenarios and are summarized by commenter below.
Chrysler
Chrysler cannot support the GM proposal, because of the
proposed more stringent standards for LDTs below 6,000 lbs. GVW
and proposed relaxation for LDTs between 8,500 and 10,000 lbs.
GVW. Chrysler also opposes the creation of the light
heavy-duty class, arguing it would require an additional test
fleet for durability testing, thereby increasing costs.
Chrysler also claimed that EPA's engine dynamometer test
is not representative of vehicles less than 10,000 lbs. GVW.
Chrysler implied that another test would be better, but did not
specify any particular test.
Some exemptions would be allowed on the basis of larger
frontal area, etc.
-24-
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Ford
Ford argued that catalysts are not feasible for all
trucks, but may be feasible on trucks in. the 8,500-14,000 lb
category. Ford argued that catalyst standards should not be
implemented before 1988, because of production leadtimes and
the required 4-year leadtitae provisions of the Clean Air Act.
Ford suggested that the heavy-duty class be split at
10,000 lbs., primarily because there are not many class III
trucks,. Ford did not disagree, however, with EPA's concern
about potential migration, should HDTs be split at 10,000 lbs.
indeed, if EPA does split HDTs at 14,000 lbs., Ford recommended
specific vehicle types for exemption. These vehicles are those
which see the most severe operation, and thus, would be those
vehicles most difficult to equip with durable catalysts. Ford
also agreed with GM that the LDT chassis test procedure would
be appropriate for trucks under 10,000 lbs. GVW. Ford urged
EPA to consider this testing alternative seriously.
With respect to catalyst feasibility and the feasibility
of the 15.5 g/BHP-hr CO standard, Ford argued that temperatures
above 1,600°F will cause thermal degradation of the catalyst.
Catalyst protection systems are possible, but an
overtemperature protection system of air injection cutoff at
full load also cuts off CO control at its most significant
mode. This trade-off between catalyst durability and CO
control has not been characterized. Focd did claim, however,
that their experience with LDT truck catalyst technology will
be applicable to the 8,500-14,000 lb vehicle classes.
General Motors
General Motors argued that EPA's split-class approach was
flawed. Specifically, EPA's approach does not make compliance
any different for lighter HDTs because they would still be
certified on the HDE test. GM argued that the test procedure
itself will determine which technology is applied for emission
control. in fact, much more than minor modifications to LDT
systems would be required for usage on the heavy-duty test. GM
argued that catalyst-equipped HDGEs will exhibit unacceptable
durability and performance if certified on the transient engine
test procedure. GM claimed that they were unable, based upon
the lack of data, to define regulatory requirements based upon
the engine dynamometer test procedure.
General Motors also took issue with EPA's rationale for
splitting the classes. GM disagreed with EPA's conclusion that
LDTs and lighter HDTs were not significantly different;. GM
argued that EPA has not proved that they are sufficiently
similar to permit "easy" transfer of LDT control technology.
-25-
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General Motors did agree that the heavier the total
vehicle weight, the higher the catalyst temperatures were
likely.to be over the road. GM did not address the feasibility
of catalyst protection systems.
Manufacturers of Emission Controls Association
The Manufacturers of Emission Controls Association (MECA)
stated that EPA's split-class approach better balanced the
needs and costs of controlling emissions from HDGTs. MECA
further stated that if the operating environments of Classes
IIB and III trucks are "...not significantly different both in
'terms of emission levels and thermal exposure from that
experienced with vehicles currently equipped with catalysts,
then it is expected that conventional light-duty truck catalyst
technology could be applied with relatively minor modifications
to trucks in those classes."
MECA also stated that several of its member companies are
already working to develop catalysts for the Classes IIB and
III trucks, and also to develop catalyst components that will
withstand higher temperatures.
With respect to leadtimes, if LDT catalyst technology is
readily transferable, MECA claims that adequate quantities of
catalysts "...could be produced well within the timeframe
needed to supply 1987 model year trucks." "If more heat
resistant systems are needed for certain Class IIB and III
vehicles, some additional development time will be necessary."
Natural Resources Defense Council
The Natural Resources Defense Council (NRDC) took strong
exception to EPA's performance on the regulation of HC and CO
emissions from HDTs. NRDC stated that EPA's split-class
approach should mandate the entire 90 percent reduction in HC
and CO emissions for the lighter class by 1985, instead of
1987-88 as EPA's staff paper suggested. NRDC supported the
provision of a 1-year "safety valve" exemption for vehicles
subjected to more severe operating conditions, _if a need for
such could be publicly demonstrated. NRDC also recommended
that EPA seriously consider extending the lighter class upper
weight limit from 14,000 to 20,000 lbs. GVW to prevent vehicle
migration to higher weight classes.
NRDC also argued that the heavier classes should not be
given a permanent exemption from the 90 percent reduction
standards, even if such an exemption were technically justified
for 1985 or 1986. NRDC claimed that a permanent exemption is
not only detrimental to air quality, but also beyond EPA's
legal authority.
-26-
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Analysis of Comments
There are four basic questions concerning the issue of
catalyst feasibility for HDEs: 1) can the catalyst-based
standards be met at low mileage, 2) what type of catalyst
system and hardware are needed to allow compliance, 3) what
type of overtemperature protection is necessary for a catalyst
operating at HDE conditions, and 4) how much leadtime is
required for the development and production of such systems?
These questions will be addressed in the following analysis,
along with public comments to EPA's March 16, 1983 staff paper
wherein EPA originally proposed the "split-class" approach.
Low-Mileage Feasibility of Catalyst-Based Standards
EPA's decision to defer catalyst-based standards beyond
1984 was not a technical one, but based primarily upon economic
grounds and leadtime concerns. EPA concluded on January 21,
1980[1] that catalysts are feasible for use on HDGEs, and this
analysis will not reiterate the detailed findings of that
rulemaking. The associated Summary and Analysis of Comments
document, published in December 1979,[93, discussed a limited
test program which had been conducted by EPA during which the
statutory standards had been achieved at low mileage on two
test engines using catalysts. The conclusion of feasibility
was, therefore, supported by actual testing conducted by EPA.
Since that time, EPA has collected data from three
additional catalyst-equipped heavy-duty gasoline engines. (All
five catalyst-equipped heavy-duty gasoline engines and their
weighted cold/hot start transient test emissions are listed in
Table 1-8.) In this more recent testing, EPA retrofited an IHC
404 CID engine with two three-way catalysts and two oxidation
catalysts. A Ford 1985 prototype 7.5L HDE equipped with
oxidation catalysts was also tested at the EPA facility.
Finally, a GM 350-CID engine, with both a three-way and an
oxidation catalyst, was tested at Southwest Research
Institute. In addition, EPA notes that GM has tested a 1985
prototype 350-CID engine equipped with oxidation catalysts, and
submitted that data to the Agency as part of the cooperative
effort to determine the correlation between EPA and MVMA test
cycles. All engines yielded emissions well below the 15.5
g/BHP-hr CO and 1.3 g/BHP-hr HC standards (see Table 1-8).
Thus, laboratory testing of heavy-duty gasoline engines
equipped with catalyst systems has established that these
engines can comply with the statutory standards at low mileage.
Likely Emission Control Stategies
EPA believes that LDTs and most lighter HDTs are not
subjected to significantly different operational environments,
-27-
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and that existing LDT catalyst technologies and strategies can
be modified for use by HDEs (see below) . The only significant
difference affecting compliance technology between LDTs and the
HDEs for which catalyst standards will apply is, as properly
noted by GM, the larger engine exhaust mass flow induced by the
heavy-duty transient engine test. This difference should only
be manifest in the CO emissions. Necessary modifications to
LDT control technology to permit compliance with the CO
standard on the heavy-duty test include both changes to the air
injection system and to the catalyst system itself.
Adding air to the catalyst ensures that there is
sufficient oxygen to allow the oxidation of CO emissions. Air
injection is most important, and potentially problematic, at
full-power modes when the engine is operating under relatively
richer mixtures. Most of the CO emissions generated on the
transient test arise during these modes, and therefore
high-power CO emission control is critical. Given the already
high exhaust temperature at full power, substantial oxidation
of the relatively abundant concentrations of CO could
potentially raise catalyst temperatures to unacceptable
levels. It has been argued by manufacturers that this fact may
be the most difficult development problem to solve: any
emission control system with sufficient air injection to permit
CO compliance on the heavy-duty test, if that calibration is
carried through to the in-use vehicle operating for sustained
periods at full power, will create catalyst overtemperature
problems in-use. In turn, catalyst durability could be
severely impaired..
EPA's testing of the Ford 7.5L (see Table 1-8) examined
the relationship between CO emissions and the injection of air
to the catalyst. (Evaluations of catalyst temperatures were
also made, and are discussed below with respect to catalyst
protection systems.) Solenoid valves were installed in the
engine's air injection system so that complete control of when
air was being injected into the catalyst was achieved. Testing
was conducted such that different amounts of air were added to
the catalyst at wide open throttle (WOT) . (WOT was defined as
the condition when the manifold vacuum was equal to or less
than 2 inches Hg, the point at which power enrichment was
observed to substantially begin.) Figure 1-3 shows the
observed trade-off between hot start CO emissions and the
diverted air; Table 1-9 lists the hot start emission data.
Even though WOT represents only a small amount of the total
test time (4.5 percent), the CO emissions attributable to this
fraction of operation are relatively high. By allowing more
air to reach the catalyst, (i.e., air was injected a greater
percentage of the time the engine was at WOT) , there was a
dramatic reduction in CO emissions. In fact, with full-time
air injection, CO emissions were virtually eliminated.. EPA's
-2 8-
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Table 1-8
Catalyst Feasibility Testing
on the EPA Transient Test Cycle
Engine
1979 GM 292
1978 Production
IHC 404
Test
Facility
EPA
EPA
EPA
Weighted Emissions
(q/BHP-hr)*
HC
.58
.28
.32
CO
12.25
8.98
3.74
Comments
Dual 50 g/ft3 catalysts,
2:1 ratio of platinum
palladium
Dual air pumps, 4-113 in3
oxidation catalysts.
Extrapolated emissions
with fourfold increase in
air injection, four
oxidation catalysts.
EPA .68
1975 GM 350 SwRI .39
1985 Prototype EPA .72
Ford 7.5L
Prototype GM 350 GM .53
3.6 Dual-bed system and EGR,
closed loop feedback
carburetor, 2-151 in3
TWC and 2-173 in3
oxidation catalysts.
5.6 COC/TWC pelletized
catalysts, closed-loop
feedback carburetor.
7.22 4-150 in3 COC LDT
catalysts in parallel,
dual air pumps.
5.62 2-260 in3 COC new
pelletized catalysts.
EPA cycle based.
-29-
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Table 1-9
Hot Start CO Emissions As A Function Of
Air Diversion at WOT
CO Hot Start
Air Dumping Emissions
% Time at WOT % Time of Complete Transient Test (g/BHP-hr)
0 0 .79
30.4 1.4 3.40
47.4 2.2 5.88
100.0 4.5 11.40
Note: Maximum catalyst bed temperature did not vary
significantly between any of these tests, and never exceeded
1,600°F.
-30-
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Figure 1-3
Hot-Start CO Emissions As a Function of Diverted Air From the Catalyst
I2.0r
10.0-
i
(jJ
B . 0
Hot-Start
BSCO
g/BHP-hr
E . 0
H . 0
2 . 0
0 . 0
0
20 H0 E0 00
% of Time Air is Diverted at WOT
00
-------
testing also indicated that as much as 60 percent of the air
can be diverted from the catalyst at WOT while still attaining
a target CO emission level of 7.1 g/BHP-hr (EPA cycle based).*
This ability to "by-pass" air, while still attaining required
emission levels, has important implications for catalyst
protection systems, as discussed later in this analysis. In
summary, however, EPA sees no obstacle which would prevent
modification of existing LDT or HDE air pump systems for usage
with HD cf-atalysts.
With respect to catalyst design, the two most important
factors with respect to catalyst application to HDGEs are the
noble metal loading and catalyst size. Location and geometry
of the, catalyst also affect its efficiency, as does substrate
and noble metal material and density. Due to the higher mass
flow of exhaust observed at full power on the HD test cycle,
some changes may need to be made to existing LDT catalyst
systems to maintain adequate CO oxidation efficiencies at these
modes. In the worst case, larger, more heavily loaded
catalysts may be needed. In other cases, changes to the
exhaust and catalyst system geometry to increase gas residence
time and eliminate "break through" at maximum exhaust flow will
be necessary.
To evaluate how changing the geometry of the catalyst
system affects its efficiency, EPA recently tested a Ford 7.5L
engine with two catalyst configurations: 1) four catalysts in
parallel, and 2) two sets of two catalysts in series. The
brake specific carbon monoxide emissions for the parallel
version were 59 percent lower than the emissions for the series
version. By splitting the exhaust four ways instead of two,
the exhaust flow velocity decreased, thereby increasing the
residence time of the gas in the catalyst. This presumably
allowed more time for the oxidation reaction to occur
(eliminating "breakthrough"), and thus yielded lower overall CO
emissions.
In summary, industry has several design options to
maintain the required catalyst efficiency at full-power modes
and to ensure that catalyst-equipped HDGEs meet the required CO
target level. (EPA's earlier analysis[5] concluded that HC
emissions will be reduced as a matter of course, and will be
achieved primarily by assuring sufficiently prompt catalyst
light-off on the cold start; EPA's recent data substantiated
these earlier conclusions.) EPA believes that these
Target CO Emission Level = 1/DF X 1/AQL X Emission
Standard, where AQL = 1.283 (from above), and the
multiplicative DP = 1.7 (from Reference 9).
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modifications to air injection and catalyst systems are
possible. Moreover, EPA believes that they represent the
transfer of known emission control technology to different
applications, and do not represent fundamental technological
unknowns.
