TP690.45
.E44
1987x
United States Environmental
Protection Agency
Office of Mobile Sources
Washington, DC 20460
United States Department
of Agriculture
Office of Energy
Washington, DC 20250
EPA
I USDA
A Joint Report
April 1987
Effects of Using Unleaded
and Low-lead Gasoline, and
Non-lead Additives on
Agricultural Engines
Designed for Leaded Gasoline
OOOR87900
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Effects of Using Unleaded and
Low-lead Gasoline, and Non-Lead Additives
on Agricultural Engines Designed for
Leaded Gasoline
April 1987
U.S. Environmental Protection Agency
U.S. Department of Agriculture
Washington, D.C.
U.S. Environmental Protection Agency
Region 5, Library (5PL-16)
2oO S. Dearborn Street, Room 1670
Chicago, IL 60604
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Table of Contents
Page
I. Background 1
II. Scope of Study 3
A. Dynamometer Testing 4
B. Farm Engine-Use Survey ..... 5
C. Cylinder Head Survey 6
III. Agricultural Machinery Testing on Engine Dynamometers 7
A. Test Design , , 7
B. Engines Tested , 10
C. Dynamometer Testing Limitations 11
IV. Results of Dynamometer Testing 13
A. Tests of Leaded Gasoline 13
B. Tests of Unleaded Gasoline 16
C. Tests of Low-lead Gasoline 24
D. Tests of Non-lead Additives 26
V. Results of the Farm Use Survey and Survey of Valve Seats 31
Appendices
Appendix 1 Exhaust Valve Seat Recession by Cylinder 38
Appendix 2 Consultants Evaluations of Engine Testing Performed
by NIPER 64
Appendix 3 Duty Cycles Used in Engine Tests 72
Appendix 4 Engines Tested 75
Appendix 5 Farm Engine-Use Survey Form 77
Appendix 6 How to Obtain Documents Referred to in this Report . 79
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I. Background
Due to health concerns from public exposure to lead in
automotive exhaust, the Environmental Protection Agency (EPA)
undertook a lead phasedown program in the early 1970's to
remove lead from gasoline. At that time, refiners used
approximately 2.5 grams per leaded gallon (gplg). In 1982
the amount of lead permitted in leaded gasoline was reduced
to 1.10 gplg. On March 7, 1985, EPA further reduced the
allowable level to 0.50 gplg, effective July 1, 1985 and
0.10 gplg on January 1, 1986. A complete ban on leaded
gasoline has been considered for as early as 1988. The
Agency has not proceeded with a total ban because of a concern
that older engines designed for leaded gasoline may suffer
premature valve seat wear if required to use unleaded gasoline
exclusively, and a maior health effect study of lead exposure
required further review.
The Agency determined that 0.10 gplg would be satifactory
to protect those older engines, based on testing that had
been done in the early 1970's. Results of those tests are
summarized in Costs and Benefits of Reducing Lead in Gasoline--
Final Regulatory Impact Analysis (EPA-230-05-85-006,
February, 1985). Generally, these tests showed that certain
engines when operated on unleaded fuel for continuous high
speeds, experienced valve seat recession. However, at lower
speeds, valve seat recession was greatly reduced. One study
showed that between 0.04 and 0.07 gplg would be satisfactory
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to protect valve seats. Based on this and other studies,
EPA concluded that 0.10 gplg would be sufficient to protect
exhaust valve seats from recession in engines designed for
leaded gasoline.
The farming community expressed a concern that older
farm engines designed to operate on leaded gasoline may
experience engine damage if operated on low-lead or unleaded
gasoline. In response to that concern, Congress required a
study to be conducted under Section 1765 of the Food Security
Act of 1985 (P.L. 99-198) (Act).
The Act required the Administrator of EPA and the
Secretary of Agriculture (USDA) to "jointly conduct a study
of the use of fuels containing lead additives and alternative
lubricating additives," on gasoline-powered agricultural
machinery. The study was to analyze the potential for
mechanical problems (including but not limited to valve seat
recession) that may occur with the use of other fuels in farm
machinery. The Secretary of Agriculture was to specify the
types and items of agricultural machinery to be included in
the study and all testing of engines was to reflect actual
agricultural conditions, including revolutions per minute
and loads placed on the engines.
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II. Scope of study
The study's overall goals are to determine the risk to
engines if gasoline is limited to either low-lead or unleaded
and to evaluate alternative additives to lead. The study
has a complex design hecause the relationship between gasoline
type and engine durability is a function of both engine
design and usage patterns. The primary engine component at
risk with a fuel change is the exhaust valve seat. This
wears by receding into the cylinder head. If wear is severe
enough, the exhaust valve eventually will not seat properly
and engine failure will follow. Factors influencing the
risk of wear include engine speed (rpm), load, temperature
and cylinder head design. Information is needed on all of
these factors to assess the risk of engine failure.
Little information was available about rpm and load
levels for agricultural equipment under actual use conditions.
Further, concern arose that since most of the equipment is
not new, the valve seats could have been modified during
overhauls so that original equipment specifications would no
longer accurately reflect the type of valve seats in use.
The study was divided into three areas: Agricultural
machinery testing on engine dynamometers; farm use survey of
gasoline-powered equipment; and field measurement of the type
of valve seat material in exhaust valve seats in gasoline-
powered tractors.
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A. Dynamometer Testing
The design of the testing portion of this study was
initiated with a letter from EPA on December 6, 1985 to 25
potential commenters from EPA, USDA, the American Farm Bureau
Federation (AFBF), tractor manufacturers, university professors,
and independent consultants. The letter forwarded a statement
of work suggested for the study. Comments were received from
most of the recipients of the letter and suggested a wide
variety of changes. A meeting was held on January 27, 1986
with all commenters who wished to attend to discuss the
program and reach a consensus on engines to test, duty cycles
and other details of the test program. Twenty-one commenters
attended the meeting. Based on discussions at this session,
EPA revised the statement of work and sent it back to the
commenters for a final review. Through this procedure and
further contacts with engine manufacturers and others, EPA
and USDA representatives agreed on a test procedure for
tractors, combines, and farm trucks, including the selection
of engines and duty cycles.
In addition, EPA decided to incliide a recreational
vehicle (RV) engine in the study because of a concern expressed
by RV owners related to potential engine damage while operating
these engines on low-lead or unleaded gasoline. EPA developed
a duty cycle to be used on the RV engine, after discussions
with consultants and original-equipment manufacturers.
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Engine testing was performed by the National Institute
for Petroleum and Energy Research (NIPER), an independent
research laboratory located at Bartlesville, Oklahoma. (See
Appendix 6 for information on how to obtain a copy of their
report.) Technical advice and oversight were provided by two
consultants, Dr. Louis I. Leviticus of the Nebraska Tractor
Testing Laboratory, Lincoln, Nebraska and Dr. Ralph Fleming
of Energy, Fuels and Engine Consulting Services, Accokeek,
Maryland. The consultants commented on the original program
design, visited the test facility on several occasions and
consulted on major program decisions throughout the study.
Their evaluation of the test program is in Appendix 2.
B. Farm Engine-Use Survey
The second area of this study was a survey of the number
and use of selected gasoline-powered farm equipment (tractors,
combines and trucks). Questions were added to a Farm Labor
Survey conducted in July 1986 by the National Agricultural
Statistics Service, USDA. (See Appendix 5 for a copy of the
survey form and see Appendix 6 for information on how to obtain
a copy of the manual that accompanied the questionnaire.)
Survey results were related to the results of the dynamometer
tests in order to characterize the degree of risk encountered
by farm equipment. Highlights of that analysis are included
in this report. More extensive analysis of the data may
reveal additional information about the use of these engines.
