SDSB  79-16
                          Technical Report
              A Study of  One Gasoline-Fueled Engine Line
  Comparing Emission  Results Between  1969 Engines and 1979 Engines on
     Three Test Procedures:  the Heavy-Duty Transient Engine Test,
                  the Heavy-Duty 9-Mode Engine Test,
                and the Light-Duty Truck Chassis Test
                                  by

                          William B.  Clemmens


                                 and

                            Timothy P.  Cox


                             July, 1979
                                 NOTICE

Technical Reports do not necessarily  represent  final EPA decisions
or positions.   They  are  intended to present technical  analysis  of
issues using  data  which  are currently  available.   The  purpose  in
the  release  of such reports is  to  facilitate the  exchange  of
technical information and to inform the public  of technical  develop-
ments which may form the basis for a  final  EPA decision, position
or regulatory action.

              Standards  Development and Support Branch
                Emission Control  Technology Division
            Office of Mobile Source Air Pollution Control
                 Office  of Air, Noise  and Radiation
                U.S.  Environmental Protection Agency

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                          Table of Contents







Section                                                         Pflge






  I.  Summary                                                      *•




 II.  Test Procedure                                               2




III.  Test Engines                                                 *




 IV.  Results                                                      3




  V.  Conclusions                                                  *

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I.   Summary

     The 1977 Amendments to  the  Clean Air Act mandated EPA to set
new emission standards for heavy-duty  (HD) vehicles or engines for
model years 1983 and 1985.   These new standards were  to represent a
percentage  reduction  "from  the  average  of  the  actually measured
emission from heavy-duty gasoline-fueled vehicles or engines .
manufactured during  the  baseline model year."  The baseline model
year  was  defined  as the last model year  in which engines were
uncontrolled with  respect  to a  given  pollutant.   For the 1983 HC
and CO  standards,  the baseline model  year  (MY)  is 1969.  For the
1985  NOx  standards,  1972 and 1973  have  been determined to be the
baseline model  years.   (1972 was  chosen to reflect the fact  that
some  1973  models  were  already  equipped  with  NOx  controls).

     EPA has  initiated  a testing program to determine these base-
line  emission  levels.   This  testing program includes multiple
transient tests on each baseline  engine,  during which  emissions are
measured  by  the critical  flow venturi constant volume  sample
CFV-CVS technique.  Additional testing on each engine  includes the
current 9-mode  certification procedure modified to use the CVS bag
procedure.

     As part of the  testing  program,  current  technology  heavy-duty
(HD)  and light-duty  truck  (LDT)  engines  have  also  been  tested.  In
some  cases  these  late model  engines are direct descendents of the
1969  versions.   Results  from the  first such  family line  tested
showed  a  striking  contrast in emission  results between  the  trans-
ient  test  and  the current  9-mode  test.   This  contrast was  most
evident with carbon monoxide (CO)  emissions.   The  later  model  year
engines  from  this particular  engine  line  exhibit  significantly
higher  CO emissions not only over the transient test,  but also  when
compared to other  current  technology  engines  tested under the  same
transient  conditions.   The  contrast  for HC  emissions  was  not as
great.   The HC emissions  from  the  later versions of this  engine
line were comparable to other current technology engines.

      Interest  in  the CO contrast  led to  limited  experimentation
with  additional  emission  control  hardware  retrofitted  to  these
later model year engines.  Data  from these  tests  show that  CO  from
the modified  engines  was reduced by over 99  percent  on  the  9-mode
test  relative  to the  average of  essentially the  same  1969 engines.
Yet,  the  emission  levels  mesured on  the  transient  test from the
modified  late  model engines indicated only a  30-40  percent  reduc-
tion  (relative to  their  1969  counterparts).   The average  of the
1969,  350  engines  is similar to  the  estimated  1969  sales weighted
baseline.   Therefore,  the  CO  reduction from  the sales weighted
baseline  for  the modified  late model engines is  in  the  same  range
(35-43%).   The 1977 Clean Air Act  Amendments  require  a  90  percent
reduction of CO.

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                                -2-
     The high  level of  CO emissions  from these  engines on  the
transient test leads to  the  conclusion  that  these  particular  1979
engines actually pollute at levels approaching uncontrolled levels
in the real world.   Analysis of the brake specific fuel consumption
(BSFC)  supports  this conclusion  (Table 6),  if one  assumes  that
similar fuel rates  with similar CO levels  indicates a  similar
degree of applied control technology.