Catalyst Survivability
High operating temperatures create problems for
maintaining catalyst efficiency over time:
"The primary material used currently to support the noble
metal catalyst in automotive converters is gamma alumina,
in the form of either pellets or a washcoat on cordierite
monoliths. At elevated temperatures, a phase change to
alpha alumina begins which is accompanied by a reduction
in the structural strength and surface area of the
material. Active catalyst sites tend to diffuse and
agglomerate as well as become inaccessible due to the loss
of porosity; this process effectively reduces the number
of sites available for catalysis and hence lowers the
efficiency of conversion. Finally, the magnitude of the
physical changes which occur in the alumina above the safe
operating temperatures is a function of temperature, time
of exposure, and the presence of certain ions which
stabilize the gamma lattice."[9]
Due to the time and condition dependency of catalysts,
there is ho exact temperature above which a catalyst will
suddenly fail. It is generally accepted that above 1,800°F, a
catalyst will suffer serious damage. Operation between 1,600°F
and 1,800°F is possible, but thermal degradation increases with
time spent within that temperature range.
While none of the manufacturers in their comments disputed
that the emissions from a heavy-duty engine can be reduced
below the standards, they argued that catalysts are not
feasible for all trucks. They argued that heavier trucks cause
special problems for catalysts, such as the continually higher
temperatures and greater mass flow of emissions from vehicles
which spend a large percentage of operational time at full or
very high power. They contended that these conditions
seriously threaten the durability of currently available
catalysts. EPA has since recognized the manufacturers'
concerns of increased difficulty and cost of protecting
catalysts under these circumstances, and thus EPA proposed the
split-class approach as a solution.[7] In essence, the
split-class approach allows more time for application of
catalyst technology to worst case operational applications.
The heaviest HDGVs (above 14,000 lbs. GVW), and also a limited
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number of lighter vehicles intended for the most severe
applications, would continue for now to meet non-catalyst
standards of 2.5/40.0. For these reasons, EPA believes that
catalysts would not see extended service in severe operating
temperatures if the "split-class" approach were adopted. This
"split-class" approach is therefore the most important factor
in assuring catalyst durability, presuming the use of existing
catalyst materials and substrates.
Recent testing at EPA also included examination of the
catalyst temperatures under various types of operation. The
catalyst bed temperature of the Ford 7.5L heavy-duty engine
never rose above 1,600°F during the transient test cycle for
the parallel catalyst version; the version with series catalyst
had maximum bed temperatures approximately 50°F higher in the
catalysts closest to the exhaust manifold. A Ford 302 LDT
engine that was tested on the hde transient cycle by EPA had a
maximum catalyst temperature of 1,640°F. Catalyst temperatures
were also observed under conditions more severe than the
transient test. Table 1-10 lists the maximum catalyst
temperatures during WOT engine maps for two engines tested by
EPA. Mapping conditions are extreme, and as expected, the
catalyst temperatures are higher. Indeed, catalyst
temperatures typically reach a maximum after the engine
operates for sustained periods of time at WOT. Protection of
the catalyst from too much oxidation of CO would be necessary
at these conditions, if such conditions were expected to
routinely occur in-use. (Note that these conditions are not
seen on the transient test.) Again, however, EPA believes that
the "split-class" approach would virtually eliminate sustained
full-load operation from the vehicles required to use catalysts.
Aside from the elimination of the applications most
detrimental to catalyst survivability, there are other
strategies available to protect catalysts on HDGEs.
With increased air injection, the catalyst bed temperature
increases as more oxidation occurs. One obvious means of
protecting the catalyst at WOT is to divert the injected air
from the catalyst mechanically, thus precluding increased
oxidation. However, air injection cutoff at full load also may
cut off CO control at the most significant moment. This
creates an inherent trade-off between catalyst temperature and
CO emissions.
This trade-off, however, is not significant enough to
preclude compliance with the statutory CO standards. EPA bases
this judgment on the test data discussed above, with which it
was demonstrated that, for at least one engine, air injection
could be completely diverted for up to 60 percent of the time
spent at WOT on the transient test, and sufficiently low CO
emission levels could still be maintained (see Figure 1-3 and
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Table 1-10
Maximum Catalyst Temperature During WOT Engine Map
Engine
1980 GM 305-CID LDVE
equipped with air/
oxidation catalyst/
EGR
»
II
1985 Ford 7.5L HDE,
equipped with air/
oxidation catalyst
Catalyst Configuration Temperature, °F
One catalyst, stock 1,734
location
4.5 feet downstream 1,660
6.5 feet downstream 1,402
behind muffler
4 catalysts in parallel 1,650
6 feet downstream
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Table 1-9) . This indicates to EPA that some form of the WOT
air injection cutoff presently found on LDTs could be applied
to HDGEs. In short, additional catalyst protection can be
provided while still maintaining acceptable emissions levels.
Over-temperature protection systems, particularly for
non-catalyst engines, have been discussed at some lenth by GM
in earlier submissions. GM discussed several concepts,
including one which would completely cut off full-power air
injection after a certain amount of time (e.g., one minute) at
sustained full power. GM noted that maximum temperatures
require a certain amount of time to build up, and that such a
system would protect the engine, and at the same time would be
required very little in typical urban driving. GM's apparent
concern, however, is that EPA may rule such a system to be a
"defeat device" and forbid its use. EPA at this time cannot
specifically approve or disapprove any system described to the
Agency in a cursory or qualitative fashion; indeed, EPA's
"split-class" approach should eliminate the need for such a
system for now. However, past EPA policy with respect to the
determination of defeat devices does not necessarily preclude
the use of such a system. In general, EPA policy has been not
to classify a technology as a defeat device if it can be
demonstrated that such a device is essential for protecting the
integrity of the engine, the integrity of the emission control
system (e.g., catalysts), or the safety of the vehicle. In
short, provided that such demonstrations can be made (for
either catalyst or non-catalyst engines), additional
flexibility could be available for protection from excessive
temperatures, despite EPA's present belief that such protection
is not currently necessary.
An additional means of providing temperature protection
for the catalyst system has been discussed in earlier EPA
analyses[9]--the ability to relocate that catalysts further
downstream in the exhaust system. There are limitations to the
degree of relocation protection available, primarily because HC
emissions tend to increase dramatically as catalyst light-off
time is sufficiently increased. However, a limited amount of
temperature protection should certainly be available through
relocation of the catalyst.
Finally, one additional measure providing major
flexibility for certification will be available to the
industry; EPA intends to retain the option of allowing a
manufacturer to certify any vehicle of 10,000 lbs. GVW or less
on the LDT chassis test procedure to LDT emission standards.
Whether or not this option is exercised will be based upon the
manufacturer's judgment of relative compliance costs; it is an
option, however, which remains available.
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in summary, EPA does not expect HDGE catalyst durability
to represent a major problem. The "split-class" approach
eliminates the most problematic applications. Several other
techniques of catalyst and engine temperature protection are
available. Air injection diversion at full load would be a
technical derivative of systems already in production for LDVs
and LDTs, and can be calibrated in such a way to both provide
protection and achieve required emission levels. Catalyst
relocation can also provide additional minor protection. Other
protection systems could be used, if EPA were convinced that
they were truly necessary for engine or catalyst survival.
Leadtime
This discussion focuses on the technical leadtime
necessary to allow compliance with the "split-class" approach;
legal issues regarding leadtime are specifically addressed in
the Preamble of this rulemaking.
An outline of the technical ability of the manufacturers
to comply with the statutory standards for HDGEs in Classes iib
and III applications is presented below. This general schedule
(Figure 1-4) assumes a significant, although certainly
attainable, compliance effort by the manufacturers, of course,
the specifics of the situation facing each manufacturer will
determine exactly how much time is necessary for each phase of
the effort and what sequence will be followed. The schedule in
Figure 1-4 and the discussion below are intended to illustrate
what needs to be known and what needs to be done; by allowing a
reasonable amount of time for each phase, the feasibility of
compliance is demonstrated.
The work can be viewed as phases of development,
dynamometer and vehicle assurance testing, dynamometer-based DF
determination, and certification. These phases are not
necessarily sequential; in fact, there is certain to be a
considerable amount of overlap. Assumptions that have been
made in developing this schedule are noted where appropriate.
There are a few decisions that will be made, at least on a
tentative basis, early in the development process. under the
split-class approach, where all worst case HDGEs (in terms of
difficulty of catalyst application) are certified to
non-catalyst standards, manufacturers are expected to divide
their HDGEs into families on the bases of displacement and
catalyst use. The families will be divided in such a way as to
minimize disruption to the manufacturer's product line and
inconvenience to the consumer. in addition, manufacturers will
avoid situations that could result in competitive disparities;
for example, a manufacturer would not want to use
catalyst-equipped engines in vehicles that are in direct
competition with similar vehicles without catalysts from
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Figure 1-4
General Leadtime Schedule - MY87 HDGE Standards
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Production
Certifica :ion
Final design modifications (if necessarj
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iynamometer-based
sspgSTiipnrs
-------
a different manufacturer. In short, the manufacturers will
substantially determine the structure of their 1987 product
lines. The manufacturers will also make tentative judgments of
likely DFs and the impact of the SEA requirement (effective in
the 1986 model year) , and thereby estimate target emission
levels and the likely hardware and engine calibrations needed
to begin development.
The most important phase, which EPA expects to last until
October 1984, is for development work. It is clear from the
history of this action and from manufacturer comments that
preliminary development work has already been underway for some
time, that a significant portion of the necessary work (i.e.,
reduction of engine-out emission levels) will have been
performed in complying with the 1985 model year interim
standards, and that early catalyst testing has been in progress
since January 21, 1980. (For example, in comments submitted to
EPA in April of 1982, GM provided a lengthy submission covering
their heavy-duty catalyst development work to date.) EPA
believes that the most significant problem to be solved during
development is determining the catalyst configurations and
engine calibrations that will be needed in order to demonstrate
compliance on the HDGE transient test. Technically, this is a
relatively straightforward engineering problem of applying
known technology to new applications. As noted earlier in this
chapter, the same generic technology will be used, with
problems and engineering parameters similar to those
encountered in applying catalysts to LDTs.
It is assumed that accelerated dynamometer testing, a
fundamental part of engine and catalyst development, will occur
during the development phase. Limited dynamometer-based DF
assessments can also be conducted as part of the development
phase in order to provide preliminary DFs. Following this,
worst case durability assessments will be run to check for
catastrophic failures. Such failures will become apparent in
accelerated dynamometer testing, the last round of which is
estimated by EPA to extend three months beyond actual
development. (For mileage/service accumulation purposes, this
testing may proceed 24 hours a day under automatic control.
Thus the 1,500-hour half-life equivalent could be reached in as
little as 2.4 months, assuming operation for six days per
week. Note that GM's standard corporate durability test
generally runs about 200 hours.) Approximate DF determinations
based on dynamometer operation for the equivalent of the
full-life (3,300 hours) could therefore be completed
conservatively within eight months after the development phase
is concluded.
After the worst case durability assessments are completed,
EPA estimates that basic vehicle assurance testing could be
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done in about four months. This vehicle assurance testing will
allow comparison of in-vehicle and dynamometer-based DFs, as
well as assessment of the effectiveness of vehicle
modifications (heat shields, catalyst location and mounting),
system reaction to on-road phenomena (vibration), and overall
effect on performance characteristics (driveability). Four
months is adequate time to accumulate at least 25,000 miles of
in-vehicle use, assuming 10 hours per day on the road for 5
days per week at an average speed of 30 mph. Vehicles in this
program could be left in service; only the catalysts need to be
switched periodically for inspection and oxidation efficiency
testing on well-characterized engines. Assuming that the
in-vehicle testing conditions are appropriately planned, four
months should be more than enough time for identification of
any vehicle-related flaws.
EPA assumed three months beyond the work described above
for final design modifications to be implemented, if any are
found to be necessary. All of this could be completed by
September 1985, at which time production tooling commitments
could be made. At this point a full year would remain before
model year 1987 "Job 1" production must begin.
Although EPA considers the possibility to be remote, any
fundamental problems that may arise should be evident after the
completion of vehicle assurance testing and dynamometer-based
preliminary DF assessments. Existing regulatory provisions
would allow a manufacturer to petition EPA for relief in the
event a serious risk of non-compliance appeared likely at this
time. EPA does not believe, however, that such relief will be
necessary on the basis of all information available at this
writing.
The remaining 12 months before "Job 1" would be used for
final dynamometer-based full-life DF determinations, which
should take eight months or less, and certification. Under
procedures applicable for 1985 and later model years,
durability testing is not required to be a part of the formal
certification process. If further changes to calibrations or
hardware appear necessary, manufacturers would have the option
of foregoing the eight month durability assessment, and merely
use engineering judgment or use predetermined DFs for
certification. Certification should then begin no later than
May 1, 1986, and should take no longer than four months.
In summary, EPA estimates that compliance with the
"split-class" approch is feasible for the 1987 model year.
Having outlined a general schedule that demonstrates the
feasibility of compliance by model year 1987, EPA takes issue
with the technical leadtime estimates supplied by Ford in its
-40-
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comments. Ford considerably overstated the amount of time
necessary, and seemingly disregarded the considerable progress
that has already been made. Where Ford has included three
complete iterations of designing, building, and testing, EPA
believes that at most two iterations will be required,
particularly because of existing experience with ldt technology
and because all worst case applications are excluded under the
split-class approach. Ford also estimated the certification
process to last for three years, which EPA finds unreasonable
and unlikely.
on the other hand, the EPA leadtime estimates allow for
little slack time. Despite EPA's judgment that legal authority
exists for requiring compliance by model year 1986, the
elimination of 12 months from the time estimates discussed
above would preclude orderly development and make the risk of
non-compliance for 1986 unacceptably high. with respect to
1987, EPA again stresses that all truly worst case HDGE
applications, in terms of catalyst use, are excluded from the
statutory standards by the split-class approach. in addition,
catalyst-forcing emission standards for HDGEs were first
promulgated in 1979. The interim standards for 1985-86 were
never intended to defer catalyst standards permanently, but
merely to provide short-term economic relief. Thus the. Agency
is confident that implementation of this approach by 1987 poses
no insurmountable difficulties for the industry.