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C. Cylinder Head Survey
Valve seat recession is affected by the type and hard-
ness of the material used in valve seats. A field survey of
cylinder heads was performed to determine what material
(cast iron, soft steel, hard steel or stellite) is in the
exhaust valve seats of tractors. Due to overhauls, engines
may no longer have valve seats meeting original equipment
specificat ions.
The survey, conducted by the Radian Corporation,
Sacramento, California, involved sending an engineer to test
cylinder heads removed by eight tractor dismantling and
salvage firms located throughout the United States. (See
Appendix 6 for additional information on how to obtain a copy
of the protocol and quality assurance plan for this survey.)
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III. Agricultural Machinery Testing on Engine Dynamometers
A. Test Design
Lead combustion products serve as solid lubricants for
some parts of the engine--primarily the exhaust valve seats.
Engines designed for leaded gasoline typically have a valve
seat geometry designed to prevent excessive accumulation o£
lead compounds. They may also use valve rotators for this
purpose. Valve seat wear appears to be related primarily
to engine speed and load.
A tractor duty cycle was designed to reflect a full range
of tractor use conditions. The duty cycle had two parts.
The first part consisted of 144 hours (16 hours/day) at
governed engine speed and loads varying from no load to full
power. This cycle was adopted from the cycle used by the
Nebraska Tractor Testing Laboratory (SAE JVOS).^/ The
second part consisted of a 56-hour continuous test at governed
engine speed and 75% of maximum available power. This segment
represents the maximum continuous load that is likely to be
placed on these engines, such as pumping irrigation viator.
The combine engine was tested using the same duty cycle.
(See Appendix 3 for a description of the duty cycles.)
The farm truck engine was operated throughout the 200
hours at varying engine speeds (2000-3600 rpm) and loads
(25% to 85% of maximum power) representing normal conditions
I/This cycle has a long history of use in testing the perfor-
mance of new tractors.
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for farm trucks larger than one-ton capacity. The RV engine
was operated for 144 hours at varying engine speeds (2000-3600
rpm) and loads (45% to 85% of maximum power) followed by a
56-hour hour steady state cycle (100 HP, which is 52% of
maximum power, at 3000 rpm). The farm truck and RV engines
were operated for 16 hours on and 8 hours off throughout the
tests. (See Appendix 3 for a description of the duty cycles.)
Before each test, the cylinder heads were changed and
broken in on the next fuel being tested. Testing was conducted
on leaded (1.2 gplg), unleaded, and low-lead (0.1 gplg) gasoline,
and gasoline containing non-lead additives.£/ The principal
focus of the testing was to record wear of exhaust valve seats.
Valve clearance was set to manufacturers' specifications each
time a measurement was taken. In addition, the contractor
measured intake valve seat recession, valve stem length, valve
guide and stem wear, valve tulip diameter and valve seat angle,
valve spring force and height, and other measures of engine
wear. Engine performance was monitored and emissions tests were
performed on the exhaust gases. After each fuel test, engines
were carefully examined for deposits and other conditions that
may have resulted from the test. Elemental analyses of the
lubricating oils were conducted. Cylinder heads and valve seat
inserts were carefully selected to control the hardness of
exhaust valve seats.
2/Leaded gasoline in this study contains tetraethyl lead,
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Tractor and combine engines usually have solid valve
lifters. A valve adjustment is needed in the engines after
about every 15 thousandths of an inch of wear and new valve
seats are needed after about 125 to 200 thousandths of an inch
of wear. While repeated valve adjustments theoretically make
it possible to continue operating an engine as valve seat
recession occurs, as a practical matter, an engine operator
is likely to burn a valve and, thus, require an overhaul of
the valve assembly before all of the potential adjustments
can be made. This is because valve seat wear gives an operator
few clues to the problem until significant damage occurs.
There is no increase in engine noise and misfiring and loss
of power often are not noticed until after valves or valve
seats have burned. Automotive-type engines usually have
hydraulic valve lifters so regular valve adjustments are not
needed. New valve seats are needed in these engines after
about 75 thousandths of an inch of valve seat wear. New
valve seats may be obtained by replacing the cylinder head
or by machining out the valve seats and installing valve
seat inserts.
Proper clearance also must be maintained between valve
stems and valve guides. Worn valve stems and guides result
in increased oil usage and may cause excessive valve and valve
seat wear because the valve does not seat properly. When valve
guide clearance increases by more than 2 thousandths of an inch,
many manufacturers recommend that the valve guides be replaced
or that the valves be replaced by ones with oversize stems.
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See Appendix 6 for information on how to obtain a copy of
the statement of work used in the study and a detailed descrip-
tion of the engine tests, including fuel and oil specifications,
engine rebuilding procedures, recession measurement guidelines,
and other test parameters which NIPER was required to follow.
B. Engines Tested
The five farm equipment engines initially selected by
USDA were: John Deere "B", Farmall "H" and International
Harvester 240 tractors, John Deere 303 cubic inch displacement
(CID) combine engine, and a pre-1974 General Motors 292 CID
(GM 292) truck engine. The engines, described in Appendix 4,
represent a broad range of engine sizes and characteristics.
EPA selected the pre-1984 General Motors 454 CID V-8 engine
(GM 454) to represent engines used in RVs.
Plans called for purchase of a duplicate of the engine
that experienced the most valve seat recession on unleaded
gasoline, in order to focus more attention on tests of this
engine. The GM 292 truck engine proved most vulnerable and
a duplicate was purchased. At the request of the USDA and
the American Farm Bureau Federation, a Ford 8N tractor engine
also was procured for the study after it was learned that
one of the other tractor engines selected did not need to be
tested on low-lead gasoline and non-lead additives. Manufac-
turers' specifications for the John Deere "B", International
240, John Deere 303, and GM 292 engines called for ordinary
cast iron cylinder heads without valve seat inserts. Hardness
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-11-
of these valve seats typically ranges from 9 to 25 on the
Rockwell C scale._3/ The Farmall "H" was originally equipped
with "gray iron" valve seat inserts (Rockwell C scale values
of 26-36); the Ford 8N was originally equipped with harder
exhaust valve seat inserts (Rockwell C scale 39-43); and the
General Motors 454 CID engine was originally equipped with
induction-hardened cast iron valve seats (no inserts) with a
Rockwell C scale hardness of: about 55 specified by the manu-
facturer.^/ The General Motors 454 and 292 engines are
currently being manufactured with induction-hardened cast
iron valve seats. All engines were tested with valve seats
meeting original equipment specifications except the Farmall
"H" and Ford 8N. Since the latter engines may have been
rebuilt with different valve seat material, they were tested
with ordinary cast iron valve seat inserts (Rockwell C scale
value of 17).
C. Dynamometer Testing Limitations
The dynamometer testing portion of this study has a
number of limitations. First, budget limitations did not
permit testing enough engines to assure statistical reliabil-
ity. Only one or at most two engines of any given type
could be tested. Second, dynamometer tests typically show
3/Lower numbers indicate softer materials.
4/Hardness of induction-hardened cast iron valve seats typically
ranges from 40 to 60 on the Rockwell C scale.
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raore wear than is found during actual in-use operation of
engines. Every attempt was made to make the tests represen-
tative of actual in-use conditions, but this was difficult
because data on how the engines are used did not exist.
Third, because of time and cost restrictions, valve design
factors which could affect valve seat wear, such as the
presence of valve rotators, were not examined fully. Finally,
unforseen engine characteristics such as air/fuel ratios and
mechanical problems, which appear to have an effect on valve
seat wear rates, were not controlled in the study design.
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IV. Results of Dynamometer Testing
A. Tests of Leaded Gasoline (1.2 gplg)
Baseline tests were run on the six original engines
using gasoline containing 1.2 grams per leaded gallon (gplg).
The duplicate truck engine (GM 292-B) and the additional
tractor engine (Ford 8N) were not tested on gasoline containing
1.2 gplg because none of the original engines showed appreciable
wear with this fuel.