     The cause  for  the  high  CO emissions  on  the  transient  test
appears to be traceable  to the  particular  type  of  carburetor  (air
valve) used on the later model year engines.  Since the carburetor
calibration and  design  are  part of the emission  control system,  the
test data  generated  indicates  that  the  relationship between emis-
sion reductions  on the 9-mode and emission  reductions in  the  real
world can be highly dependent on the emission control system used.
Certainly,  for the engines tested, a reduction  of  CO emissions on
the 9-mode test  resulted in little reduction on the transient  test
procedure.

     The inclusion  of  an  engine  from  a  1979 LDT  in the testing
program generated  some  interesting data.   Based on  the  very  high
emission levels from  this engine,  one concludes that  emission
levels are quite sensitive to  load  (avg.  power).   The current  LDT
compliance procedure tests LDTs at a weight approximately equal to
empty  weight.   The  emission  sensitivity of  this  particular  LDT,
and, LDTs  in  general,  to load is of concern  only  if the  LDT  com-
pliance  procedure  does  not load the vehicles in  a representative
manner.

II.  Test Procedure

     The  program test   schedule  consisted of approximately  three
cold start transient tests per engine (reference Federal Register,
Vol.  44,  No. 31,  February 13,  1979;  Proposed Gaseous  Emission
Regulations - 1983 and  Later Model Year  Heavy-Duty Engines, Subpart
N).   In one case  (1979,  350-CID)  only  two tests were  run on  the
engine due to time constraints.

     Bag samples  from  a CFV  type  CVS  of  approximately  1500  SCFM
were used  to  collect emissions.   One deviation from the  Proposed
Rules  involved  collecting  a separate bag  sample  for each of  the
four  segments  that make  up  the  test  cycle.    The  Proposed  Rules
use only one bag sample  for the entire  cycle.   The  change  was made
for  the purpose of  collecting  additional data on  the  baseline
engines.

     In  addition  to the  transient  tests, one  to  three hot-start
9-mode  tests  (reference 40  CFR  86,  Subpart  D) were run on  each
engine.  The 9-mode  test cycle  was  modified  so that  the CVS tech-
nique  could  be  used to  sample  emissions.  The modifications  in-
cluded  lengthening the cycle  modes  from  one minute  to  five

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                                -3-
minutes Co  obtain  a sufficient  bag sample.   Also,  only  one cycle
(9-tnodes) was run instead of  the usual two cycles (18 modes).  This
was done to keep the length of the  test as short as possible.  Data
from the CVS 9-mode agrees well with data obtained by the Subpart D
test procedure (see Table 2).

     In  one case,  a late model  current  technology engine  was
obtained with the  engine in a  light-duty  truck (LDT) chassis.
Three  LDT  Federal  Emissions  Chassis tests were  performed  on this
engine/vehicle prior to removing  the engine.

III. Test Engines

     Some of the late model engines tested were, for all practical
purposes, direct descendents  (i.e., essentially the same engine) of
1969 engines.  One  1979 heavy-duty engine  and one 1979 light-duty
truck  engine, with the exception of emission control devices,
closely  resembled  two  1969  350-CID engines  (Table  1).    The  LDT
engine was obtained in a van-style  chassis.

     The  certified  configuration  of  the  1979  350-CID heavy-duty
engine included parameter calibrations  (i.e.,  engine mod), and AIR,
but  no EGR.   The  certified configuration  of  the 1979  400-CID
light-duty  truck engine  included parameter calibrations, EGR, EFE,
and a  260 cubic inch pellet-type  oxidation  catalyst  (OC).

     The 1979 400-CID light-duty  truck  engine was  tested before the
1979 350-CID heavy-duty  engine,  but after the two 1969 engines had
been tested.   The  light-duty truck was  the  first catalyst engine
tested at EPA  on the transient  cycle.   The extremely high CO data
on  the 400-CID  engine  compared  to  the  1969 engines  led  to some
limited  emission control  system  modifications  on  both  the 1979
400-CID  light-duty  truck engine  and  the  1979  350-CID heavy-duty
engine.   The  only modifications  to the  400-CID engine  was the
addition of an AIR  system (Table  1).  The 350-CID  heavy-duty engine
modifications consisted of  the addition  of the 260 cubic-inch
catalyst from the 400-CID engine  (Table  1),  and  the  use of unleaded
fuel.   No  other  adjustments  of  engine parameters or calibrations
were attempted.  Table  1  lists the engines and  the  various  config-
urations tested.