Conclusions
Statutory emission standards (1.1 g/BHP-hr HC and 14.4
g/BHP-hr CO based upon the MVMA cycle) for Classes IIB and III
HDGEs should be promulgated for the 1987 model year. All
heavier HDGEs should continue to meet non-catalyst standards,
as would the small number (5 percent of total Classes IIB and
III sales; see the "migration" issue, Section B.12, for further
information) of lighter vehicles allowed to certify to
non-catalyst standards on the basis of application.
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References
1. "Gaseous Emission Regulations for 1984 and Later
Model Year Heavy-Duty Engines," Federal Register 4136, Vol. 45,
No. 14, Monday, January 21, 1983.
2. "Control of Air Pollution from New Motor Vehicles
and New Motor Vehicle Engines; Revised Gaseous Emission
Regulations for 1984 and Later Model Year Light-Duty Trucks and
Heavy-Duty Engines," Federal Register 1642, Vol. 47, No. 8,
Wednesday, January 13, 1982.
3. "Revised Gaseous Emission Regulations for 1984 and
Later Model Year Heavy-Duty Engines and Light-Duty Trucks,
Draft Regulatory Analysis," U.S. EPA, OANR, OMSAPC, ECTD, SDSB,
Chapter II, September 1981.
4. Derived from comments submitted to EPA Public Docket
No. A-81-20.
5. Derived from comments submitted to EPA Public Docket
No. A-81-11.
6. Letter from Charles L. Gray, Jr. to Ford Motor Co.,
General Motors, Chrysler, and International Harvester, June 17,
1982, EPA Public Docket No. A-81-11.
7. "Issue Analysis - Final Heavy-Duty Engine HC and CO
Standards," EPA Staff Report, March 1983, EPA Public Docket No.
A-81-11.
8. Letter to commenters from Charles L. Gray, Jr., plus
attachment, EPA Public Docket No. A-81-11, April 12, 1983.
9. Summary and Analysis of Comments to the NPRM,
"Gaseous Emission Regulations for 1984 and Later Model Year
Heavy-Duty Engines and Light-Duty Trucks," EPA, OANR, OMS,
ECTD, SDSB, December 1979.
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2. Issue: Useful Life
Summary of the Issue
This issue addresses the useful-life provisions that will
apply to 1985 and later model year light-duty trucks (LDTs) and
heavy-duty engines (HDEs). On January 12, 1983, EPA proposed a
revised full-life useful-life approach and an alternative for
comment (48 FR 1472). This section of the Summary and Analysis
of Comments deals with the responses to the proposal and the
selection of the appropriate useful-life approach in response
to those comments.
Summary of the Comments
Introduction and Synopsis of Events
Useful life is the period, expressed in terms of time or
vehicle miles, over which in-use vehicles/engines are required
to demonstrate compliance with the applicable emission
standards and the period for which they are required to warrant
the emissions performance of their products. In 1979 and 1980
EPA promulgated regulations effective for 1984 and later model
years that contained revised useful-life periods for LDTs and
HDEs. Useful-life periods were changed from fixed intervals,
representing periods representing somewhat less than half the
service life of these vehicles/engines, to
manufacturer-determined periods representing the full average
period to engine retirement or rebuild.
EPA adopted these reguations over concern about the in-use
performance of HDEs. Half-life regulations provided no
incentive for manufacturers to be concerned about the long term
emissions durability of their engines, since they had no
liability for their performance past the half-life
certification period. This problem could be only partly dealt
with by establishment of lower emission standards. Lower
standards would lower overall average emissions, but would not
control departures from standards during the second half of a
vehicle's life due to what are often know as "gross emitters".
Gross emitters are those vehicles whose emissions are increased
severalfold above normal due to the failure of emission control
hardware. The in-use failure of emission control components
could completely eliminate the improvements gained by lower
standards. Indeed, indications are that as more advanced
technology comes into use for control of emissions, the effects
of in use failure becomes much more pronounced.
The goal, then, was to focus manufacturer efforts more
toward in-use performance and durability of their engines and
to insure that emission control systems were fully capable of
lasting as long as the average engine. Full-life useful life
provided that incentive, and gave EPA enforcement authority to
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deal with problems in the second half of a vehicle's life. It
helped insure that durability would not be sacrificed in an
effort to minimize costs. EPAs analysis of both the costs and
air quality impacts of full-life useful life indicated that it
was a beneficial and cost effective program.
Subsequent to that rulemaking, LDT and HDE manufacturers
raised a number of issues relating to the practical problems of
useful-life determinations and possible high costs of
implementing a full-life useful-life approach. As a result, in
April of 1981 EPA agreed to undertake a further study of the
useful-life issue as a part of the President's program to
provide regulatory relief to the automotive industry.
Comments received during the several comment periods and
public hearings held during the course of this study led to the
January 13 proposal. EPA offered two useful-life options in
the NPRM: 1) a modified full-life requirement designed to
address previously expressed concerns regarding full-life
implementation, and 2) an extended half-life proposal with
slightly more stringent emission standards to compensate as
well as possible for the reduced stringency of half life. A
formal durability testing program accompanied the half-life
proposal, whereas the full-life allowed manufacturers to design
their own programs. EPA's stated preference was for the
modified full-life option; the half-life plan was provided only
in the event of unforeseen problems with resolving full-life
implementation issues.
The majority of the manufacturers favored a half-life
useful-life definition; however, none found the EPA half-life
proposal with the adjusted standards and extended durability
testing to be acceptable. Although some manufacturers were
willing to accept a longer useful-life period than presently
exists none was willing to also accept the downward adjustment
in the emission standards. Rather, they advocated a half-life
useful life with no adjustment of the standards or durability
testing requirement. However, acceptability of the half-life
plan to EPA was fully contingent upon the adjusted standards to
account for the decrease in the compliance period and upon
extended durability testing requirements to increase the focus
on emission control performance at higher mileages. The Agency
felt that without those compensating qualifications, all of the
environmental benefits of full life would be lost and such a
change would effectively reduce the stringency of the
standards. Since no commenters supported the provisions of the
extended half-life approach as proposed by EPA, and since three
commenters expressed a preference for modified full life, it is
EPA's intention to retain the modified full-life approach.
Therefore, the half-life plan will not. be analyzed further, and
the remainder of the analysis will concern itself only with
comments pertinent to modified full life.
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Before turning to analysis of specific comments it is
important to reaffirm EPAs belief in the value of full-life
useful life. EPA continues to hold to its original
justification for this program as outlined above. Commenters
have argued that EPA has not conclusively demonstrated that the
in-use need exists to an extent which justifies taking action.
While it is true that there is not a large body of data to
demonstrate the need, EPA believes that the logic of the
situation, along with what data is available argues strongly
for the establishment of full-life useful life. Indeed, the
very vigor of much of the opposition to extending
manufacturers' responsibilities into the second half of the
useful life argues in favor of the need for this action. If,
as argued by manufacturers, the current durability of emission
control components is adequate, then there is little risk
involved in extending the useful life period. EPA believes
that full-life useful life is needed to insure durable
components and to provide an enforcement mechanism for in-use
problems.
The comments have been divided into major and minor issues
for convenience of analysis. Within the group of major issues,
five significant areas have been identified. These include:
1) legal objections to EPA's modified full-life approach, 2)
concerns related to the recall provisions, 3) the heavy-duty
diesel engine subclasses, 4) the assigned useful-life periods,
and 5) the air quality benefits associated with full life. In
response to the last issue, an update of the environmental
impact and cost effectiveness of useful life was undertaken
which forms a part of the Regulatory Support Document.
Briefly, since it will not be considered further here, this
analysis shows that the adoption of EPA's modified full-life
approach will produce up to a 1 percent improvement in air
quality for ozone and CO in the mid-late 1990s. The analysis
further shows that full life is very cost effective in
comparison with other emission control strategies, projecting
costs-effectiveness values of $206-484 per ton for HC and
&12-24 per ton for CO. Interested parties are referred to
Chapter 3 of the Support Document for further analysis in this
area. Discussions of the other four main issues and several
minor issues are presented below.
Legal Issues
Summary of the Comments
A large number of comments were received concerning EPA's
legal authority for implementing the modified full-life
approach. Comments fell in four major areas: 1) statutory
authority for the full-life concept, 2) authority to establish
different useful-life periods for purposes of certification,
warranty and recall, 3) authority to group LDTs under 6,000
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lbs. GVW with heavier LDTs and HDEs foe the purposes of useful
life# and 4) the appropriate period of recall liability for
in-use vehicles and engines. These are discussed below.
Many comments were received that reiterated (either
directly or by reference) claims made during the original
rulemaking that EPA does not have the statutory authority to
implement a full-life useful-life definition. A substantial
number of commenters addressed the issue of Congressional
intent with respect to a half-life versus a full-life
definition, and cited portions of the legislative history of
the Clean Air Act which they believed demonstrated that
Congress intended that the half-life concept be retained for
LDTs and HDEs, regardless of the actual language in the Act.
Second, comments were received on the modified full-life
proposal which argued that the Act limits EPA to a single
useful-life period for both certification under Section 202(a),
and the in-use programs contained in Section 207 (warranty and
recall). The commenters therefore concluded that EPA was
precluded from establishing a useful-life period for warranty
that was different from the useful-life period for
certification and recall liability.
Third, Volkswagen of America (VW) stated that EPA had no
statutory authority to create a separate LDT class for
useful-life purposes for LDTs under 6,000 lbs. GVW. VW argued
that the court decision which initially led to the creation of
the LDT class by EPA (International Harvester vs. Ruckelshaus,
478 F. 2d 615, D.C. Circuit, 1973) applies only to the level of
the emission standards, and does not extend to other regulatory
requirements. Based on this premise, VW took the position that
LDTs of less than 6,000 lbs. GVW may not be required to conform
to a period longer than the statutory period for light-duty
vehicles (LDVs) (i.e. 5 years/50,000 miles).
Fourth, several commenters expressed concern about the
s,cope of their liability during a recall action. They believed
t,hat the full-life recall provisions would force them to "fix"
a;ll the vehicles/engines in the recalled group regardless of
their age, mileage, or condition. The comments took the
position that their recall liability should end with the
assigned useful life and that they should not be responsible
for any vehicle engine which has been rebuilt, regardless of
mileage.
Analysis of Comments
The question of Congressional intent and EPA's statutory
authority to adopt a full-life useful-life definition for LDTs
and HDEs was also raised when the full-life concept was first
proposed for these vehicle/engine classes. During those
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rulemakings, EPA prepared two separate Summary and Analysis of
Comments documents on the full-life useful-life proposals, one
each for LDTs and HDEs, and these are herein incorporated by
reference.[1,2] These analyses concluded, as EPA still
concludes, that the Clean Air Act as amended in 1977 provides
the Administrator full authority to set the LDT and HDE useful
life at any period of time and/or mileage longer than 5
years/50,000 miles if it was determined to be appropriate.
Manufacturers based their findings of Congressional intent
for half life on the differences between the Senate version of
the Clean Air Act Amendments of 1977 (S.252) and the final
version that emerged from the conference committee and was
later enacted. In the Senate version, the useful life for a
"motorcycle or any other motor vehicle or motor vehicle engine
would be a period of use the Administrator shall determine."[3]
In the Amendments as they were enacted, however, "motor vehicle
and motor vehicle engine" were removed from this clause and
placed in a new clause which read that useful life for "any
other" (than light duty) "motor vehicle or motor vehicle engine
(other than motorcycles or motorcycle engines)" was to be a
period of 5 years/50,000 miles "unless the Administrator
determines that a period of use of greater duration or mileage
is appropriate."[4] From this change in language, and the past
use of the half-life concept for LDVs, LDTs, and HDEs, the
commenters inferred that Congress intended EPA to retain the
half-life concept for LDTs and HDEs.
First, it should be noted that EPA's authority to
establish longer useful-life periods for LDTs and HDEs was
established in 1970. The 1977 amendments did not address LDTs
and HDEs directly, but were concerned with the problems of
existing law created with respect to motorcycles. Thus, the
1977 amendments are not directly relevant to EPA's authority to
set useful-life periods for LDTs and HDEs.
Moreover, in EPA's view, setting "any other motor vehicle
or motor vehicle engine" apart from motorcycles and light-duty
vehicles/engines simply retained a minimum 5 year/50,000 mile
useful life for LDTs and HDEs and did not alter the
Administrator's specific authority to set a period longer than
5 years/50,000 miles if it was determined to be appropriate.
Congress was aware of the ongoing litigation between Harley
Davidson and EPA on the issue of motorcycle useful life, and
specifically provided statutory language to permit EPA to
establish a useful life other than 5 years/50,000 miles for
motorcycles in Section 202 (d) (3). [5] Had this change not been
made, and the Senate version retained, the 5 year/50,000 mile
minimum would have been lost for LDTs and HDEs. Congress
desired to keep that minimum, which led to the creation of
Section 202(d)(2), which also contains EPA's authority to set a
useful-life period longer than half-life. Therefore,
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reducing vehicle emission," but are emission-related, have to
be warranted for only 2 years/24,000 miles under Subsection
207(a) (2) . [6] Nevertheless, Section 202 (a)(1) refers to "a
period of use" for light-duty vehicle useful life; Congress
evidently believed varying useful-life periods could exist
notwithstanding the apparent reference to a single period.
Since Congress was clearly aware of the possibilities involved
and yet did not specifically prohibit the Administrator from
making similar determinations for LDTs and HDEs, EPA concludes
that authority exists under the general and specific authority
mentioned above to allow the establishment of reduced warranty
periods, and that the Administrator is not restricted to only
one useful-life period for certification, warranty, and recall
purposes.
It should be kept in mind that the reduced useful-life
period for warranty is an attempt to be responsive to
manufacturers' valid concerns with having to warrant LDTs and
HDEs for their full useful lives, while not sacrificing the air
quality and durability benefits of the earlier full-life
useful-life requirement. EPA could have promulgated more
stringent half-life standards with increased durability
requirements, but opted instead for an approach that at least
was favored by some manufacturers.