Table 1 summarizes the maximum rates of valve seat
recession (in thousandths of an inch per 100 hours) found
while operating the engines on leaded, low-lead, and unleaded
gasoline. Except for the GM 454 engine, essentially no valve
seat recession was found and no unusual wear occurred on
other engine components when leaded gasoline was used. It
should be noted that the GM 292-A exhaust valve guide diameter
increased by 1.8 thousandths of an inch and that the International
Harvester 240 intake valve guide diameter increased by 14.3
thousandths of an inch (probably due to an oil line blockage
that was corrected early in the test) which are substantially
more than were observed in the other engines. Exhaust valve
seat recession is not a problem with gasoline containing 1.2
grams per leaded gallon.
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Table 1--Maximum exhaust valve seat recession rates*--continued
4/ Recession may have heen influenced by improper alignment
of rocker arm assembly. _5/ Operated 244 hours. j3/ Operated
300 hours. _7/ Results are for two tests. During the first
test (the larger recession rate), the cylinder head gasket
failed and may have generated additional heat which contributed
to the recession. ^/ Engine could complete only 71 of the
scheduled 200 hours due to recession. _9/ Engine was run
without the 3600 rpm part of the duty cycle. 1O/ Engine was
stopped after 88 hours of operation due to recession.
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B. Tests of Unleaded Gasoline
All engines procured for this test program were evaluated
on unleaded gasoline. Recession data are summarized in
Table 1 and Appendix 1, Figures 1-13. Principal findings
are as follows.
1. The John Deere "B" tractor engine was tested twice
on unleaded gasoline (Appendix t, Figures T and 2). The
first test found that one cylinder had 11 thousandths of an
inch of recession after 200 hours of operation, all of
which occurred during the steady state portion of the test.
Examination of the engine after the test showed that the
rocker arm was not striking the valve stem tip properly and
it was believed that recession was due to this mechanical
problem instead of the fuel. This may have caused valve
guide diameter wear to increase from 1.0 thousandths of inch
for the leaded fuel test to 3.2 thousandths of an inch during
the first unleaded test. After properly aligning the rocker
assembly, the unleaded test was repeated with a new cylinder
head. Both exhaust valve seats experienced some recession
after 80 hours, but no additional recession through 200
hours. The test was continued on the intermittent portion
of the duty cycle for 100 more hours and no additional reces-
sion occurred. Valve guide diameter wear was consistent
with the rate observed for leaded gasoline. Valve stem
wear increased from 0.2 thousandths of an inch for leaded gas-
oline to 0.8 thousands of an inch for unleaded gasoline. No
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other unusual wear was observed. The John Deere "B" tractor
engine may experience a small amount of valve seat recession
but should not have problems operating on unleaded gasoline.
2. The Farmall "H" tractor engine did not experience
valve seat recession or any other unusual wear while operating
on unleaded gasoline and was not tested any further (Appendix 1,
Figure 3).
3. The John Deere 303 CID combine engine experienced
substantial valve seat recession while operating on unleaded
gasoline (Appendix 1, Figure 4). At 144 hours, all cylinders
showed recession ranging from 10 to 24 thousandths of an
inch. After the steady state portion of the test, total
recession ranged from 41 to 63 thousandths of an inch.
Valve guide wear increased from a maximum of 0.2 thousandths
of an inch on leaded fuel to 1 .5 thousandths of an inch on
unleaded fuel.
4. The International Harvester 240 tractor engine was
tested three times on unleaded gasoline. The first test
showed no valve seat recession (Appendix 1, Figure 5). We
subsequently found that the cylinder head used was among the
hardest of the heads purchased for the tests. It was decided
to test the engine a second time using a cylinder head at
the softer end of the hardness range of heads available.
Substantial valve seat recession (43-49 thousandths of an
inch) occurred on two of the valve seats (Appendix 1, Figure 6).
About one-half of the recession occurred during the 56-hour
steady state portion of the test cycle.
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Further investigation of the cy]inder heads after the
tests were completed revealed that the hardness of the metal
in the seat area was essentially the same for hoth heads.
Differences in wear in the International 240, therefore, were
not due to differences in hardness of the valve seats.
Evaluation of the data revealed that the air/fuel ratio was
much higher during the test that exhibited valve seat recession
even though the engine was set to the manufacturer's specifica-
tions (Tahle 2). The higher air/fuel ratio may have contributed
to the valve seat recession since a leaner mixture would
cause higher exhaust temperatures. After the test was completed,
the carburetor was cleaned and the air/fuel ratio returned
to its original level.
A third unleaded test was performed on the engine using
exhaust valve seat inserts. The inserts were of about the
same hardness as the valve seats in the first two unleaded
tests on this engine. Appendix 1, Figure 7 shows that no reces-
sion occurred during the first 80 hours but then occurred very
rapidly. After 144 hours of variable loads, recession ranged
from 16 to 47 thousandths of an inch and then rose to 63 to 94
thousandths of an inch during the final 56 hours of steady
state operation. The air-fuel ratio did not rise during this
test. This test suggests that engines with valve seat inserts
are more susceptible to recession than engines without inserts
when the valve seats are of equal hardness.
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Table 2--Average emissions and air-fuel ratios by engine
and test fuel
Engine and fuel
00 1/
HC 2/
NOx 3/
Air-
fuel
ratio
Percent ppm gpm
John Deere B
1.2 gplg 5.3 3,303 679
Unleaded
Run 1 9.3 3,202 202
Run 2 6.0 3,605 847
Farmall H
1.2 gplg 5.1 3,544 1,008
Unleaded 4.2 2,187 1,116
International 240
1.2 gplg 5.1 3,133 817
Unleaded
Run 1 5.7 2,358 925
Run 2 2.1 1,338 1,380
Inserts 4.6 2,022 NA
0.1 gplg
No inserts 6.3 2,606 868
Inserts 5.6 2,104 NA
John Deere 303 CID
1.2 gplg 4.9 3,610 1,212
Unleaded 4.6 1,951 1,305
0.1 gplg 6.3 2,612 738
DuPont additive 4/ . . 5.2 2,033 NA
Standard "PowerShield"
additive _5/ 7.3 2,482 NA
Ford 8N
Unleaded 5.5 2,933 NA
GM 454 CID
1.2 gplg 2.0 1,726 1,950
Unleaded
No inserts 2.5 930 1,802
Steel inserts ... 3.4 813 NA
0.1 gplg 2.5 1,090 1,868
Standard "PowerShield"
additive 5/ . . . . 3.0 891 NA
13.0
10.9
12.2
13.0
13.4
12.7
12.5
14.3
12.9
12.3
12.5
12.7
13.0
12.2
12.7
11.8
12.5
14.0
13.8
13.4
13.9
13.6
Continued--
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Table 2--Average anmissions and air-fuel ratios by engine
and test fuel—continued
Engine and fuel
00 1/
HC 21
NOx 3/
Air-
fuel
ratio
Percent ppm
GM 292 CID, engine A
1.2 gplg 3.8 2,356
Unleaded 4.3 1 ,006
0.1 gplg
Run 1 3.0 1,597
Run 2 3.9 1,182
aiPont additive 4/ 3.8 1,054
Standard "PowerShield"
additive 5_/ 2.7 1,205
GM 292 CID, engine B
Unleaded
IHCI 6/ 3.9 1,436
Lighter load 7/ ... 3.9 1,222
0.1 gplg 5.2 1,416
Concentrated "PowerShield"
additive 8/ 4.9 2,865
1,339
1,119
1,696
NA
NA
1,924
1,398
NA
NA
NA
13.4
13.1
13.7
13.2
13.3
13.6
13.1
13.2
12.7
12.7
J_/ Carbon monoxide.
2/ Hydrocarbons.
7/ Nitrogen oxides.
4_/ 200 pounds of additive per 1,000 barrels of gasoline.
5/ 250 pounds of additive per 1,000 barrels of gasoline.