IV.  Results

     A comparison  of  mean  test  results between  the  1969  350-CID
engines  tested and  the  1979  engines in the  certified  configuration
is  shown in Table 2.  The transient CO  results from  the  later model
year engines  are quite high.   Possibly of equal  concern, however,
is  the relationship of  the  transient  CO  results to  the 9-mode
results  between  the four engines.   The  contrast  between the test
procedures  is  even  more graphically demonstrated  in Table 3, which
shows  the  effect of  the emission  control system modifications on

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                                -4-
the  1979  engines.   The modified control  systems virtually  elimi-
nated both CO  and  HC emissions on  the Q-modnl tent .   Yrt .  on  tho
transient  test,  the modified systems   showed  only a  marginal
improvement in  CO emissions.   The  modified  control system did,
however,  show  a  fairly significant reduction in  transient HC
emissions.

     Table 4 provides a perspective of the emission  levels  of  the
1979 engines  as a  percentage  of emission reduction from the average
of  the  parent   1969  engines.   Both  the  light-duty truck and  the
heavy-duty  late model  engines  in  their  modified  configurations
showed over a 99% reduction in CO on the 9-mode test. But,  on  the
transient  test, only a 35-43  percent reduction (Table  5)  in CO
emissions is  realized when  compared to the estimated 1983  standards
(based on  engines tested as  of March  15,  1979).  The HC  levels on
the  transient   test  did,  however,  show a significant  reduction
(Table  5)  from the  estimated baseline.   The certified config-
urations showed  a  75-82  percent  reduction while  the  modified
versions ranged from  82-92  percent reduction.

     Table 6   lists  the average brake  specific  fuel consumption
(BSFC)  over  the individual test  segments as determined by  the
carbon  balance method.  The BSFC  values between the  certified
configuration and the modified configurations  of  both the 350-  and
400-CID  engines vary more  than would be  desirable.   However,  it
should be  recognized  that  these measurements  are  taken over  a very
short time span (approximately 300  seconds).   Because of  the short
measurement time,  slight differences  in the measured values tend to
be magnified.

     The  general  trends of  the data,  however,  are  interesting.
For  instance, the heavy-duty 1979 350-CID 4-barrel  engine tends to
show better or equivalent  fuel economy on  the cold-start NYNF
(non-freeway)  segment than  the  1969  350 2-barrel engine,  but poorer
fuel  economy on the  hot-start  NYNF  segment  and both  LAF  (freeway)
segments.  The 1979  LOT  (400-CID  4-barrel)  engine,  on  the  other
hand, tends to  show  better  fuel  economy  than  the 1969 engines  for
all  segments  except the  LAF segment where  the  1969 and 1979 engines
are  nearly comparable.  The  exact meaning of these  trends is still
uncertain.  Hopefully, additional data from other engines  tested in
the  program will more clearly indicate fuel economy effects  of  the
marginal  CO  control  of the  late model  engines.   The data does,
however,  tend  to inicate  that  previous  claims  about  substantial
fuel economy  penalties associated  with more  stringent  9-mode
standards  (i.e.,  1979 HD   Interim)  may  be misleading in  terms  of
real-world fuel economy.

     Earlier it was  mentioned  that  the  400-CID light-duty  truck
engine  was obtained   in a  light-duty chassis.   Both EPA  and  the
manufacturer ran  several   light-duty  truck  chassis tests on  this
vehicle  (21.0  roadload HP).   The  results  in grams per  mile  are

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                                -5-
found in Table 7.  Of interest are the grams per mile derived from
the heavy-duty  transient  test,  also shown  in  Table 7.   Distance
traveled (miles) on the heavy-duty test are derived by multiplying
the average speed \J for each segment by the time spent within the
segment.  Grams per mile are then determined by substituting miles
traveled for BHP-HR in the standard cold/hot emission calculation.
V.   Conclusions

     The first  conclusion  to  be drawn from the  test  data is that
all configurations of  the  late model engines in  this  engine line
exhibit emission  levels  approaching uncontrolled levels  of  CO  on
the transient test.  These  levels  are of concern, especially when
comparing  this  engine   line  to  other late model  engines without
catalysts  (Table  8).   These  other engines exhibit only  about  50
percent  of the CO emissions  from the 350/400-CID engine  line.