Finally, although EPA believes, for the reasons set forth
above, that it would have authority to establish a different
useful-life period for purposes of recall, that is not what the
Agency has done. As discussed below, manufacturers in a recall
will be required to repair non-conforming LDTs and HDEs
regardless of age or mileage at the time of repair. EPA, as
part of this rulemaking, has simply established a policy that
LDTs and HDEs will not be tested for purposes of recall if they
exceed 75 percent of their useful life. Indeed, even in the
established LDV recall program EPA typically tests cars that
are only two to three years old, notwithstanding a 5-year
useful-life requirement. The recall policy established today
for LDTs and HDEs is an attempt to be responsive to
manufacturers' concerns that wornout or otherwise
unrepresentative engines may inadvertently be selected for
recall testing.
Turning to the issue raised by VW, EPA cannot accept VW's
contention that the decision of the Court of Appeals in
International Harvester v. Ruckelshaus was applicable only to
compliance with emission standards. The decision of the Court
led EPA to initiate a rulemaking which ultimately established
the definition of a new LDT class and an entire set of emission
regulations for new 1975 and later model year light-duty
trucks. (85 CFR - Subpart C) (See 38 FR 21362, August 7,
1973) . Since that time LDVs and LDTs have shared common
requirements only when it was found to be technologically
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appropriate (e.g., test cycle). Beginning in 1979 the LDT
class wa!s expanded from 0-6,000 lbs. GVW to 0-8,500 lbs. GVW,
and in. subsequent regulatory actions EPA has used the general
authority of Section 202(a)(1) to group the lighter weight LDTs
with the heavier LDTs for purposes of complying with mandates
of other portions of Section 202. In 1977, when Congress added
language to the Act authorizing EPA to establish classes and
categories for setting standards for HDEs, it specifically
ratified EPA's approach for LDT regulations.[7]
Given that the Court of Appeals ordered EPA to remove
light-duty trucks from the light-duty vehicle class in 1973,
and that EPA has operated with a distinct set of LDT emission
regulation and standards since 1975, EPA sees no merit in VW's
argument. EPA believes that setting LDT useful life under
Section 202(d) (2) is consistent with the past practice of
establishing separate LDT provisions, and is a correct usage of
Section 202(d)(2) since LDTs are neither LDVs nor motorcycles.
Finally, EPA recognizes the manufacturers' comments on
recall liability. Current EPA policy is that all
non-conforming vehicles/engines in a recalled family must be
"repaired" regardless of their mileage, age, or condition at
the time of repair. Recall evaluation testing will not be
conducted past 75 percent of the assigned useful life; however,
if a defect is discovered during such testing, it must be
remedied for all non-conforming vehicles/engines in that family.
The Agency is now involved in litigation over this
requirement (General Motors v. EPA, No. 80-1868, D.C. Circuit,
1980) , so it is subject to possible revision based on the
outcome. Final EPA response to these concerns is therefore not
possible at this time.
Conclusion
The Act contains the necessary authority to establish the
certification, recall, and warranty provisions embodied in the
modified full-life useful-life approach. EPA has significantly
revised these provisions in a way that should alleviate the
manufacturers' most pressing concerns, while preserving the
benefits of a full-life useful life-approach.
Recall Provisions
Summary of the Comments
A number of manufacturers have anticipated problems with
the three-quarter-life recall provisions proposed by EPA as
part of the modified full-life approach. The Engine
Manufacturers Association (EMA) and several industry commenters
stated that limiting recall evaluation testing to 75 percent of
the assigned useful life would not fully address the problem of
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including rebuilt and wornout engines in a sample selected for
recall testing. The commenters claimed that due to the
variability found in actual engine service lives, it was quite
possible that a substantial percentage of engines would be
rebuilt before reaching the 75 percent of assigned useful-life
cut-off point. For example, EMA estimated that 22-36 percent
of heavy-duty diesel engines would have been rebuilt and an
additional unspecified percentage would be in need of rebuild.
Commenters believed that the difficulties in screening such
engines would add to the cost of recall testing and might lead
EPA to "cut corners" by basing a recall on too small a sample
or by including marginal engines in the test program.
The commenters also expressed several other concerns
related to the recall program. Mack Trucks, Inc. expressed
concern over the potential impact of the 40 percent Acceptable
Quality level (AQL) of EPA's Selective Enforcement Audit
program on the recall evaluation program, stating that as a
result of the 40 percent AQL, there is a near 40 percent chance
that an engine taken randomly for recall evaluation may have
been above the standard when it left the production line.
Mack Trucks also stated that laboratory-to-laboratory
variability must be considered in any recall evaluations, since
results of the EPA/EMA round-robin test program indicated that
up to a 25 percent variation existed between certain test
facilities.
Mack also requested that EPA provide a three model year
"grace period" from recall liability for newly introduced
engine lines. Mack was concerned that even the best
engineering practices may not allow them to predict their
in-use emissions deterioration accurately for these new engine
lines, and that their in-use engines may exceed the emission
standards as a result.
Some manufacturers wanted EPA to limit recall liability to
a select list of emission control components only, although the
American Trucking Association (ATA) doubted that EPA had the
authority to do so.
Analysis of the Comments
The problem of screening vehicles/engines for improper
maintenance, abuse, rebuild, wearout, etc., prior to inclusion
in a recall sample is not new. Such screening is now
successfully conducted in the LDV and LDT recall programs, and
EPA expects to use a similar approach under full life for LDTs
and in the recall program currently being developed for HDEs.
The manufacturers are given several opportunities for
participation in the recall program. Under the current program
manufacturers are given the opportunity to comment or otherwise
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respond to the Maintenance/Use Criteria questionaire which
serves as the first level of screening for prospective
vehicles. The second level of screening is a physical
inspection of those prospective vehicles/engines which pass the
first level of screening. At this point, the manufacturers are
invited to be present at the inspection and to provide input to
EPA as to why a given vehicle may or may not be representative
for recall evaluation testing. Should any disagreement arise,
the current recall program allows manufacturers a full
opportunity to challenge vehicle selection. And, of course,
the manufacturers are. involved in the recall provisions as
discussed in Subpart S of 40 CFR Part 85. Finally, in the
unlikely event that disagreements with the recall sample
remain, manufacturers are given an opportunity, in an
adjudicatory hearing, to contest EPA's determination that the
class is in non-conformity. The results of that hearing are,
of course, judicially appealable.
The above procedures involving recall screening ensure
that the manufacturers are indeed involved in the current
recall screening process, and EPA fully expects that such
involvement will continue in the full-life LDT program and the
developing HDE recall program. EPA expects considerable
dialogue with the industry on the implementation details of
these new programs, and in fact some preliminary discussions
have been held. EPA presented a brief synopsis of the current
LDV/LDT recall program at the Useful-Life Workshop on February
18, 1983, and a subsequent meeting was held between EPA and EMA
representatives on June 2, 1983.[8]
In any event, EPA and the industry are in agreement on the
need to develop procedures and implementation approaches for
minimizing the possibility that a rebuilt or wornout engine
might be included in a recall evaluation sample. Since few
LDTs are rebuilt and no HDE recall program currently exists,
EPA believes that the full-life useful-life requirement can be
implemented now, and the details for implementing the
provisions of the recall program for LDTs and HDEs can be
refined in the future, through discussions between EPA and the
industry.
Although EPA can understand how Mack might make a
connection between the 40 percent AQL and its impact on the
recall program, there simply is none. SEA and recall are two
distinct EPA programs, addressing compliance on the assembly
line and in use, respectively. The AQL in SEA testing was not
established at 40 percent to condone nonconformance, but was
set at that level in recognition of manufacturing
practicalities and economic and other negative impacts of an
SEA failure (i.e., lost production, lost wages while a fix for
the problem is implemented, etc.). In fact, any vehicle/engine
which fails during an SEA must be fixed before it can be sold.
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It is still the Agency's desire and should also be the
manufacturers' goal, that every vehicle/engine produced meets
the emission standards when produced. Therefore, EPA does not
feel constrained by the 40 percent figure for the recall
program, since the goals of the two programs are different.
EPA also notes that the LDV SEA program includes a 40 percent
AQL and the LDV recall program has not suffered as a result.
In response to Mack's comments concerning
laboratory-to-laboratory variability and also as a partial
response to Mack's concern over the impact of the 40 percent
AQL, it should be noted that the lack of rigidly defined
procedures for recall evaluation and for determining that a
substantial number of vehicles/engines are in nonconformity,
provides EPA some flexibility for accounting for the impact of
such factors. EPA expects to continue judicious use of this
flexibility in the future to account for factors such as these.
EPA cannot agree to Mack's request for a 3-year grace
period from recall liability for new engine lines, while the
manufacurer gathers in-use data on the performance of its new
engines. Manufacturers do not introduce new engine lines to
the marketplace without extensive durability and assurance
testing both on engine dynamometers and in actual vehicles
before production begins. Given this practice, and EPA's
provisions which allow manufacturers to determine their
deterioration factors by any means they deem appropriate, the
manufacturers should be able to utilize the results of such
durability and assurance testing to determine a reasonably
accurate deterioration factor. To account for unforeseen
problems in use, the manufacturer can always build a cushion
into the certification deterioration factor or decrease
low-mileage targets and thereby minimize in-use noncompliance
risk. Manufacturers cannot be spared the liability of not
complying with the emission standards in use. This is a
central and important part of the mobile source control
program; it ensures that manufacturers build engine/vehicles
that perform well in use.
Regarding the idea of limiting recall liability to a
specific list of emission control components, EPA cannot accept
the manufacturers' position. The industry has argued that
emission-related components (i.e., those that affect emissions,
but are not specifically designed for emission control—fuel
injection systems, for example) should be excluded from recall
liability becuase they will be kept in good repair to avoid
degradation in performance and fuel economy. This may be true,
and, if so, defects uncovered in emission-related components
would be rare and should pose no problem to the manufacturers.
Conversely, recall evaluation testing may find that there are
significant problems with emission-related components, and a
recall program would assure correction of these problems.
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Publishing a list of select emission control components would
preclude the possibility of correcting such problems should
they be uncovered. Finally, in the recall provision of the
Act, Congress did not limit recalls to non-conformities caused
by certain components, but rather required remedial action when
a class of vehicles fails for any reason to conform to the
applicable emission standards.
Conclusions
EPA will work closely with the LDT and HDE manufacturers
to ensure that the new recall programs are implemented in an
equitable and reasonable manner, and that manufacturers'
concerns over wornout and rebuilt engines are properly
addressed. These implementation provisions will be developed
with public involvement, and will be modified in the future as
experience dictates. There is every reason to believe that
these new recall programs can work as smoothly as the current
LDV and LDT programs. EPA concludes that no additional recall
provisions are required at this time to implement the modified
full-life useful-life approach for 1985.
Heavy-Duty Diesel Engine Subclasses
Summary of the Comments
EMA and several manufacturers did not agree with EPA's
approach of subdividing the heavy-duty diesel engine (HDDE)
class on the basis of gross vehicle weight (GVW). In the
proposal, EPA subdivided the HDDE class into three distinct
subclasses based on a range of GVWs and then assigned
useful-life periods to each subclass. Under the EPA approach,
an engine's assigned useful-life period would then be derived
from the GVW of the vehicle in which the engine was installed!*
EMA commented that this approach was flawed because a given
engine line might be sold for use in applications which
encompassed more than one HDDE subclass. EMA also did not like
the nomenclature which EPA used to identify its three HDDE
subclasses (i.e., medium, light heavy, and heavy heavy).
As an alternative approach, EMA suggested splitting the
HDDE class into three subclasses based on the primary intended
service application for which the engine was designed and
sold. These three subclasses would be called light heavy-duty
diesel engines (LHDDEs), medium heavy-duty diesel engines
(MHDDEs), and heavy heavy-duty diesel engines (HHDDEs). The
LHDDE subclass would cover applications such as motor homes,
multi-stop vans, large utility vehicles, pickup trucks, and
delivery vans. The MHDDE subclass would cover engines that
were designed for short haul or intracity operation such as van
trucks, stake trucks, single axle tractor/trailers
combinations, and school buses. The HHDDE subclass would
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primarily entail engines designed for full-load, long haul
intercity operation, such as those used in over-the-road
tractor/trailer trucks and intercity commercial buses. EMA
further recommended that EPA review each manufacturer's primary
service category designation to ensure that engines were
properly classified for regulatory purposes.
Virtually all of the HDDE manufacturers concurred with
EMA's comments. However, Daimler-Benz and ATA suggested engine
horsepower as another plausible approach since it would also
allow the manufacturers to characterize the engines in the
manner in which they were normally used.
Analysis of Comments
The HDDE classification approach suggested by EMA has
considerable merit. Basing the HDDE subclasses on primary
intended service applications is preferable to the GVW-based
approach by EPA, because it avoids two potential problems of
the GVW-based approach. First, it avoids the potential design,
certification, and recall complications which arise if an
engine model would be used in more than one of the GVW-based
subclasses proposed by EPA. This problem is avoided simply
because GVW is removed as a useful-life determinant. Second,
it avoids the potential problems associated with atypical
applications within the GVW-based subclasses proposed by EPA.
For example, even though garbage trucks fall in GVW Classes VII
and VIII (HHDDE under the EPA GVW-based approach) their engine
requirements and vehicle usage patterns are not typical of most
Class VII and VIII vehicles. Under EPA's proposed approach
these engines would have been assigned the same useful-life
period as over-the-road trucks, which probably would not be
appropriate. The primary intended service application approach
avoids this GVW-based complication, and recognizes that a
typical MHDDE may be efficient in this application, and would
have a useful life typical of MHDDEs, not HHDDEs.
The HDDE classification approach suggested by EMA is
preferable to that proposed by EPA. For those engines which do
not readily fall into either the light, medium, or heavy
heavy-duty subclass, EPA is retaining the provisions which
allow the manufacturer to petition the Administrator for a
different useful-life period.
At this time, EPA foresees no need to review the
manufacturers' primary intended service determinations as
suggested by EMA, and does not desire to establish the need for
additional approvals during certification. EPA believes that a
labeling requirement could be used to assure that engines are
not misclassified. Under this approach, manufacturers will be
required to label HDDEs as to the subclass for which they are
certified. The label will also include alternative assigned
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useful-life periods, if applicable, as described above. Market
forces should then help ensure proper engine classification by
the manufacturer, and selection of the appropriate engine by
the purchaser. Although this approach should guard against
abuses, EPA retains the right to challenge any manufacturer's
practice in determination of subclasses should
misclassifications occur.