][/ Induction-hardened cast iron exhaust valve seats.
7J Engine was run without the 3,600 rpm part of the duty cycle.
EV 1 ,000 pounds of additive per 1 ,000 barrels of gasoline.
-------
- 21 -
Valve train inspection data show that exhaust valve
guide wear was up to 2.2 thousandths of an inch without
inserts and up to 3.7 thousandths of an inch with inserts
compared to a maximum of 0.9 thousandths of an inch with
leaded fuel and no inserts.
5. Tested with ordinary cast iron valve seat inserts,
the Ford 8N had up to 17 thousandths of an inch of valve seat
recession after 144 hours, and 17 to 29 thousandths of an inch
of recession after 200 hours, a significant amount of wear
(Appendix 1, Figure 8).
Two cylinders may have had ahove-normal valve guide wear
based on comparisons with the leaded fuel tests on the other
engines (the Ford 8N does not have a leaded-fuel baseline test
since none of the original engines tested showed appreciable
wear with this fuel).
6. The GM 292-A CID truck engine, when tested on unleaded
fuel with ordinary cast iron valve seats, experienced the
highest rate of recession (Table 1 and Appendix 1, Figure 9).
In fact, the test had to be terminated after 71 hours due to
fear that the engine would be severely damaged by excessive
valve seat recession. Exhaust valve guide wear increased
but not substantially more than found in the leaded test.
A duplicate engine, GM 292-B, was tested with the harshest
portion of the duty cyclo (3600 rpm) deleted. The wear rate
was reduced by 40 percent, but the test still had to be
terminated after 88 hours due to excessive valve seat recession
-------
- 22 -
(Appendix 1, Figure 10). Subsequently, the GM 292-B engine
was tested with induction-hardened cast iron exhaust valve
seats, and experienced 11 thousandths of an inch of recession
after 200 hours (Appendix 1, Figure 11). However, there was
a greater change in exhaust valve guide diameter (a maximum
of 4 thousandths of an inch versus 1.8 thousandths of an
inch for leaded fuel) during this test. Valve length was
reduced by up to 8 thousandths of an inch compared to increases
of up to 4 thousandths of an inch for leaded fuel.
7. The GM 454 recreational vehicle engine was tested
with induction-hardened cast iron valve seats. All cylinders
showed significant recession, ranging from 14 to 30 thousandths
of an inch after 144 hours. Total recession increased slightly
to a maximum of 34 thousandths of an inch after the steady
state portion of the test (Appendix 1, Figure 12). The
induction hardening process for the GM 454 affects the valve
seats to a depth of about 50 thousandths of an inch. Rapid
wear would be expected after the induction-hardened portion
of the valve seat is worn away. Exhaust valve guide wear
increased from a maximum of 1 thousandths of an inch using
leaded fuel to 4.6 thousandths of an inch while operating
on unleaded fuel.
A second test on unleaded fuel was conducted using soft
steel "XB" valve seat inserts (Rockwell C scale value of 42)
designed for moderate-duty use. This test also showed valve
seat recession but it was much less; 17 thousandths of an inch
-------
- 23 -
after 144 hours with little recession during the final steady
state portion of the test (Appendix 1, Figure 13). Maximum
exhaust valve guide wear of 1.7 thousandths of an inch occurred
compared to 1 thousandths of an inch on leaded fuel.
8. Summary of Results on Unleaded Gasoline.
Engines operated at low speeds (e.g., John Deere B,
rated at 1250 rpm; and Farmall H, rated at 1650 rpm) should
have little or no problem operating on unleaded gasoline,
regardless of the type of valve seat material. Engines
which operate at medium rpm (e.g., International 240 and
Ford 8N rated at 2000 rpm) are likely to experience significant
valve seat recession unless they are used only for light-duty
tasks or have hard steel valve seat inserts. Engines operated
under heavy-duty steady state conditions may experience 2-4
times more recession than engines operated under a wider range
of load conditions.
Farm equipment engines operating at higher speeds (e.g.,
John Deere 303 CID, rated at 2500 rpm) which have ordinary
cast iron valve seats probably will experience considerable
valve seat recession. Based on the tests of the GM 292 and
GM 454 CID engines, we concluded that automotive-type engines
of the type tested, when operated under conditions represented
by the duty cycles used in these tests, are extremely suscept-
ible to valve seat recession when they have ordinary cast
iron valve seats. Furthermore, the tests on the GM 454
showed that engines could experience considerable recession
-------
- 24 -
even if they are equipped with induction-hardened cast iron
valve seats which are still being installed in new vehicles.
Based on tests of the GM 454, soft steel inserts also are
vulnerable with unleaded fuel although wear rates appear to
be lower than for induction-hardened cast iron seats. Unleaded
gasoline also increases valve guide wear and may increase
valve stem wear.
Factors other than the lead content of fuel also affect
valve seat recession, probably because of heat differences.
Higher air/fuel ratios appear to increase valve seat recession.
Engines with valve seat inserts appear to be more susceptible
to valve seat recession than engines with equally hard integral
cylinder head seats. The use of valve rotators also may
increase recession.
C. Tests of Low-lead Gasoline (0.1 gplg)
Four of the original six engines showed significant
recession on unleaded gasoline and, therefore, were tested
on gasoline containing 0.1 gplg. The John Deere 303, the
International 240 (with and without valve seat inserts) and
the GM 454 engines all operated satisfactorily on 0.1 gplg
(Table 1 and Appendix 1, Figures 14, 15, 16, and 17).
Other parameters measured showed no changes for the
International 240. Compared to leaded fuel, maximum valve
guide wear increased from 1.0 thousandths of an inch to 2.0
thousandths of an inch in the GM 454 and from 0.2 thousandths
on an inch to 1.2 thousandths of an inch in the John Deere 303.
-------
- 25 -
The GM 292-A experienced significant recession after
91 hours (Appendix 1, Figure 18). Since the head gasket failed
at about that time, and may have contributed to the valve
seat recession, it was decided to retest the GM 292-A engine
and the duplicate GM 292-B, engine on this fuel.£/ One of
the engines showed no increase in wear compared to the leaded
test. The other engine showed slightly more recession in
one cylinder. Overall, little recession occurred in these
subsequent tests (Appendix 1, Figures 19 and 20). Under
good operating conditions, most farm engines probably will
experience little or no valve seat wear using 0.1 gplg gasoline.
However, 0.1 gplg appears to be at or near the minimum
level needed by most of these engines when they are properly
maintained and operated under conditions similar to the duty
cycles tested, unless other forms of valve seat protection
are used (such as non-lead additives or more wear-resistant
seat materials).
The technical specialists who worked on this study
believe that excessive heat may contribute significantly to
valve seat recession. The head gasket failure and differences
in air/fuel ratios observed in this study are two of many
£/The exact time that the gasket failure started to
occur is not known because it did not cause an abrupt change
in the engine's behavior or in the performance measures being
monitored, such as power, engine temperature and emissions.
One of the consultants on the project (Dr. Ralph Fleming)
examined the test data and engine characteristics to determine
if the gasket failure caused the recession, and reported that
a conclusive determination could not be made.
-------
- 26 -
factors that could cause excessive heat that may not be
detected by operators in everyday engine operations. An
improperly maintained engine might experience excessive
valve seat recession even when high concentrations of lead
are in the gasoline, but good engine maintenance is especially
important when using gasoline containing only 0.1 gplg or less
of lead.
D. Tests of Non-lead Additives^/
Two proprietary additives were evaluated in the test
program.jV An additive manufactured by Lubrizol Corporation
(Lubrizol) was tested on the John Deere 303, GM 454 and GM
292 A and B engines. The second additive, produced by E.I.
duPont de Nemours and Company (DuPont), was evaluated on the
GM 292-A and the John Deere 303 engines.