     Several potential  causes  for  the high  CO  levels  can be hypo-
thesized.   First,  the  late model  350/400-CID engines  use an "air
valve" type 4-barrel carburetor,  which  has an auxiliary butterfly
valve  operated by air velocity.   The other  late model  engines
(Table 8)  use a more conventional  4-barrel carburetor.  It can be
hypothesized that under transient heavy loads, the mixture control
and distribution of the "air valve"  carburetor's  secondary circuit
or possibly the  overall control of  the secondary circuit may not be
as good  as the secondary  circuit  in the conventional carburetor.
Evidence supporting this hypothesis  can  be found by comparing the
transient and 9-mode  CO test results of the  1979 350-CID heavy-duty
engine in  the certified configuration (Table  2)  to the results of
the other  current technology  engines (Table 8).   The  9-mode  CO
results of the 350-CID  engine are slightly  lower than the CO levels
of other  engines.   Yet, when these  engines  are  exercised trans-
iently, as in the real  world,  over  the transient test cycle, the CO
of the 350-CID engine becomes  nearly double  that of  the  other
engines.  This pattern  of high CO appears to be followed by the LOT
400-CID engine  (Table  2)  which also  has an "air valve" (Table 3)
carburetor.

     Another  possible cause  for  the high CO  on the  late  model
350-  and 400-CID  engines  could be  lack  of  sufficient  air flow
capacity  in the AIR system.   The  lack  of oxygen  is  certainly a
factor  in  the CO  reduction on the 9-mode for the modified 400-CID
catalyst-equipped LOT engine (Table 3).   But,  further investigation
\J    EPA Technical Report,  "Selection of  Transient Cycles for
Heavy-Duty Vehicles," HDV 78-02,  June,  1978.

21    Federal Register, Vol. 44,  No.  31, February  13,  1979 Proposed
Gaseous Emission Regulations - 1983 and Later Model Year Heavy-Duty
Engines, Subpart N, §86.1344.

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                                 -6-
shows Chat both the 1979 350-CID  HD  engine and the AIR system added
to the  400-CID engine are nearly  identical  (pump calibration,
diverter valve, calibration,  and  pulley  ratio) to the AIR system on
the  1979  454-CID  engine.  Yet,  the 454-CID engine  exhibits less
than half  the  level of CO (Table 8) emitted by the  350- and 400-
CID  engines.  It  seems unlikely that this AIR  system could supply
sufficient air flow for a 454-CID engine and not supply sufficient
air  flow  for a  350-  or 400-CID engine.  Therefore,  lack of air
flow, although  not totally  discounted,  does not  appear  to  be  a
major factor in the high CO  levels.

     In contrast to the CO reductions shown on  the transient test,
HC reductions  tended  to be  rather  significant   (60-90%).  However,
even though  the transient HC reductions tended to be significant,
the  9-mode  test still overestimated the transient emission reduc-
tions by 10-30%.

     Another point  of  interest about the data from this  engine line
is that correlation for both  HC  and CO between the transient test
and the 9-mode test can be obtained.  Unfortunately, this  correla-
tion (Table 9) is  not meaningful in  an  engineering context.  It is
true for  this  engine  line  that  lower  HC and  CO  emissions on the
9-mode procedure produce lower transient emission results.  But for
instance,  even when the 9-mode CO emissions are totally eliminated
(i.e.,  intercept = 0),  the correlation  line would predict  over 100
g/bhp-hr of CO.on  the  transient  test (Table 10).  At the estimated
90 percent reduction standard of 1.3 g/BHP-hr HC and 15.6  g/BHP-hr
CO,  both  of the  predicted  9-mode  values (HC and CO) would be
negative,  -0.7 g/BHP-hr HC, and  -268 g/bhp-hr CO, totally  meaning-
less numbers.   Therefore,  it can be said  for  this  engine line in
the configurations tested, there is no  9-mode HC or CO  result that
would correlate to a 90% reduction  in real world emissions.

     A  final  point worthy  of discussion  is  the relation of the
derived grams  per  mile on the HD  transient  test  to the grams per
mile of the  LOT tests (Table 8).  While it is  recognized  that the
heavy-duty  test does  load the engine more  than the LOT test, the
test data almost   indicates  that for  power  levels at  some point
above the loads imposed during the LOT  test procedure,  the  1979 LOT
engine is nearly uncontrolled for CO emissions.

     Two  facts bear on the  impact  on ambient air quality  by LDTs:
1)  the  apparent   sensitivity of  the   LDTs  to load;  and  2)  the
Federal Emission  Compliance Procedure tests LDTs at  a weight
approximately equal to empty weight.  If the compliance procedure
loads LDTs in a representative manner,  then the  sensitivity to load
is of  little concern.  However, if the compliance procedure does
not  load the vehicles  in a manner representing  in-use loading, then
the  emission sensitivity to load  becomes  a  very real  concern.
Based on  the potential  adverse  air quality impact  if the  latter
case is true,  the  authors think the representativeness of the LOT
test loads should  be reexamined.