The horsepower-based approach proposed by two commenters
may also be plausible, because there is generally a
relationship between engine horsepower and other parameters
such as the load factor which could in turn adequately
delineate an engine's application. However, this approach is
not preferable to that proposed by EMA because no body of data
is readily available which could be used to develop an
appropriate relationship between engine horsepower and average
useful life.
Conclusions
The HDDE class will be split into three subclasses on the
basis of primary intended service application, as suggested by
EMA. Each engine will be labeled with the subclass for which
it is certified. The provision allowing a manufacturer to
request a different useful-life value under special conditions
will also be retained. However, these values will have to be
printed on the label.
Assigned Useful-Life Periods
Summary of the Comments
All of the manufacturers claimed that one or more of EPA's
proposed assigned useful-life periods (period to engine
retirement or rebuild) as too long. Since the comments
pertaining to the various assigned useful-life periods are
fairly specific and detailed, they will be grouped by
vehicle/engine class and each will be prefaced by EPA's
rationale for establishing the useful-life value which was
originally proposed. The development of the assigned
useful-life periods is more fully documented in an EPA
memorandum which was released concurrent with the proposal.[13]
a. Light-Duty Trucks
EPA's proposed assigned useful life of 12 years/130,000
miles was based on an average of the following data:
Engine rebuild surveys
Survey Data Research (SDR) 171,000 miles
"maximum likelihood"
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SDR "median ranks"
141,000 miles
Scrappage data
DOE 124,000 miles
Michigan Technological
University (MTU) 120,000 miles
Engineering Estimate
Myers, SAE 750128 100,000 miles
Average 131,200 miles
The two Survey Data Research (SDR) survey numbers were based on
the same set of survey data, aggregated and analyzed in two
different ways. Ford Motor Company stated that this was
inappropriate because if the data set forming the basis for the
two analyses were biased in any way, the effect of the error
would be doubled (since it would constitute 40 percent of the
average, rather than 20 percent). Ford believed that the data
were biased, because the two projected engine rebuild mileages
were higher than the mileage at which the average vehicle would
be scrappped by roughly 20,000 and 50,000 miles, respectively.
Ford claimed that this was contrary to the common sense
conclusion that the miles to rebuild should be less than the
mileage at the vehicle scrappage point.
EMA and GM stated that the use of scrappage data in
developing useful-life mileage values for LDTs and HDEs was
inappropriate because the data included engines that had been
rebuilt, therefore raising the average scrappage point
mileage. They also asserted that use of scrappage-rate data
represented a departure from the Agency's original regulatory
intent of basing useful life on mileage to engine rebuild. GM
carried this argument one step further, saying that useful-life
periods should be based on the need for rebuild rather than on
"owner action," (i.e., actually having the engine rebuilt). GM
did not offer any suggestions, however, as to exactly how this
determination was to be made, other than to say that they felt
EPA's previous effort to provide objective. end-of-life
indicators for screening wornout engines out of recall samples
(the rebuild criteria in 40 CFR §86.084-21) was "unworkable" in
terms of accomplishing the stated objective.
VW argued that the data used by EPA to develop the LDT
assigned useful life did not include the smaller 4-cylinder
pickups that have been introduced in the last few years and
which they felt are not designed for a useful life of 130,000
miles.
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b. Heavy-Duty Gasoline Engines
EPA averaged the following data in proposing an assigned
useful life of 120,000 miles for HDGEs:
Rebuild surverys
SDR "maximum likelihood" 134,000 miles
SDR "median ranks" 124,000 miles
Fleet Maintenance and
Specifying magazine[9] 100,000 miles
Scrappage rate data
DOE 129,000 miles
MTU 114,000 miles
Average 120,200 miles
Ford, GM, and EMA all felt that the useful life for HDGEs
should be 100,000 miles or less. This contention is based on
the arguments mentioned above for LDTs regarding scrappage data
versus rebuild data and also on their belief in the possibility
that the SDR survey data overstated mileage to rebuild. EMA
suggested the inclusion of data from a rebuild survey conducted
by the ATA and also engineering estimates from a draft study
done under EPA contract by Arthur D. Little, Inc.[10,11]
c. Heavy-Duty Diesel Engines
In the proposal, EPA split the HDDE class into three
subclasses based on GVW, and proposed useful-life periods based
on the general design and usage characteristics of each. The
"medium-duty diesel" subclass, all HDDEs in vehicles less than
19,500 lbs. GVW (Classes IIB-V), represented a relatively new
diesel application in a. field heretofore dominated by gasoline
engines and there were few data available regarding average
service life. However, EPA reasoned that since these engines
introduced as a replacement for HDGEs, they should last as long
as the gasoline engines they were designed to replace in order
to be competitive, and so a similar useful-life period of
120,000 miles was proposed.
The second subclass proposed, "light heavy diesel,"
(19,501-26,000 lbs. GVW - Class VI) had a useful-life period of
200,000 miles, which was determined by averaging the following
data:
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Rebuild Surveys
SDR (Class VI engines)
Fleet Maintenance and
203,000 miles
Specifying Magazine
229,000 miles*
Engineering Estimate
Myers
16 2,500 miles**
Average
198,167 miles
* Average of values for sleeved and non-sleeved bus engines.
** Midpoint of range.
The third subclass was called heavy heavy-duty diesel (GVW
above 26,000 lbs. - Classes VII-VIII). Since the data
available indicated that virtually all heavy heavy-duty diesel
engines were rebuilt, the proposed useful-life value was based
on an average of two rebuild surveys:
Since most manufacturers supported the EMA alternative
HDDE classification scheme discussed earlier, their comments
concerned both the methodology used by EPA to develop the
proposed useful-life values and EPA's methodology and its
results as they applied to the HDDE subclasses suggested by
EMA. Since EPA has accepted the EMA classification system, the
summary and analysis of comments for HDDEs will focus on those
comments pertaining to EPA's methodology for estimating
useful-life periods and the relationship between the assigned
useful-life periods proposed by EPA and the EMA HDDE subclasses.
For the sake of clarity, further references to the HDDE
subclasses will use the EMA terminology (LHDDE, MHDDE, and
HHDDE). When the subclasses proposed by EPA are mentioned,
their full names with be used (medium-duty diesel, light
heavy-duty diesel, heavy heavy-duty diesel).
Having presented the necessary preliminary information, we
turn now to the comments. First, no significant comments were
received on EPA's proposal that the medium-duty diesel assigned
useful-life period should be the same as that used for HDGEs.
Ford agreed with this approach.
SDR
267,000 miles
Fleet Maintenance and
Specifying Magazine
281,000 miles
Average
274,000 miles
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For the next subclass, EMA disagreed with EPA's use of the
vocational groupings in the Fleet survey as being
representative of LHDDE and MHDDE usage for establishing
useful-Life periods. The Fleet survey aggregated the data on
the basis of vocational application (e.g., bus fleet, utility)
as well as on the basis of some significant engine design
characteristics (sleeved versus non-sleeved engines). EMA
suggested that since most MHDDEs are non-sleeved, the MHDDE
assigned useful-life period should be based on the Fleet
rebuild mileage for non-sleeved engines (175,000) rather than
on vocational categories.
EMA and Ford suggested that the SDR survey rebuild mileage
for Class VI engines used in the EPA calculation of the
useful-life period proposed for light heavy-duty diesels was
inappropriate for use in calculating the useful-life for MHDDEs
under the EMA classification system. Even though the
light-heavy-duty subclass proposed by EPA and the MHDDE
subclass proposed by EMA are quite similar, it was thought that
the SDR sample for Class VI engines likely included a number of
premium HHDDEs which would raise the average rebuild mileage.
Thus, EMA and Ford believed that the MHDDE useful life should
be less than that determined for EPA's GVW-based light
heavy-duty diesel subclass.
It was also suggested that data from the ATA maintenance
survey and from the draft study by Arthur D. Little be added to
the data used for calculating the average useful-life periods.
Given this information, EMA, Ford and GM felt that the MHDDE
average full-life value should be 170,000 miles, based on the
change in methodology. Caterpillar felt the MHDDE figure
should be 150,000 miles, based on an average value of different
applications of their 3208 model.
There was not significant disagreement on the assigned
useful-life period of 275,000 miles EPA proposed for heavy
heavy-duty diesel engines, although several commenters noted
that operation of Class VII trucks is not typical of that of
Class VIII trucks. In their view, the 275,000 miles was far
more representative of Class VIII operation than Class VII
operation.
EMA also suggested that the EPA assigned useful-life year
values were not equivalent to the mileage values for the
various classes/subclasses. They argued that equivalency
should be maintained.
Analysis of the Comments
a. Light-Duty Trucks
EPA accepts the Ford comment regarding the use of two
different numbers resulting from alternative analyses of the
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same set of data in the SDR survey. EPA intended to use the
SDR data as a rebuild mileage survey, and to let the scrappage
rate data serve for high-mileage non-rebuilds. Since the SDR
"maximum likelihood" figure in question includes non-rebuilt
engines in determining average lifetime mileages, it would be
inappropriate to include it as a rebuild figure. Therefore,
EPA has dropped the SDR "maximum likelihood" value from the
averaging total and has used only the "median ranks" value,
which is limited to rebuilt engines.
Regarding the comments on including scrappage data in the
useful-life calculation, EPA believes the manufacturers have
misinterpreted the Agency's intent regarding what constitutes
useful life. In the original full-life useful-life
regulations, useful life was defined as "the average period of
use up to engine retirement or rebuild, whichever occurs first"
(emphasis added).[12] Under the modified full-life definition
it is the Agency's intent to retain this concept. Thus, it is
not EPA's intent that useful life should be only mileage to
rebuild when establishing the assigned useful-life values in
the modified full-life plan but rather that it should also
consider vehicle scrappage. Moreover, both "rebuild" and
"retirement" (scrappage) can be described as "owner actions"
and there is no mention of "need" for a rebuild in the above
definition. Available data indicate that the average LDT is
far more likely to be scrapped than to be rebuilt. An analysis
of the SDR survey data indicate that only about 12 percent of
all LDTs are ever rebuilt. [13] Thus, for 88 percent of the
vehicles in question, useful life is the mileage to
"retirement" rather than the mileage to rebuild, and exclusion
of scrappage data would overlook a significant body of data in
the calculation of average useful life.
While EPA acknowledges the point made by EMA and GM that
there may be some bias introduced into the scrappage rate data
by the presence of high mileage rebuilt engines, the percentage
of rebuilds (about 12 percent) is not large enough to have a
significant effect. Also, it should be recognized that there
are also biases in the other direction. Scrappage totals
include many low-mileage wrecks, for example, which tend to
lower the average. A major driveline failure may also result
in scrappage of a vehicle with additional miles remaining in
the engine because retirement and replacement would be more
cost-effective than repair. None of the available data on
average useful-life periods are without some drawbacks. With
the exception of HHDDEs where virtually every engine is rebuilt
at least once, neither rebuild data nor scrappage data is
adequate in and of itself to unequivocally establish
useful-life periods. Therefore, in light of these unavoidable
uncertainties, EPA has averaged data from a wide variety of
sources to minimize the effect of the deficiencies in the data
bases. These deficiencies were judged to be minor, and in some
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cases offsetting, thus allowing EPA to derive a representative
useful-life value.
While VW is correct that the data used in deriving the LDT
useful-life value do not include the newer, smaller light-duty
trucks, EPA sees no reason why the service lives of these
latter vehicles should differ significantly from those of the
standard size LDTs. While the lighter LDTs are powered by
smaller, less powerful engines, usually of 4 cylinders, and
operate at somewhat higher engine revolutions than conventional
LDTs, the trucks themselves are also lighter in weight and have
less payload and frontal area than their standard-size
counterparts. Few if any of these small pickups are likely to
be loaded to maximum capacity with any degree of regularity
and, as VW's comments indicated, the vast majority will in fact
be used for personal transportation, as are many standard
LDTs. EPA, therefore, concludes that there is no need for a
shorter assigned useful life for these vehicles. Since neither
VW nor any of the other commenters submitted any data to
substantiate the need for a shorter useful life for the smaller
LDTs, EPA will continue a common useful-life period for all
LDTs. LDT manufacturers also have the option of requesting an
alternative useful-life value in cases where the assigned
useful-life value is significantly unrepresentative of the
useful life for a particular engine family.
Therefore, the only change necessary to the LDT assigned
useful-life period calculation is to drop the SDR maximum
likelihood rebuild number, and reaverage the remaining four
sources. An average of the four sources remaining yields a
figure of 121,000 miles, so EPA will reduce the assigned useful
life for LDTs from 130,000 miles to 120,000 miles.
b. Heavy-Duty Gasoline Engines (HDGEs)
EPA rejects the arguments advanced by EMA and others
regarding the exclusion of scrappage-rate data in the HDE
useful-life calculation for the same basic reasons outlined
above in the LDT discussion. The SDR survey data indicate that
only 28 percent of the HDGEs are rebuilt or replaced, so again,
for the vast majority of HDGEs, useful life is the mileage to
retirement.
Although the above-mentioned Ford comment regarding SDR
survey data was made in reference to LDTs, the same general
considerations hold for HDGEs as well. The two HDGE rebuild
mileages from the SDR survey are not as disparate as the LDT
figures. However, if the SDR data are to be representative of
engine rebuild data in the HDGE average useful-life
calculation, the "maximum likelihood" value should be dropped,
since it includes non-rebuilt engines.
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EPA will also include rebuild data from the American
Trucking Association survey and estimates from the Arthur D.
Little draft truck usage study as suggested by EMA. Although
the contract under which the latter study was done was
terminated prior to completion, the useful-life estimates in
the report are reasonably consistent with other engineering
estimates, and EPA has no objection to inclusion of the A. D.