Table 3 and Appendix 1, Figures 21-25, summarize the
rates of exhaust valve seat recession found while operating
the engines on the Lubrizol and DuPont additives.
1. Test Results Using the Lubrizol Additive
Three formulations of the Lubrizol additive were tested.
^/Products containing tetraethyl lead to be added by the
consumers were not evaluated because we would expect the same
results as with the leaded-fuel tests that were conducted.
^/Additives were selected for testing in this program if
the manufacturers indicated to EPA a desire to have their pro-
ducts tested and they provided data to EPA which showed that
their products had the potential for reducing valve seat
recession when used with unleaded gasoline.
-------
-27-
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The first, a modified version of a product Lubrizol sells
under the trade name "PowerShield" had little effect on valve
seat recession. Lubrizol, subsequently, notified NIPER that
the product had not been properly formulated and asked that
"PowerShield" be tested. "PowerShield" was tested at the manu-
facturer's recommended concentration of 250 pounds per 1,000
barrels of gasoline* For the GM 454, recession was about
comparable to that found using 1.2 gplg and 0.1 gplg. However,
compared to unleaded gasoline, "PowerShield" slightly reduced
but did not stop wear in the other two engines tested
(John Deere 303 and GM 292-A) (Table 3 and Appendix 1, Figures
21, 22, and 23). Valve guide wear was above normal with
"PowerShield" (based on the test using 1 ..2 gplg gasoline) in
the John Deere 303 (3.3 thousandths of an inch compared to
0.2 thousandths of an inch with leaded).
"PowerShield" was tested in one engine (GM 292-B) at a
concentration of 1,000 pounds of additive per 1,000 barrels
of gasoline (four times the level normally recommended for
the product). Valve seat recession was stopped (Appendix 1,
Figure 24). Valve stem wear was slightly greater than was
observed for both leaded and unleaded gasolines.
The "PowerShield" additive caused deposits to form in
the combustion chamber of the engines. Engine deposits
increased when the "PowerShield" concentration was quadrupled.
Combustion chamber deposits can increase an engine's octane
requirement, but it is not clear from this testing whether
-------
- 29 -
the deposits seen would significantly alter octane requirements
or have any other effects on the engines.
"PowerShield" at the 250 pounds of additive per 1,000
y
barrels of gasoline also caused oily black deposits to form
on intake runners, but the implications, if any, are not
known. This occurred in both the GM 292-A and John Deero 303
engines and to a lesser extent in the GM 454.
Examination of lubricating oils revealed substantially
higher levels of sodium in the oil after running the engines
on "PowerShield." Two of the engines also had elevated
levels of phosphorus and the engine that ran on "PowerShield"
at 1,000 pounds of additive per 1,000 barrels of gasoline had
much larger quantities of sulfur in the oil.
2. Test Results Using the DuPont Additive
Two engines (John Deere 303 and GM 292-A) were tested on
the DuPont additive at about twice the concentration normally
recommended by the manufacturer. The test on the John Deere
303 was terminated after only 48 hours due to a problem with
the engine's cooling system. At that point, essentially no
valve seat recession was occurring. However, 48 hours was
not long enough to yield meaningful results.
The DuPont additive reduced valve seat recession in the
GM 292-A engine, although, at 22 thousandths of: an inch per
100 hours, wear was st 11 excessive (Table 3, and Appendix 1,
Figure 25). The additive caused deposits to form in the
ongine. A large amount of hard, sticky deposits was found on
-------
-30-
th e intake valves. One intake valve was unable to close
completely and was beginning to burn. Inside the combustion
chamber, a glaze deposit had formed on valve surfaces. The
full implications of these deposits, including the potential
for eliminating them, are not known.
Examination of the lubricating oils revealed substantially
higher levels of phosphorus after running engines on the
DuPont additive.
3. Summary of Additive Testing
The DuPont additive, at about twice the concentraton
normally recommended by the manufacturer, provided some degree
of protection against valve seat recession. At the manufac-
turers recommended concentration, Lubrizol's "PowerShield"
reduced recession. At four times the concentration normally
recommended by the manufacturer, Lubrizol's "PowerShield"
stopped recession in the one engine tested. Both additives
produced engine deposits which raised unanswered questions.
The DuPont additive increased the amount of phosphorus in the
lubricating oil. "PowerShield" also increased the amount
of sodium, sulfur, and phosphorus found in the lubricating
oils. Nevertheless, although further product development
work is essential, the additives may have potential as sub-
stitutes for lead.
-------
-31-
V. Results of the Farm Engine-Use Survey and Cylinder Head Survey
The National Agricultural Statistics Service, USDA
conducted a survey of farmers to learn how many gasoline-
powered tractors, combines, and large trucks are in use on
farms and how much they are used. The survey was conducted
in July 1986. The questionnaire is in Appendix 5. (See
Appendix 6 for information on how to obtain a copy of the
manual that accompanied the questionnaire.)
At that time, farmers operated a total of 4.4 million
tractors, of which 1.8 million were gasoline powered and 2.6
million were diesel powered. The gasoline-powered tractors,
which average 26 years of age, were used an average of 250
hours in 1985. The amount of use varies with the size of
the tractor (Table 4). Further, tractors with low annual
hours of operation tend to see more light duty use (Table 5)
than tractors that are used more.
About 42 percent of gasoline-powered farm tractors are
used exclusively in light duty tasks and, therefore, have
little risk of valve seat recession if operated on unleaded
gasoline. The other 58 percent of tractors see some medium
and heavy uses which potentially make them vulnerable to
excessive valve seat wear if fueled with unleaded gasoline,
unless they are low-rpm engines, have hardened exhaust valve
seats, or are protected by a fuel additive.
-------
-32-
Table 4--Distribution of gasoline-powered
tractors by size and hours of use, 1985
Annual
hours of use
20-49
50-99
1 00-149
150-249
250-499
500-749
750-1499
1 ,500 or more
All tractors
Number of tractors
213,784
324,146
321 ,520
350,372
303,857
141 ,992
84,884
33,160
1 ,773,715
Average horsepower
31
34
38
43
46
49
49
54
40
-------
-33-
Table 5--Annual use of gasoline-powered tractors, 1985
Annual
hours
of use
20-49
50-99
100-149
150-249
250-499
500-749
750-1 ,499
1 ,500 or more
All tractors
Percentage distribution of use
Irrigation
pumping
0.35
0.05
0.44
0.42
0.17
0.41
0.27
0.16
0.29
Hard
use
8.61
9.15
9.99
12.26
14.37
16.80
18.72
23.00
12.08
Medium
use
25.48
30.08
33.92
34.29
36.77
40.45
43.22
43.54
33.91
Light
use
65.55
60.71
55.64
53.03
48.68
42.34
37.79
33.31
53.72
-------
-34-
Farmers operate 271,000 gasoline-powered combines that
average 19 years of age. On average, each combine harvested
220 acres of grain in 1985. Combines, like tractors, see a
skewed use distribution (Table 6). All combine engines
receive hard use and are likely to experience excessive
valve seat recession if they have cast iron valve seats and
are operated on unleaded gasoline.
About 750,000 gasoline-powered trucks larger than 1-ton
capacity are used on tarms. They average 19 years of age
and were driven an average of 3,800 miles in 1985. Over
half of the trucks were driven less than 2,000 miles (Table 7).
Trucks receive a range of light to hard uses. Data are not
available that would more precisely characterize this use
although, on average, it is thought to be represented by
the duty cycle specified for the tests conducted by NIPER.