Little figures in the useful-life calculation. As shown below,
an average of the two scrappage rate values, the three rebuild
survey mileages, and the two engineering estimates results in a
useful-life period of about 108,000 miles. Therefore, EPA will
assign a value of 110,000 miles for HDGEs, rather than the
proposed value of 120,000 miles, based on the following
calculation:
Scrappage Rate Surveys:
Michigan Technological University 114,000
DOE 12 9,000
Rebuild Surveys:
SDR 124,000
Fleet 100,000
ATA 89,000*
Engineering Estimates:
* Sales-weighted average of trucks under 20,000 lbs. GVW (73
percent of sales) and of trucks over 20,000 lbs. GVW (27
percent of sales). These projected sales percentages were
multiplied by ATA mean survey mileages of 91,447 and
82,450 miles, respectively. If the modal or median values
are used, the sales-weighted rebuild mileages are 94,600
and 90,950 miles, respectively.
c. Heavy-Duty Diesel Engines
As in the Summary of the Comments, the EMA subclass
designations will be used throughout this section of the
analysis to avoid the confusion that would result from use of
both EPA and EMA terminology. The analysis will also be
oriented toward the EMA subclasses, since EPA is adopting them
over the subclasses as defined in the proposal. EPA agrees
with EMA that the Fleet vocational based rebuild figures used
in the MHDDE and LHDDE useful-life calculation may have
Little
Meyers
100,000
100,000
Average
108,000
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deficiencies. In any event, as stated in the above-mentioned
support memorandum concerning useful-life derivation, the LHDDE
subclass was assigned the same useful-life period as HDGEs, on
the judgment that LHDDEs should last about as long as the HDGEs
they were designed to replace. [14] The Ford comments and a
request by EMA to certify these engines to the HDGE useful life
provide additional support for this position.[15,16] Since the
HDGE useful-life period is based in part on the use of
scrappage-rate data, the EMA objection to its use also carries
oyer to the LHDDE subclass value. There are relatively few
data on the subject for LHDDEs. However, the Fleet survey
fbund that 43 percent of the non-sleeved engines in the survey
(the vast majority of which would be classified as MHDDEs) are
never rebuilt.[17] Most of the new LHDDEs are also non-sleeved
and are less expensive than MHDDEs, being designed to compete
with HDGEs. Since they are less costly to replace, and in some
cases are not designed to be rebuilt, it is likely that even
fewer LHDDEs than MHDDEs would be rebuilt. EPA will therefore
continue the linkage between LHDDEs and HDGEs, and establish
the assigned useful-life period for LHDDEs at 110,000 miles.
Turning now to MHDDEs, EMA felt that the figure of 203,000
miles quoted in the SDR survey for Class VI vehicles was too
large for the MHDDE subclass, because the Class VI vehicles
probably used some engines which would be considered as premium
HHDDEs. EPA concurs with EMA's assessment. Second, although
data in the Fleet article indicated that buses are typically
powered by MHDDEs, this application may not be representative
of MHDDE usage. Therefore, EPA accepts EMA's suggestion that
MHDDE useful life should be based in part on the average
non-sleeved engine mileage to overhaul reported in the Fleet
survey (175,000). The ATA survey rebuild mileage of 176,000
for diesel straight trucks also lends support to this figure.
An average of the sources suggested by EMA (including the SDR,
ATA, and Fleet, rebuild surveys and engineering estimates by
Little and Myers) yields an average rebuild mileage of 173,300
miles.
However, while EPA accepts the average of these data as
valid for the MHDDEs that are rebuilt, the Fleet survey also
indicates that an average of 43 percent of the non-sleeved
engines do not get rebuilt. This is a significant percentage
and must also be factored in to the determination of the useful-
* The straight truck data in the ATA survey included both
gasoline and diesel trucks. The median was 150,000 miles
and the mean was 170,470 miles. The relative values of
the median and the mode depict a disjointed data set.
Based on the HDGE analysis above, it was concluded that
the median value was relatively low due to the HDGEs. So
the modal value probably represented the diesel straight
trucks. Therefore, the 200,000-mile value was used.
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life period for MHDDEs. EPA expects that non-rebuilt engines
would be operated somewhat past the point where the average
rebuild would normally occur, as owners attempted to extract
the maximum service. The ATA survey provides a modal value of
200,000 miles for trade-in of straight trucks.[18]* Since few
owners are likely to go to the expense of a rebuild at 173,000
miles, and then trade in the truck 27,000 miles later, 200,000
miles is a reasonable estimate of useful life for non-rebuilt
engines.
Therefore, addition of 57 percent of 173,300 miles
(98,781) to 43 percent of 200,000 miles (86,000) yields a
weighted average of 184,781 miles, so EPA will establish a
period of 185,000 miles as the MHHDE assigned useful life.
Given the change in the HDDE classification approach from
gross vehicle weight to what is essentially an
application-based approach, there also is a need for a
reassessment of the assigned useful-life period for HHDDEs,
just as was done for MHDDEs. The heavy heavy-duty diesel
engine subclass originally proposed by EPA covered GVW Classes
VII and VIII trucks and buses, and these vehicles included some
engines that would now be classified as MHDDEs or even LHDDEs
under the EMA approach. Caterpillar's comments indicated, for
example, that its 3208 engine, which the manufacturer
considered an MHDDE, was sold "almost solely" in Class VII or
VIII GVW vehicles. [19] International Harvester Corporation,
which also manufactures LHDDE and MHDDEs, stated that "every
diesel engine" the company offers for sale could be found in
Class VII or VIII GVW vehicles.[20] The assigned useful-life
period for heavy heavy-duty diesel engines in the proposal
reflected this vehicle mix and is therefore understated for
HHDDEs under the EMA approach. With the adoption of EMA's
subclasses based on application rather than GVW, the HHDDE
subclass will now be predominantly premium-engines designed for
long-haul, high-mileage service applications, necessitating an
adjustment in the assigned useful-life period. The SDR Classes
VII and VIII data are not adequately representative of premium
HHDDEs to serve as the basis for the analysis since these
vehicles would use some MHDDEs, just as EMA asserted that the
Class VI SDR figure was overstated because it included some
HHDDEs. However the SDR survey determined a rebuild mileage of
303,000 for "long haul" usage engines, which would clearly
reflect HHDDEs. Also, the Fleet average rebuild mileage for
sleeved engines {281,000 miles) and the ATA mean rebuild
mileage for "tractors" (296,862 miles) are clearly
representative of the type of engine and operation in
question. An average of these three sources plus the A.D.
Little engineering estimate (290,000 miles) yields a mileage of
292,716 miles. Based on this average, EPA will assign a
useful-life value of 290,000 miles for this subclass.
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If the median or- modal values in the ATA survey (300,000
miles) were substituted for the mean, the resulting average of
the four sources would be 293,500 miles. Using the EMA
approach to the HDDE subclasses effectively addresses the
comment concerning the grouping together of Class VII and Class
VIII trucks in the heavy heavy-duty diesel subclass proposed by
EPA.
The final area to be considered is the number of years, as
opposed to miles, in the assigned useful-life values. EMA
s"tated that EPA's position appeared to be that a truly
representative years-to-rebuild value was not necessary "if an
accurate mileage value is prescribed."[21] EMA did not agree
with this position, saying that an accurate figure for
equivalent years to rebuild was necessary due to the fact that
many HDDEs accumulate a great many hours of running time
w:ithout accumulating many miles. Actually, EPA has never
maintained the position claimed by EMA. In most cases, the
period of years was roughly equivalent to miles of use as
described above. The Michigan Technological University (MTU)
vehicle mileage tables used in the EPA Emission Factors
Program, the National Highway Traffic Safety Administration
(NHTSA) mileage tables, and the Department of Energy "Highway
Fuel Consumption Model" (DOE) annual vehicle mileage tables
were consulted in determining years to the end of useful life
for all categories except Classes VII and VIII.[22] In the
latter case EPA found that while most applications were very
high mileage (i.e., the useful-life mileage would be
accumulated in 3-5 years), enough relatively low-mileage
applications would be included so that a considerably longer
period of years was necessary to be representative of their
full useful lives. Examples of these low-mileage applications
include concrete mixers, fire trucks, and garbage packers.
Although some of these applications will now likely be included
in the MHDD service class, EPA believes that some HHDDEs will
continue to be sold for this kind of use. An extended period
of years should not affect long-haul intercity vehicles for
which the useful-life mileage total will become the limiting
factor, but will allow a more representative useful-life period
for the lower mileage applications. Therefore, EPA will adjust
the useful-life year values for approximate equivalency with
the revised useful-life mileages, except for HHDDEs, which will
be assigned the same useful-life years as MHDDEs (i.e., 8
years).
Conclusions
Based on the above analysis, and the HDDE classification
system suggested by EMA, EPA finds it appropriate to revise the
useful-life values as follows:
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Mileage
Years
Proposed Final
Proposed Final
LDT
HDGE/LHDDE
MHDDE
HHDDE
130,000 mi. 120,000 mi.
120,000 mi. 110,000 mi.
200,000 mi. 185,000 mi.
275,000 mi. 290,000 mi.
12 years 11 years
10 years 8 years
10 years 8 years
10 years 8 years
EPA concludes that scrappage data should not be excluded
from the assigned useful-life calculations, as EMA suggested,
but has no objection to inclusion of other data as desired by
EMA. The assigned useful-life period will be the same for all
LDTs, rather than setting a shorter period for the lighter
4-cylinder vehicles as desired by VW and others. Finally, it
should be repeated that a manufacturer has the option to
request an alternative useful-life period for an individual
engine family if there is reason to believe that the assigned
useful-life value is unrepresentative.
Minor Issues
Summary of Comments
Manufacturers have raised a number of minor issues under
the modified full-life provisions. GM asked whether a
manufacturer would be expected to test engines after they were
worn out to determine a deterioration factor (DF) for the full
assigned useful life and also how a manufacturer would
determine the DF if the test engine failed before reaching the
assigned useful-life value. Mack Trucks suggested that bench
testing would be sufficient for checking the durability of HDDE
emission control components and that there would be no need for
full-life useful life. Ford presented its opinion that the
manufacturer's certification statement, to the effect that a
properly maintained engine will conform to the applicable
standards for its full useful life, must be qualified to take
into consideration engine wearout before the end of the
assigned useful-life period. The ATA wanted EPA to publish
useful-life values for all HDEs. Lastly, AMC stated that full
life would break the link allowing shared technology between
light-duty vehicles (LDVs) and LDTs, since LDTs would now
require more durable components. AMC predicted increased costs
to both manufacturers and consumers as a result of breaking
this LDV/LDT link.
Analysis of Comments
In response to GM's concerns, there will be no specific
durability testing requirement under modified full life. As
long as the manufacturers are satisfied that emissions will not
exceed the standard for the useful life of their
vehicles/engines, they are free to determine deterioration
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factors using any method desired, as long as good engineering
practices are followed. The bench testing option advanced by-
Mack Trucks might be a more cost-effective way to assess
component durability, for example, if the manufacturer felt
confident of the accuracy of that approach. However,. EPA
disagrees that such bench testing is adequate to eliminate the
need for the full-life useful-life requirement. EPA believes
that the full-life requirement is still necessary to provide
increased assurance of durable component design by holding the
manufacturer accountable for lifetime emissions compliance.
Bench testing represents one potential approach to durability
assessment which the manufacturers may choose.
With regard to Ford's point concerning the certification
statement, elimination of the useful-life labeling requirement
also removes the current compliance statement required for LDTs
and HDEs under 40 CFR 86.084-35. However, for vehicle/engine
classes where a single assigned useful-life value is specified,
that label is replaced by a general compliance label, as is
currently specified for LDTs and HDEs. This label states that
the vehicle/engine conforms to the applicable model year EPA
regulations. Since HDDEs are not all assigned the same
useful-life period, they will also be labeled to indicate the
subclass for which they are certified. Any LDT/HDE for which
an alternative useful-life value is approved by the
Administrator will also be labeled with the alternative
useful-life value. To address the Ford concern, EPA will
retain the current qualifying statement that "This engine's
actual life may vary, depending on its service applications."
Since engine-specific useful-life values . are replaced by
assigned useful-life periods, there should be no need to
publish individual useful-life data as requested by the ATA.
The assigned useful-life values for classes/subclasses are
published in this rulemaking. In addition, as outlined above,
HDDE manufacturers will be required to label their engines with
the service classes for which they are certified. As requested
by ATA, any vehicle/engine for which an alternative useful-life
value was approved would also be labeled with the alternative
value. Since ATA!s interests seem to be primarily in the area
of HDDEs which will all be labeled with the subclass as a
matter of course, and since alternative useful-life values will
be indicated if applicable, EPA feels ATA's needs will be
addressed by the above measures.
Finally, EPA does not believe the impact of full-life
useful life will be so great as to inhibit the sharing of
technology between LDVs and LDTs, as AMC suggests. It is
hardly cost-effective to redesign a component or design a
replacement for it and then continue to produce the old one in
parallel with production of the new or redesigned component.
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The Agency finds it difficult to believe that any manufacturer
would choose this course of action, particularly since it
provides a much narrower base for amortization of development
and tooling costs than would application of the component to
the entire product line. Since the applications and technology
are basically similar for both LDVs and LDTs, EPA believes that
commonality of components will continue to be standard
practice. If the durability of some of these components
improves as a result of the full-life requirement for LDTs, it
will result in an additional benefit to the LDV buyer and
improve the emissions of the LDV. There is no reason, however,
why separate components need be produced for LDVs and LDTs.
Conclusions
Most of the minor certification issues require no action
on EPA's part. The qualifying statement on the label that
average useful life will vary according to service application
will address Ford's concerns. ATA's request for publication of
the assigned useful-life values is addressed by the values
published in the rulemaking and by the labeling requirement for
HDDE subclasses and for alternative useful-life periods. AMC's
fear that full-life useful life will break the traditional
technology link between LDVs and LDTs appear overstated and EPA
rejects the idea, that any duplication of effort or waste of
resources will result.
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References
1. Summary and Analysis of Comment to the NPRM, 1983
and Later HDEs, pp. 105-110, December 1975.
2. Summary and Analysis of Comment to the NPRM, 1983
and Later LDTs, p. 1-3, May 1980.
3. "Report of the Committee on Public Works, 94-717,"
Legislative History of the CAA Amendments of 1977, Vol. 3, p.
671, May 10, 1977.
4. "The Clean Air Act as Amended, August 1977," Ser.
95-11, p. 11, November 1977.
5. Harley-Davidson Motor Company, Inc. vs. EPA, U.S.
Court of Appeals, D.C. Circuit, No. 77-1104, March 9, 1979.
6. See Reference 4, p. 122.
7. "House of Representatives Report 95-564," 75th
Congress, 1st Session, p. 164, 1977.
8. EPA Memorandum, "Summary of the February 18, 1983
HDE/LDT Useful-Life Workshop," Terry P. Newell, March 1, 1983.
9. Fleet Maintenance and Speci fying, Vol. 7, No. 3,
March 1981, pp. 39-43.
10. "Report on Commerical Trucking Diagnostic Needs
Survey," American Trucking Associations, Inc., c.1981.
11. Draft Report "HD Vehicle Engine Service Accumulation
Cycle, A. D. Little, Inc., EPA Contract 68-03-2712, April 1977.
12. 40 CFR 86.084-4(b)(1).
13. "Calculation of Total Rebuild Percentages for LDTs
and HDGEs," EPA Memorandum from Robert J. Johnson, July 25,
1983.
14. "Determination of Useful-Life Values for Light-Duty
Trucks and Heavy-Duty Engines," EPA Memorandum from Robert J.
Johnson, December 13, 1982.
15. Response to January 12, 1983 NPRM, Public Docket
A-81-11, IV-D-86, p. 16, April 18, 1983.
16. Letter from Thomas C. Young to Kathleen M. Bennett,
Office of Air, Noise and Radiation, May 3/ 1982.
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References (cont'd)
17. Fleet Maintenance and Specifying, Vol. 7, No. 7, May
1981.
18. See Reference 9, p. 6.
19. Caterpillar Response to January 12, 1983 NPRM,
Public Docket A-81-11, IV-D-77, p. 4, April 13, 1983.
20. International Harvester Response to January 12, 1983
NPRM, Public Docket A-81-11, IV-D-81, p. 23, April 18, 1983.
21. EMA Response to January 12, 1983 NPRM, Public Docket
A-81-11, IV-D-83, p. 53.
22. "Conversion of Useful-Life Mileages to Periods of
Years," EPA Memorandum, Robert J. Johnson, July 25, 1983.
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3. Issue: Alternative Test Cycles
A. The Real Time Cycle for Heavy-Duty Diesel Engines
Summary of the Issue
An alternative heavy-duty diesel test cycle, the Real Time
Cycle (RTC), has been developed by the Caterpillar Tractor
Company (Caterpillar). It was developed in response to
industry-wide concern over the methodology used to generate the
EPA cycle and its resulting representativeness.
Summary of Comments
Most manufacturers and the Engine Manufacturers
Association (EMA) have made specific recommendations concerning
the use of the RTC for certification testing. Some of the
recommendations, however, have changed over time as additional
data were gathered on the RTC. A brief review of the
chronology of events is appropriate for this discussion.
The EMA and member companies recommended in April 1982
that EPA adopt as a test option the use of the RTC. This
recommendation was based upon the industry's concern about the
representativeness of the EPA cycle.
Shortly thereafter, EPA reviewed the technical basis for
the creation of the RTC. (Part of EPA's earlier analysis is
reproduced below.) EPA also reviewed the available data base
wherein emission results from both cycles were compared. At
the time, about 30 comparative data points were available.
EPA's draft analysis noted that a net difference in emissions
existed between the test cycles, and recommended that the
applicable emission standards be adjusted to account for the
offset. This was recommended so as to preclude an effective
relaxation of the emission requirements promulgated on January
21, 1980. EPA's original analysis (see Appendix, Chapter 5 of
the Transient Test Study) was distributed for public comment in
early summer 1982.
The EMA and member companies reviewed EPA's draft
analysis, and over time, in both informal and formal
communications, took issue with two of EPA's conclusions.
First, EMA disputed the need for an emission standard
adjustment. The argument was made that the heavy-duty diesel
cycle was never used in the standards development process, and
the use of a specific diesel cycle is decoupled from the level
of the standards. (The heavy-duty gasoline engine cycle was
used to derive the statutory emission standards.) Secondly, if
an adjustment were to be made, EMA disagreed with the
methodology EPA used to derive the equivalently stringent
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standard. EMA proposed a methodology which yielded an
RTC-based hydrocarbon (HC) emission standard of 1.20 grams per
brake horsepower-hour (g/BHP-hr), using the latest available
data. EMA and its member companies formalized their position
in a May 13, 1983 submission to EPA. They also recommended,
contrary to earlier recommendations, that only a single test
cycle bp used for certification. If the RTC cycle was not made
available with a HC standard of 1.2 g/BHP-hr, the industry
preferred the use of the EPA cycle at the 1.3 g/BHP-hr HC
standard.
Analysis of Comments
in this analysis, we address the construction,
representativeness, and relative stringency of the RTC.
Methodologies for emission standard adjustments are also
evaluated, as is the justification for such an adjustment.
Finally, the selection of a certification test cycle is made.
Cycie Development!3]
Caterpillar developed the RTC because of concern over the
accuracy of simulation of in-use truck operation represented by
the EPA cycles. This concern stemmed from alleged
instrumentation problems in the CAPE-21 project which they
argued resulted in a significant amount of questionable data
being accepted into the data base, and from the methodology EPA
used to generate the cycle. Caterpillar's objectives in
developing the RTC were to generate a cycle from the portion of
the CAPE-21 data base which it considered valid, and to
construct- the cycle so it better represented its judgment of
real-world truck operation.
The entire data base was first edited to remove what
Caterpillar believed to be questionable data. This editing
left 23 truck-days of data, or about 25 percent of the original
data base. statistical parameters were then chosen to
characterize the edited data base. These were mean values and
cumulative distributions of percentage rpm, percentage power,
and positive percentage rpm. The percentage idle time and
distribution in length of idle were also used. These
statistical parameters then became the target values for the
construction of the new test cycle.
To construct the new test cycle, the data were broken down
into the smallest elements which did not interrupt the normal
driving sequence. These elements were defined as the vehicle
operational events which occurred between vehicle stops. The
elements were then assembled into trial test segments which
matched, as closely as possible, the desired statistics of the
categories they represented. The categories were: Hew York
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Freeway (NYP), New York Non-Freeway (NYNF), Los Angeles Freeway
(LAF), and Los Angeles Non-Freeway (LANF). The idle time and
category weighting were adjusted to match the original CAPE-21
data base, since it was judged unlikely that instrument error
would change these parameters. The trial test segments were
then tested against the data base for maximum deviation of
cumulative distributions and then were compared visually. The
best cycles were selected and assembled into an entire driving
cycle.
The result was a heavy-duty diesel engine (HDDE) driving
cycle, the "Real Time Cycle," which matched very closely the
statistics of the edited CAPE-21 data base, and which the
diesel engine manufacturers believed was more representative of
in-use truck operation than the EPA cycle.
Statistical Analysis
A comparison of the target statistics from the edited data
base, the RTC statistics, and the EPA cycle statistics is shown
in Table 3-1. Additional statistics from the RTC, EPA cycle,
and the original CAPE-21 data base are listed in Table 3-2.
The most important statistical differences between the RTC and
the EPA cycle are:
1. The RTC includes a NYF segment, while the EPA cycle
does not.* (The NYF segment is higher in mean percentage rpm
and higher in mean percentage power than the NYNF segment.)
2. The RTC is 5.2 percent higher in mean percentage
power, overall, than the EPA cycle.
3. The RTC is 4.8 percent lower in percentage idle
time, overall, than the EPA cycle.
4. The sequential ordering of the cycle segments on the
RTC is LANF, LAF, NYF, and NYNF. The ordering on the EPA cycle
is NYNF, LANF, LAF, NYNF.
The statistical differences cited here may or may not
affect engine emission levels. A potentially significant
factor is that the observed engine work done over the test
cycle (BHP-hr) is higher by 16-18 percent on the RTC.
Furthermore, the reordering of the segments in the RTC permits
the engine to operate in the high power LAF mode earlier in the
cycle, which may lead to an earlier engine warm-up (although
EPA omitted the NYF segment because invalid data had been
included in the data base and the weighting for this
segment was small compared to the other segments. [4]
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Table 3-1
Target, RTC, and EPA Cycle Statistics [3]
Los Angele
s Non-Freeway
Los Angeles Freeway
Target Real Time EPA
Target
Real Time
EPA
Average rpm (%)
40.7
41.8 43
80.0
83.5
83
Average Power
(%)
24.1
25.9 26
58.9
56.4
56
Average Positive
Acceleration
4.6
5.7 6.1
1.9
1.2
2.4
Idle Time (%)
35.0
32.7 34
2.0
1.4
2.3
Category
Weighting
23.7
27.3 25.0
26,3
25.1
25.0
Los Anqeles Non-Freeway
Los Anqeles Freeway
Target Real Time EPA
Target
Real Time
EPA
Average rpm (%)
41.5
47.1
17.7
19.8
20
Average Power
(%)
Average Positive
Acceleration
41.0
2.8
54.4
4.6
19.4
3.8
22.3
3.6
16
5.6
Idle Time (%)
19
21
51.0
51.0
55
Category
Weighting
9.0
5.9 0
41.0
Overall
41.7
50.0
Target
Real Time
EPA
Average
rpm <%)
41.7
43.4
41.5
Average
Power (%)
32.8
33.7
28.5
Average Positive
Acceleration
3.9
4.2
4.6
Idle Time (%)
31.4
31.8
36.6
-75-
-------
RTC, EPA
Table 3-2
Cycle, CAPE-21 Data
Base Statistics
Parameter
RTC
EPA
CAPE-21
Torque
Mean (%)
30.57
28.32
27.00
Percent of
Cycle Time
Acceleration
(%)
18.21
15.68
15.10
Deceleration
(%)
18.37
16.85
15.25
Cruise (%)
22.48
20.43
18.75
Motor (%)
7.98
11.43
15.00
Idle (%)
32.96
35.61
35.00
RPM
Mean (%)
42.78
41.52
41.75
Percent of
Cycle Time
Acceleration
(%)
23.45
21.77
21. 50
Deceleration
<%)
22.48
21.93
19.50
Cruise (%)
19.74
16.10
19.50
Idle (%)
34.33
40.20
39.00
-76-
-------
operation in the LAF segment of the RTC is initially cooler
than on the EPA cycle) . Inclusion of the NYF segment in lieu
of another NYNF segment is one obvious reason why the RTC
BHP-hr is higher than that of the EPA cycle.
Test Cycle Correlation
Heavy-duty diesel engine manufacturers and EPA have now
tested many engines on both the RTC and the EPA cycle for the
purpose of comparing emissions results. All of the available
data have been collected and are summarized in Table 3-3.
Results are also plotted in Figures 3-1, 3-2, and 3-3. Since
typical diesel carbon monoxide (CO) emissions are much lower
than statutory levels, this pollutant comparison was not
included. Immediately obvious is the fact that emission levels
are different between the candidate test cycles.
The HC emissions difference between the test cycles is
explainable and expected. A decrease in brake specific HC
emission rates at higher engine loads is typically observed on
diesel engines. Consider the following mechanism for such an
observation: in diesel engines, HC emissions are in large part
attributable to residual fuel in the injector sac. The sac
volume is constant regardless of the amount of fuel injected;
as the load is increased (i.e., more fuel is injected), the
mass rate of HC emissions from the sac remains constant.
However, the brake specific rate of HC emissions (g/BHP-hr)
decreases at higher loads since the denominator (power-hour)
increases while the numerator (mass HC) remains the same. This
could explain most of the difference in HC emissions, given
that the RTC is a higher power test cycle and that both cycles
exercise the engine in fundamentally the same way.
The constant residual sac volume is likely not the only
mechanism by which emissions from each cycle are different.
However, further discussion of exact mechanisms at this point
is not important. What is important is the fact that the RTC
cycle correlates very well with the EPA cycle (and vice versa)
for many different engines. This indicates that emissions from
one cycle can be accurately predicted from those of the other.
The excellent correlation also indicates that both cycles
should be comparable in the ability to predict in-use emission
reductions, and that there is no inherent advantage in using
one cycle over the other. Given the difference in cycle
generation methodologies and the correlatable emission results,
and the reasonable presumption that the HC emissions offset is
primarily attributable to the difference in load factor between
the cycles, EPA concludes that both cycles are comparably
representative. Each by itself would be technically acceptable
for certification testing.
-7 7-
-------
Table 3-3
Summary of Bnissions Data EPA Cycle vs. Real Time Cycle
Number and Contained Cold/Hot Start Hot Start Only
Engine/
Test Number[a]
Test Lab
Cycle
Type
(CS)
of Tests
(HS)
Regressions
BC
(q/BHP-hr)
NOx
(q/BHP-hr)
Part.
(q/BHP-hr)
Regressions [b]
IC
(q/BHP-hr)
NOx
(g/BHP-hr)
Part
(q/BHP-1
Mack ETSX-676[c]
EPA
EPA
RTC
4
4
—
~
1,8,10
.65
.55
8.40
8.56
.752
.777
Cummins
VTB-903 [c]
EPA
EPA
KPC
4
4
—
—
•—
1,8,10
1.60
1.27
5.07
5.01
.544
.504
IHC DT-210
IHC[e]
EPA
RTC
1-3
1-3
2-7
2-7
1,2,3,4,
8,9,10,11
.89
.78
7.20
6.80
—
—
—
—
IHC DTI-210
IHC
EPA
RTC
1-3
1-3
.2-7
2-7
1,2,3,4,
8,9,10,11
1.07
• 95 [i]
4.15
4.16
—
—
—
—
IHC OTI-180
IHC
EPA
fox:
1-3
1-3
2-7
2-7
1,2,3,
4,5,6,7,
8,9,10,11
1.18
1.06
4.94
4.73
5,6,7
1.14
1.05
—
—
IK 9.0L
IHC
EPA
PTC
1-3
1-3
2-7
2-7
1,2,3,4,5,
6,7,8,9,
10,11
2.03
1.90
7.18
7.52
5,6,7
2.04
1.90
;;
"
Cumnins
#l[f]
Cumnins
EPA
RTC
2
2
—
—
—
1,8,9,10
.55
.48
7.50
7.46
.46
.43
Cummins
#2
Cummins
EPA
RTC
2
2
—
—
--
1,8,9,10
1.19
.91
8.10
7.92
.66
.66
Cummins
#3
Cummins
EPA
RTC
2
2
—
—
--
1,8,9,10
.87
.63
7.37
7.29
.70
.56
Cumnins
#4
Cummins
EPA
RTC
2
2
—
—
~
1,8,9,10
.94
.67
4.63
5.42
.94
.94
Cat 3208
IHC
EPA
PTC
5
4
12
6
—
--
—
1
1.30
.84
7.68
8.57
.70
.60
-------
Table 3-3 (cont'd)
Summary of Emissions Data EPA Cycle vs. Real Time Cycle
Number and
Combined Cold/Hot Start
I
-j
I
Engine/
Test Number[a]
Test Lab
Cycle
Type of
(CS)
Tests
(HS)
Regressions
HC
(q/BHP-hr)
NOx
(q/BHP-hr)
Part.