The Radian Corporation conducted a survey of tractor
dismantling operations to determine the type of material in
tractors' valve seats. (See Appendix 6 for information on how
to obtain a copy of the protocol and quality assurance plan
for this survey.) An eddy-current test *ias used to identify
stellite valve seats and steel/cast iron seats. A chemical
test (for the presence of chromium) was then used to distin-
guish between valve seats made of steel and cast iron. Data
were obtained from eight establishments located throughout
the United States. This survey is subject to large sampling
and measurement errors and the data have not been fully
-------
-35-
Table 6--Distribution of number of gasoline-powered
combines by number of acres harvested, 1985
Number of acres harvested
Number of combines
1-99
100-199
200-299
300-399
400-499
500-999
1,000 or more
All combines
101,641
69,159
32,418
24,446
13,793
22,594
6,294
270,345
-------
Table 7--Annual miles of farm trucks
larger than 1 ton rated capacity, 1985
Total annual
miles driven
Number of trucks
0-1,000
1,001-2,000
2,001-3,000
3,001-4,000
4,001-5,000
5,001-10,000
10,001-20,000
20,001 or more
All trucks
254,805
145,783
81,896
42,568
74,053
96,361
32,341
5,955
733,762
-------
-37-
examined at this time. A preliminary analysis suggests that
33 percent of all gasoline-powered tractors may have hard
valve seat inserts. These would not be vulnerable to valve
seat recession with unleaded gasoline. The remaining 67
percent of the tractors have cast iron inserts or have seats
that were machined into the cast iron heads. These tractors
are potentially vulnerable to valve seat recession with
unleaded fuel if the engines are operated under medium-duty
and/or heavy-duty conditions.
While hundreds of thousands gasoline-powered engines on
tractors, combines, trucks and other large farm equipment
face no risk of damage if fueled with unleaded gasoline,
hundreds of thousands of others need lead or an effective
substitute if they are to continue in their present uses
without needing an engine overhaul.
-------
-38-
Appendix 1
Exhaust Valve Seat Recession by Cylinder
-------
-39-
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Appendix 2
Consultants Evaluations of
Engine Testing Performed by NIPER
-------
-65-
Ralph D. Fleming
Consultant
17506 Clinton Driye
Accokeek, Maryland 2O6O7
(301) 283-6520
Energy. Fuels and Engine Consulting Services
March 2, 1987
Mr. Richard G. Kozlowski
Director, Field Operations and Support Division
EN-397F
U. S. Environmental Protection Agency
Washington, DC 20460
Dear Mr. Kozlowski:
The purpose of this letter is to provide comments on the testing program
involving agricultural engines that was conducted by the National Institute for
Petroleum and Energy Research (NIPER) at Bartlesville, Oklahoma. The final report
resulting from that study is entitled "Effect of Low Levels of Lead and Alternative
Additives to Lead on Engines Designed to Operate on Leaded Gasoline". In order to put
my comments into perspective, some background information on the overall study will
be given.
Background
During the latter part of Calendar Year 1985, a proposed test plan was developed
by the Environmental Protection Agency (EPA) in cooperation with the U. S.
Department of Agriculture (USDA). That test plan was reviewed and commented on in
December 1985 by representatives from various engine manufacturers, universities,
government agencies, organizations representing the farmers and other interested
parties. An EPA/USDA meeting was held in January 1986 with members of the various
reviewing groups to discuss the development of the testing program. The contractor
was under contract to do the work by early summer of 1986 and actual engine testing
was begun in June 1986. The draft final report was delivered to EPA for review in
January 1987.
Because of a variety of different equipment configurations ranging from two to
eight cylinder engines, laboratory modifications were necessary to accommodate the
various engines. Some engines required pressurized cooling systems, while others
operated at atmospheric pressure. Some older engines used in the study had carburetor
systems that were inherent y poor in their ability to control air—fuel ratios.
Procedures for determining valve seat hardness and recession during the accumulations
had to be developed by the contractor.
-------
-66-
Severai factors unrelated to the fuels being tested, resulted in setbacks of the
experimental schedule. They included: failures of dynamometer equipment-
mechanical failures of engines; and an unusual amount of rainfall in the vicinity of the
contractor site which flooded the laboratory-
Performance of Contractor
The contractor has done an excellent job in conducting the testing program and
executing th« various tasks on a reasonable time schedule, considering the short lead
time for setting up the experiments and the many setbacks that were beyond the
contractor's control. The quality of the data is as good as could be expected,
considering the limitations on the budget and the number of eng>nes available for
testing. The methods developed for determining valve seat hardness and recession
dunng the accumulation of hours were adequate for the purposes of the study. The
valve seat recession measurements taken during the accumulation of hours were
backed-up by bench inspections of the cylinder heads. The bench measurements were
mads beforp the start of the accumulation of hours on the engines and after the
completion of each test by an independent certified automotive mechanic. This was an
excellent method tor confirming the accuracy of valve seat recession measurements
because the two separate measurements were made totally independent from each
other.
The testing program was well conceived with a representative cross section of
engine types being incorporated into the testing. The chosen engine duty cycles were
good in that they served to show valve seat recession as a function of fuel type for some
engines, while other engines showed no valve seat recession with any of the fuels. !n
general, the contractor performed well in executing the experimental testing in a
timely fashion and produced a technical report that provides useful data on the effect of
gasoline lead levels and alternative additives to lead on valve seat recession in engines
that were originally designed for leaded gasoline. However, at no fault of the
contractor, EPA or USDA (because of budget constraints), it would have been helpful to
have had more engines in the testing program. This aspect will be discussed further in
the following section.
Adequacy of the Test Data
The data from the program are adequate for the purposes of the study with the
exception of two areas. One area relates to the question of whether or not lead at 0.10
gram per gallon in gasoline is adequate to prevent valve seat recession in all of the
engines tested. The Ford 8N engine was not tested on 0.10 gram per gallon leaded
gasoline, therefore, no data are available to determine if 0.10 gram per gallon leaded
gasoline would prevent valve seat recession in this engine. The GM 292 engine showed
significant valve seat recession in one cylinder with 0.10 gram per gallon leaded
gasoline. Because a head gasket failure occurred mid-way through the accumulation of
hours on this first test, the engine was rebuilt and retested and 10 thousands of an inch
recession was noted for one valve seat. A duplicate GM 292 engjne was tested later in
the program with no observed valve seat recession. Although a head gasket failure
occurred In the first test, the engine was repaired at 120 hours and the test was
continued to 200 hours. Valve seat recession continued after the head gasket
replacement at 120 hours. Although the rate of valve seat recession was lower after
-------
-67-
the head gasket replacement than that just prior to the head gasket failure, there
appears to be no basis for throwing out this test result. The overall results from the
GM 292 engine tests for 0.10 gram per gallon leaded gasoline are mixed. Further
engine testing is required to determine whether or not 0.10 gram per gallon leaded
gasoline will provide adequate protection against valve seat recession in the GM 292
engine.
The second area which needs further study is alternative additives. One additive
(additive "D") tested in the current program showed good results when blended at a
concentration of 1,000 pounds of additive to 1,000 barrels of gasoline. However, the
lubricating oil wear metals analyses for the additive "D" test showed increased
concentrations of iron, chrome, sodium and molybdenum when compared to other fuel
tests with the same GM 292 engine. These results indicate the need for longer term
engine durability testing with the additive to determine any adverse effects on the
engine such as deposit formation in the engine or increased wear. Since the additive
contains sodium and possibly other metallic elements, an assessment should be made to
determine if the use of the additive might result in potential degradation of air quality.
Recommendations for Future Work
Should additional engine testing be considered in the future, I suggest that
additional studies be done on alternative additives as a method for preventing valve seat
recession. In addition to identifying additives that successfully prevent valve seat
recession, once an additive has been shown to be effective, further work would be
needed to determine any detrimental effects the additives might have on the engine.
If further testing is done, I recommend that a larger number of engines be tested
to account for engine-to-engine, test-to-test, and day-to-day variability. In
addition, changes in uncontrolled engine variables such as air-fuel ratio may influence
valve seat recession. The experimental tests just completed indicate that a larger
number of engines is required to give conclusive results.