(q/BHP-hr)
Reqressions[b]
fC
(q/BHP-hr)
NOx
(q/BHP-hr)
Part.
(q/BHP-hr)
Mack #1[g]
Mack
EPA
RTC
lf2[d],8,
9,10,11
.46
•41
5.6
5.9
.51
.46
__
Mack #2
Mack
EPA
KIC
1/2[d],8,
9,10,11
.55
.46
7.8
8.4
.79
.69
—
—
—
Mack #3
Mack
EPA
RIC
If 2 [d] ,8,
9,10
1.10
.87
10.3
9.0
.85
.69
—
—
—
Cat 3208 [c)
IHC
EPA
KIC
5
4
11
6
1,2,5,
8,10,11
1.30
.85
7.59
8.59
.70
.60
5
1.24
.81
—
—
Mack ETSX-
676 [c]
Cat
EPA
FTC
2
1
12
7
1,2,3,
4,5,6,8,10
.73
.65
6.82
7.62
.53
.63
5,6
.74
.64
--
—
IHC DCT-
466B [c]
Cat
EPA
RIC
2
1
15
6
1,2,3,
4,5,8,10
1.00
.90
4.44
4.30
.69
.70
5
.95
.90
—
—
Cat 3208
Cat
EPA
RTC
5
1
11
7
1 [h] ,2,3,
4 [h] ,5,6,7,
8,9,10,11
.97
.88
8.40
8.79
.86
.88
5,6,7
.92
.85
—
—
Cat 3406
Cat
EPA
RTC
3
1
14
6
1,2,3,
4,5,6,7,
8,9,10,11
.49
.40
4.82
5.00
.83
.73
5,6,7
.48
.39
—
—
Cat 3208
Cat
EPA
RIC
2
3
6
8
1,2,3,
4,5,6,7,8,
9,10,11
1.07
.98
9.11
9.24
.854
.712
5,6,7
1.07
.97
—
—
Cat 3208
Model 1
Cat
EPA
RIC
2
5
3
5
1,2,3,4,5,
6,7,8,9,10,11
1.04
.88
14.13
13.96
1.04
.820
5,6,7
1.02
.88
—
--
-------
Table 3-3 (cont'd)
Summary of Emissions Data EPA Cycle vs. Real Time Cycle
Engine/
Test Number[a]
Cat 3208
Model 2
Cat 3406
IHC DT-466
(210)
Cat 3406,
Model 1
Cat 3406,
Model 2
Cat 3406,
Model 3
Cuirmins
VTB-903 [c]
DDA 8V-92,
Model 1
Test fr^h Cycle
Number and
Type of Tests
(CS) (HSF
Combined Cold/Hot Start
Cat
Cat
IHC
Cat
Cat
Cat
DDA
DDA
EPA
RFC
EPA
KPC
EPA
KPC
EPA
KIC
EPA
RTC
EPA
RTC
EPA
FTC
EPA
RTC
Regressions
1,2,3,4,5,
6,7,8,9,10,
11
1,2,3,4,
5,6,7,8,9,
10,11
2.5.6.7,
8,9,10,11
1,2,3,4,
5,6,7,8,9
10,11
1,2,3,4,
5,6,7,
8,9,10,11
1,2,3,4,
5.6.7.8,
9,10,11
HC
(g/BHP-hr)
2.70
2.40
.48
.37
1.02
.95
.60
.47
.57
.50
.89
.77
NOx
(q/BHP-hr)
6.38
6.42
7.62
7.26
11.82
11.56
4.03
3.78
4.12
3.64
Part.
(q/BHP-hr)
1.24
.974
.782
.653
Hot Start Only
.726
.601
1.79
1.33
2.20
2.27
Regressions[b]
5,6,7
5,6,7
5,6,7
5,6,7
5,6,7
5,6,7
1,8,10
1,8,9,10
HC
(q/BHP-hr)
2.73
2.38
.45
.35
NOx
(q/BHP-hr)
Part.
(q/BHP-hr)
.98
.94
.52
.43
.53
.49
.82
.74
1.98
1.73
.81
.72
5.07
4.80
4.60
4.26
-------
Table 3-3 (cont'd)
Summary of Bnissions Data EPA Cycle vs. Real Time Cycle
Number and Combined Cold/Hot Start Hot Start Only
Engine/
Test Number[a)
Test Lab
Cycle
Type of Tests
(CS) (HS>
Regressions
HC
(q/BHP-hr)
NCbc
(q/BHP-hr)
Part.
(q/BHP-hr)
Reqress ions[b]
HC
(q/BHP-hr)
NOx
(g/BHP-hr)
Part.
(q/BHR-hr)
DDA 8V-92,
Model 2
DDA
EPA
RFC
3
3
—
—
—
1,8,9,10
.68
.73
8.38
7.69
—
OCA 8V-71TA[C]
Cat
EPA
RFC
2,3,4,5,6,
8,10
.63
.61
—
—
5,6
.63
.62
—
--
IHC 466B[c]
Cummins
EPA
'FTC
—
—
--
8,10
.66
.62
4.01
4.09
.76
.77
DDA 8.2L
DDft
EPA
KIC
3
3
—
—
—
1,8,9,10
1.14
.92
5.78
5.44
—
Currinins
VTB-903
Cummins
EPA
KIC
2,8,9,10,11
1.66
1.37
4.97
5.14
.91
.76
—
—
—
IK DT-466 [c]
EPA
EPA
PTC
—
—
—
8,10
.64
.62
3.53
3.53
.65
.66
DDA 8V-71TA
DDA
EPA
PTC
2,8,9,10,11
.55
.59
6.75
6.96
.35
.33
—
—
--
Mack EISX-676
Mack
EPA
ETC
—
—
—
8,9,10
.78
.71
7.86
7.4
.56
.53
IHC OT-466
IHC
EPA
FTC
2,5,6,7,
8,9,10,11
.75
.63
—
—
5,6,7
.68
.62
—
—
3241
3242
Cunmins
EPA
FTC
1
1
—
—
8,9,10
.88
.69
5.45
5.57
—
3261
3263
Cumnins
EPA
FTC
1
1
—
8,9,10
1.3
2.51[j]
5.90
5.80
—
-------
Engii
it NUI
3301
3302
3321
3322
3341
3342
3391
3393
3413
3414
3461
3463
3501
3502
3531
3532
3612
3613
3641
3642
Test Lab Cycle
Cummins
Cummins
Cummins
Cummins
Currmins
Cummins
Cummins
Cumnins
Cuirmins
Cummins
Number and
Type of Tests
(CS) (HS)
Table 3-3 (cont'd)
Summary of Emissions Data EPA Cycle vs. Real Time Cycle
Combined Cold/Hot Start
HC NOx Part.
Regressions (q/BHP-hr) (q/BHP-hr) (q/BHP-hr)
Hot Start Only
Regressions[b]
HC NOx
(q/BHP-hr) (q/BHP-hr)
EPA 1
KDC 1
8,9,10
.89
.68
5.80
5.84
EPA 1
KDC 1
8,9,10
.84
.64
6.56
6.53
EPA 1
RTC 1
8,9,10
.91
.73
6.53
6.42
EPA 1
FTC 1
8,9,10
1.08
.60
6.96
6.63
EPA 1
KIC 1
8,9,10
.84
.64
7.16
6.98
EPA 1
ETC 1
8,9,10
.82
.58
6.68
6.77
EPA 1
RTC 1
8,9,10
.80
.65
5.37
5.66
EPA 1
RTC 1
8,9,10
.83
.72
4.42
4.53
EPA 1
FTC 1
8,9,10
.77
.61
7.40
7.38
EPA 1
FTC 1
8,9,10
.72
.57
7.32
7.28
-------
Engii
it Nu]
3761
3762
3742
3743
3761
3762
3781
3782
3791
3792
3841
3842
3852
3853
3861
3862
3871
3872
3881
3882
3961
3962
Table 3-3 (cont'd)
Sunmary of amissions Data EPA Cycle vs. Fteal Time, Cycle
Test Lab Cycle
Cunmins
Cummins
Cumnins
Cumnins
Number and
Type of Tests
(CS) (HS)
Combined Cold/Hot Start
BC NOx Part.
Regressions (g/BHP-hr) (q/BHP-hr) (g/BHP-hr) Regress ions{jbl
Hot Start Only
HC NOx
(g/BHP-hr) (g/BHP-hr)
Cuirmins
Cuirmins
Cummins
Cuirmins
Cunmins
Cunmins
Cunmins
EPA 1
RFC 1
8,9,10
2.07
1.58
6.13
6.27
EPA 1
FTC 1
8,9,10
.93
.72
6.77
7.01
EPA 1
KIC 1
8,9,10
.89
.65
6.24
6.11
EPA 1
RFC 1
8,9,10
1.58
.98
6.72
6.80
EPA 1
PTC 1
8,9,10
.26
.17
6.05
6.10
EPA 1
RFC 1
8,9,10
.88
.54
7.86
8.11
EPA 1
FTC 1
8,9,10
.85
.67
7.19
7.52
EPA 1
KIC 1
8,9,10
.60
.47
7.22
7.54
EPA 1
KIC 1
8,9,10
.56
.43
7.49
7.54
EPA 1
KIC 1
8,9,10
.65
.53
7.35
7.27
EPA 1
KIC 1
8,9,10
.74
.59
6.55
6.58
-------
Table 3-3 (cont'd)
Summary of Bnissions Data EPA Cycle vs. Real Time Cycle
Number and Combined Cold/Hot Start Hot Start Only
Engine/ Type of Tests fC NQx Part. HC NOx Part.
Tfest Number[a] Test Lab Cycle (CS) (HS) Regressions (g/BHP-hr) (g/BHP-hr) (g/BHP-hr), Regressions[b] (g/BHP-hr) (g/BHP-hr) (g/BHP-hr)
4011
4012
Cumnins
EPA 1
KTC 1
8,9,10
.69
.50
6.36
6.38
4031
4032
Cumnins
EPA 1
RIC 1
8,9,10
.65
.53
7.67
7.92
4042
4043
Cummins
EPA 1
RTC 1
8,9,10
1.48
1.18
6.82
6.91
4051
4052
Cunmins
EPA 1
KTC -1
8,9,10
.67
.53
7.43
7.55
4081
4082
Cummins.
EPA 1
KTC 1
8,9,10
.86
.72
6.33
6.44
4245
4246
Cumnins
EPA 1
KIC 1
8,9,10
.83
.66
3.83
4.74
4261
4262
Cummins
EPA 1
KIC 1
8,9,10
.75
.63
6.57
6.90
4331
4332
Cumnins
EPA 1
RTC 1
8,9,10
.77
.68
6.05
6.26
4351
4352
Cunmins
EPA 1
KIC 1
8,9,10
.88
.74
5.91
5.62
4381
4382
Cummins
EPA 1
KIC 1
8,9,10
1.02
.77
6.43
6.59
4401
4102
Cumnins
EPA 1
KDC 1
8,9,10
.76
.53
6.39
6.29
-------
Table 3-3 (cont'd)
Summary of Emissions Data EPA Cycle vs. Real Time Cycle
Number and Combined Cold/Hot Start Hot Start Only
Engine/ Type of Tests HC NOx Part. fC NOx Part.
Test Number fa) Test Lab Cycle (CS) (HS) Regressions (g/BHP-hr) (q/BHP-hr) (g/BUP-hr) Regressions [b] (g/BHP-hr) (g/BHP-hr) (q/BHP-hr)
4451
4452
Cummins
EPA 1
KIC 1
8,9,10
.61
.58
6.30
6.23
4521
4522
Cummins
EPA 1
KIC 1
8,9,10
.75
.56
6.47
6.48
4561
4562
Cummins
EPA 1
RTC 1
8,9,10
.72
.63
4.09
4.14
4581
4582
Cummins
EPA 1
rac 1
8,9,10
.66
.56
4.36
4.35
4611
4612
Cumnins
EPA 1
FTC 1
8,9,10
.80
.65
3.93
3.99
3661
3663
Cujtmins
EPA 1
KIC 1
8,9,10
.87
.65
6.13
6.32
4661
4662
Cummins
EPA 1
FTC 1
8,9,10
.79
.56
6.94
6.01
4801
4802
Cummins
Cummins
EPA 1
FTC 1
8,9,10
.86
.69
8.88
9.06
4721
4722
Cummins
Cummins
EPA 1
FTC 1
8,9,10
.91
.68
6.19
6.24
4773
4774
Cummins
Cummins
EPA 1
FTC 1
8,9,10
.72
.59
7.91
7.70
4713
4714
Cummins
Cummins
EPA 1
FTC 1
8,9,10
.98
.76
6.20
5.73
-------
Table 3-3 (cont'd)
Summary of Emissions Data EPA Cycle vs. Real Time Cycle
Number and Combined Cold/Hot Start Hot Start Only
Engine/ Type of Tests HC NQx Part. HC NOx Part.
Test Number [a] Test Lab Cycle (CS) |