An example illustrating the need for a larger number of engines is the
International Harvester 240 engine used in the current study. The first test with
unleaded gasoline showed no valve seat recession. A repeat test with a slightly softer
cylinder head showed exhaust valve seat recession in two cylinders. At this point, one
might conclude that the softer cylinder head was responsible for the valve seat
recession in the repeat test. However, subsequent inspections to determine the
hardness of the cylinder head material near the individual valve seats indicated that the
observed valve seat recession in the repeat test probably was not due to differences in
hardness between the two cylinder heads. It was also noted that the engine's air-fuel
ratio (uncontrolled variable) was significantly leaner for the repeat test which could
have contributed to increased valve recession. A third test was run on this engine using
unleaded gasoline with cast iron valve seat inserts which resulted in exhaust valve seat
recession in all of the cylinders. In the third test, the average daily air—fuel ratio was
similar to the first test. The variation in test results for a given system suggests the
need for replicate testing for each engine/fuel combination in the testing program.
It is recognized that it is impractical to run every engine type in the overall
population. However, once a given set of engines is selected for testing, replicate
testing of each engine setup and fuel is highly desirable. In many cases, it is impractical
to run enough engines and tests to provide statistically significant results. However, a
-------
-68-
compromise situation may be appropriate for providing a basis for good engineering
judgments. For a test program such as the one just completed, three tests is the
minimum number of replicates which would give reasonable confidence in the data.
This could be done in two different ways. One way would be to repeat the same test
three times on the same engine. The second way would be to run three identical engines
simultaneously. Should further testing be considered in the future, I strongly
recommend that replicate testing be done to increase confidence in the resulting data.
One way to reduce test-to-test and day-to-day variability, and possibly reduce
the number of engine tests required to provide conclusive results, is to control air-fuel
ratio. First, one would have to determine the normal operating air-fuel ratio for each
operating mode and the variation of air-fuel ratio within each mode for each given
engine. Then the air—fuel ratio would be controlled (by means of a special laboratory
apparatus) at its "average" value throughout the accumulation of hours on each test.
The air-fuel ratio would be controlled at a different value for each operating mode
corresponding to the normal air—fuel ratio characteristics of the engine.
Since most of the engines tested showed a problem with valve seat recession on
unleaded fuel an assessment should be made to compare the relative cost and
practicality of retrofitting cylinder heads with hardened valve seats to using
alternative additives or using D.10 gram per gallon gasoline. This assessment should
take into account the total number of engines in the field, the number of engines that
have potential for a valve seat recession problem, etc.
Summary
In summary, the contractor has done an excellent job in conducting the
experimental work and completing the project in a reasonable time frame. The data
from this program are of significant value and should be published in a form such that
anyone in the public domain can obtain a copy of the report. In addition, the contractor
should be encouraged to publish the results of the study in an engineering society
technical paper. Should any future testing be contemplated, I recommend that
additional work be done on alternative additives to lead. An assessment should be done
to determine the cost and practicality of retrofitting cylinder heads with hardened
valve seats. Also, replicate engine tests should be considered to better account for
test-to-test variability.
Should there be any questions about these comments, please do not hesitate to give me
a call.
Sincerely,
Ralp'h D.Fleming '
Consultant
CC:
Jerry Allsup, NIPtR
John Garbak, EPA
Gerald Grinnell, USDA
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-69-
REPORT
Assess.ment of the testing p_ro.gram conducted by NJ,PER on selected
gasp]. ine engines...
Louis I. Leviticus
Nebraska Tractor Testing Laboratory.
March 25, 1987.
1. 1 want to compliment NIPER, and in particular Mr. All sup and
his staff, for a job well done under severe time constraints. The
work was carried out with competence and integrity. The only
criticism I have is the fact that the oil analysis was not
carried out exactly as in the original plan of work.
2. One of the great limitations of this project has been the fact
that not enough engines of each type could be evaluated. It. is
guite clear from the hardness measurements that considerable
variation exists between heads. This variation may be the result
of manufacturing processes or may be due to different sources for
the heads or inserts used. Hence, tests of the statistical
significance cannot be applied in this study.
3. Although the results obtained may be debatable from a
statistical significance viewpoint, they nevertheless provide a
good insight into the problems encountered when operating an
engine, designed for leaded fuel use, on unleaded fuel and with
addi t i ves.
4. In general, the results tend to show that the combustion
chamber temperature may be a major contributor to the phenomenon
of recession of valve seats below a certain critical hardness
value. Higher combustion chamber temperatures can occur due to a
variety of reasons:
a. High loads.
b. Inadequate cooling (dirty radiator, si i piping belts, blocked
passageways in the engine etc.).
c: . Lean fuel mixtures (High A/F ratio).
d. Ignition problems (Timing, Fouled spark plugs).
e. Carbon or other deposits in the combustion chamber.
5. It cannot be determined with certainty from the data what the
critical seat hardness is. This would seem to depend upon, the
engine characteristics and, possibly, on the way the engine is
used and maintained.
6. Engine speed may not be a factor by i tsel-f-p-bu^-f coupled with
a high load and/or a 'Jean mixture an increase in engine speed may
lead to earlier recession. This is a judgement call. The study
was designed to simulate the operation of engines under normal
conditions. It accomplishes that purpose. However, several
guest ions remain unanswered concerning what exactly causes
recessi on .
-------
-70-
7. The results tend to show that ai 0,1 gplg none of the engines
s u f i e r • e d f r o m e x c: e B s r e c e s s i o n . A d e f i n i t e c o n c:: 11.i s :i c1) n c: a n n o t b t?
reached however since one of the engines did show excessive
recess:! on after head gasket failure. Si nee the test did not
examine the harshest possible operating conditions, one cannot
conclude that 0.1 qp] g will protect. all engines under all
operating conditions.
8. The data from the additive tests, limited as they were, do not
warrant their recommendation,at this stage, as a replacement for
lead. This conclusion is based on the following reasons:*
a. It appears that there is, as yet, uncertainty about the
correct cocentration of some of the additives. I may point
out that. it is possible that different engines might
reguire different concentrations of an additive.
b. The recommended concentrations, for the additives tes-
ted, showed that, the engines were not completely protected
against recession.
c,, An examination of the effect of the additives on emissions
was inconclusive.
d« The oil analysis showed that when additives were used, the
Sodium content usually increased drastically. The sodium is
apparently introduced to the oil through the additive.
Since the formulation of the additives is proprietary the
composition of the compound in which sodium occurs is not
known.
e. The oil and exhaust gas analysis did not include checking
for sulphur compounds. Sulphur in the exhaust qases can
cause damage1 +o the engine and exhaust parts since they are
mixed with Hydrocarbons and water vapor and may form acids;
the sulphur compounds in the 0.1 3 cart cause damage in
certain engines since they attack certain metal compounds,,
It is very difficult to determine which engines would be
affected, since this depends upon;
.» Engine combustion characteristics, which can vary with
engine design and operating conditions.
.„ Different oils contain different additives which may
react differently with sulphur compounds.
.. Metal alloys used in the engine. There are examples of
manufacturers warning the users against certain oils,
c o n t. aim n g a m o 1 y b d e n u m c o m p o u n d , w h i c h release s a
sulphur compound in the oil. This compound then combines
wit h w a t e r to c r • e a t e a n a c id, w h i c h a 11 a c k s c. e r't a i n
alloys used.
f „ The nature of the deposit;;:: found and their long-term
influence on the engine were not determined.
g. The only fuel additive combination, which did not cause re-
cession was tested on one engine only,
9. Re c o m m e n d a t i o n s f o r f u t u r e t e s t .1 n g ,
The additives should be tested and evaluated -further in order to:
a,, Determine the correct concentrat. i on (s> to be used.
b. Investigate whether the concentrations should differ for
different engine makes.
c. Determine the composition of the exhaust gases and their
-------
-71-
influence, i -f any, on the various engine components.
d. Determine the influence on the composition of engine oils
and the influence of- i he compounds on the oil quality and
on alloys used in various engines.
LouiB I.
Nebraska
Testinq Lab
-------
-72-
Appendix 3
Duty Cycles Used in Engine Tests
Duty cycles were developed to represent conditions
normally encountered by farm tractors, combines and large
trucks, and by recreational vehicles. Each engine was operated
on its specified duty cycle until 200 hours were accumulated
on each test fuel.
Tractors and Combines
The duty cycle for tractor and combine engines consisted of
two parts — an intermittent portion covering 144 hours of
operation and a steady-state portion covering 56 hours. The
intermittent part is consistent with the duty cycle (SAE J708)
used for many years by the Nebraska Tractor Testing Laboratory
to test the performance of new tractors. The steady-state
part was selected to represent the maximum continuous load
that is likely to be placed on these engines, such as pumping
irrigation water.
Intermittent Part--Each engine was run through six power
settings with the engine speed controlled by the governor per
manufacturers' specifications as follows until 144 hours
were accumulated (16 hours on 8 hours off per day):
a. 85% of dynamometer torque obtained at maximum
power--40 minutes
b. Zero dynamometer torque at rated rpm--40 minutes
c. 42.5% of dynamometer torque obtained at maximum
power--40 minutes
d. Dynamometer torque at maximum power--40 minutes
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-73-
e. 21.25% of dynamometer torque obtained at maximum
power--40 minutes
f. 63.75% of dynamometer torque obtained at maximum
power--40 minutes
Steady-State Part—Each engine was run at governed speed and
75 percent of maximum torque around the clock until 56 hours
were accumulated. After 24 hours, the engines were shut off
for 2 hours for valve seat recession measurements and service
checks.
Farm Trucks
The engines were to be operated 16 hours on and 8 hours off
per day on the following duty cycle until 200 hours were
accumulated for each fuel.
a. 85% of maximum power (available at 3,000 rpm) at
3,000 rpm--40 minutes
b. 45% of maximum power (available at 3,000 rpm) at
3,000 rpm--40 minutes
c. 45% of maximum power (available at 2,500 rpm) at
2,500 rpm--40 minutes
d. 25% of maximum power (available at 2,000 rpm) at
2,000 rpm--40 minutes
e. 85% of maximum power (available at 3,600 rpm) at
3,600 rpm--40 minutes
Recreational Vehicles
The recreational vehicle test called for the engine to be on
16 hours and off 8 hours per day until 200 hours were
accumulated for each fuel. The engine was operated in both
intermittent and steady-state modes.
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Intermittent Part--The engine was operated in six speed and
power settings as follows until 144 hours were accumulated:
a. 85% of maximum power (available at 3,000 rpm) at
3,000 rpm--40 minutes
b. 45% of maximum power (available at 2,000 rpm) at
2,000 rpm--40 minutes
c. 85% of maximum power (available at 3,600 rpm) at
3,600 rpm--40 minutes
d. 45% of maximum power (available at 2,500 rpm) at
2,500 rpm--40 minutes
e. 45% of maximum power (available at 3,000 rpm) at
3,000 rpm--40 minutes
f. 85% of maximum power (available at 2,500 rpm) at
2,500 rpm--40 minutes
Steady-State Part — During the steady-state part of the cycle,
the engine was run at a setting that produced 100 horsepower
(52 percent of maximum power) at 3,000 rpm until 56 hours
were accumulated.
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Appendix 4
Engines Tested
1. John Deere "B" tractor; 2-cylinder I-head engine; rated
at 24 horsepower at 1,250 revolutions per minute (rpm);
4 11/16" x 5 1/2" bore and stroke, 190.4 cubic inch
displacement (CID). The engine was originally equipped
with ordinary cast iron cylinder heads with a hardness of
9-25 on the Rockwell C scale. The tractor was manufactured
between the 1930s and 1952. Similar tractors were manufac-
tured until about 1960.
2. Farmall "H" tractor; 4 cylinder I-head engine; rated at
24 horsepower at 1,650 rpm; 3 3/8 x 4 1/4" bore and stroke.
The engine was originally equipped with "special gray iron"
valve seat inserts having a hardness of 26-36 on the Rockwell
C scale. The tractor was manufactured between the 1930s
and 1953. Similar tractors were built until about 1958.
3. For "8N" tractor; 4-cylinder L-head engine; rated at 23
horesepower at 2,000 rpm; 3 3/16" x 3 3/4" bore and stroke,
119.7 CID. The engine was originally equipped with valve
seat inserts having a hardness of 39-43 on the Rockwell C
scale. The tractor was manufactured between 1947 and 1952.
4. International Harvester 240 tractor; 4 cylinders; rated at
27 horsepower at 2,000 rpm; 3 1/8" x 4" bore and strokes,
122.7 CID. The engine was originally equipped with an
ordinary cast iron cylinder head with a hardness of 12-23
on the Rockwell C scale. The tractor was manufactured
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-76-
between 1958 and 1962. Similar tractors were built until
1978.
5. John Deere 95 303 CID 6-cylinder combine engine; rated
at 80 horsepower at 2,500 rpm. The engine was originally
equipped with ordinary cast iron cylinder heads with a
hardness of 9-25 on the Rockwell C scale. The engine
was manufactured between about 1960 and 1974. A 4-cylinder
version of this engine also was used in combines and
tractors, and a 3-cylinder version was used in tractors.
6. Pre-1974 Chevrolet 292 CID 6-cylinder truck engine; rated
at 115 horsepower at 4,000 rpm. Prior to 1974, the engine
was equipped with ordinary cast iron cylinder heads. The
engine is still in production but now has induction-hardened
cast iron exhaust valve seats. The engine also has been
used in combines and other agricultural equipment.
7. Pre-1984 General Motors 454 CID 8-cylinder recreational
vehicle engine; rated at 210 horsepower at 4,000 rpm.
The engine has always been manufactured with induction-
hardened exhaust valve seats.
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-77-
Appendix 5
Farm Engine-Use Survey Form
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-79-
Appendix 6
How to Order Additional Documents Referred to in this Report
The following documents, referred to in this report, are
available in EPA docket Number EN-87-03. Copies may be
obtained by writing to Control Docket Section (LE-131A),
Environmental Protection Agency Gallery 1, West Tower, 401 M
Street, S.W., Washington, D.C. 20460. Telephone (202)
382-7548. The docket may be inspected between 8 a.m. and
4 p.m. on weekdays. As provided in 40 CFR Part 2, a reason-
able fee may be charged for photocopying.
1. Effects of Low Levels of Lead and Alternative Additives
to Lead on Engines Designed to Operate on Leaded Gasoline,
Final Report. Report by the National Institute for
Petroleum and Energy Research (NIPER) on results of engine
tests performed for this study (193+ pages).
2. Statements of work covering work performed by NIPER.
A. Effects of Low Levels of Lead and Alternative Additives
to Lead on Engines Designed to Operate on Leaded Gasoline,
Covers tests of leaded and unleaded gasoline performed
during fiscal year 1986 (10 pages).
B. Study of the Effects on Leaded Engines of Alternative
Additives to Lead. Covers tests of non-lead additives
performed during fiscal year 1987 (12 pages).
3. Quality Assurance Project Plan for Engine Testing Work
Performed by NIPER (23 pages).
-------
-80-
4. Interviewers Manual for Gasoline-Powered Farm Equipment
Survey. Survey conducted by the National Agricultural
Statistics Service, USDA during July 1986 (7 pages).
5. Survey Protocol and Quality Assurance Plan for Field
Measurement of Exhaust Valve Seats in Gasoline-Powered
Tractors. Survey conducted by the Radian Corporation
during September 1986 (84 pages).
U.S. Environmental Protection Agency
Region 5, Library (5PL-16)
230 S. Dearborn Street, fioom 1670
Chicago. IL 60604
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