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                                                  Table 1

                                        Description of Engines Tested
Engine #
BLT8
BLT11
CTE6
PCTE6*
CTE3
PCTE3**
MY
1969
1969
1979
1979
1979
1979
CID
350
350
350
350
400
400
USE HP
HD 180
HD 166
HD 136
MOD 136
LOT 183
MOD 179
RPM
3798
3609
3198
3198
3742
3579
AECD
None
None
Air
Air
EGR/OC/EFE
EGR/OC/EFE
Notes:
AIR = air injection system.
EFE = early fuel evaporation system.
EGR = exhaust gas recirculation system.
OC  = oxidation catalyst.
                                                                         MOD
                                                                         OC
                                                                         AIR
CARBURETOR


2 Barrel

2 Barrel

4 Barrel

4 Barrel

4 Barrel

4 Barrel
GOVN


 Yes

 Yes

  No

  No

  No

  No
 * Same engine as CTE6
** Same engine as CTE3

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                                                  Table 2

                       Comparison of 1969 Engine Emission Results to Emissions Results  of
                          1979 Engines in Their Certified Configurations (Grams/BHP-HR)

Engine #
BLT8
BLT11
CTE6
CTE3
Manufacturer

MY
1969
1969
1979
1979

CID USE
350 HD
350 HD
350 HD
400 LDT
Transient 9-Mode
HC CO NOx HC CO NOx
9.57 169.70 4.70 11.05* 182.50* 3.68*
6.21 126.13 5.36 7.25 131.47 4.21
3.14 118.07 6.23 .79 14.62 7.83
2.21 131.81 2.32 .81 45.91 2.59
Results**
                                                                                                             oo
                                                                                                              i
CTE6
1979
350
HD
.770
13.17
5.89
 * CT mode determined from BLT11
** Raw emission measurements per 40 CFR 86, Subpart D

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                                                   Table 3

                            Effect  of  Modifications to 1979  Engines (Grams/BHP-HR)

Engine # MY CID USE
Certified Configuration
CTE6 1979 350 HD
CTE3 1979 400 LOT
Modified Configuration
PCTE6* 1979 350 MOD
PCTE3** 1979 400 MOD
Transient 9-Mode
HC CO NOx HC CO NOx

3.14 118.07 6.23 .79 14.62 7.83
2.21 131.80 2.32 .81 45.91 2.59

2.29 89.57 5.96 .21 .18 7.42
1.00 99.24 2.38 .06 2.46 2.76
 * Same engine as CTE6
** Same engine as CTE3

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                                                  Table 4

                                     Brake Specific Emission Reductions
                              as a Percentage of Average 1969 350-CID Emissions
Engine #
I. Average
BLT8
BLT11
AVERAGE
MY CID
Transient
USE BSHC BSCO BSNOx
9-Mode
BSHC BSCO BSNOx
1969 Emission Levels (g/BHP-HR)
1969 350
1969 350
II. Certified Configuration
CTE6
CTE3
III. Modified
PCTE6**
PCTE3***
1979 350
1979 400
Configuration
1979 350
1979 400
HD 9.57 169.70 4.90
HD 6.21 126.13 5.36
7.89 147.92 5.13
(% Reduction)
HD 60.2% 20.2% -21.4%
LOT 72.0% 10.9% 54.8%
(% Reduction)
HD 71.0% 39.4% -16.2%
LOT 87.3% 32.9% 53.6%
11.05* 182.50* 3.68*
7.25 136.47 4.18
9.15 156.99 3.93
91.4% 90.7% -99.2%
91.2% 70.8% 34.1%
97.7% 99.9% -88.8%
99.3% 98.4% 29.8%
  *  CT mode determined from BLT11
 **  Same engine as CTE6
***  Same engine as CTE3
                                                                                                             o
                                                                                                             i

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                                                     -11-
                                                   Table  5

                             Brake  Specific Emission Reductions   as  a  Percentage
                                          of  the  1969  Baseline***
Engine #
MY
CID
USE
BSHC
                                                                                Transient
BSCO
NOx
I.   1969 Baseline*** (g/BHP/HR)
     Estimated 1983 Standard***  (g/BHP/HP)
     (i.e., 90% reduction of baseline HC and CO  levels)
                                                 12.96

                                                  1.30
                                                   156.03

                                                    15.60
                                                      6.14
II.  Certified Configuration (% Reduction)

CTE6              1979         350             HD

CTE3              1979         400            LOT
                                                75.8

                                                82.9
                                                    24.3

                                                    15.5
III. Modified Configuration (% Reduction)

PCTE6*            1979         350             HD

PCTE3**           1979         400            LDT
                                                82.3

                                                92.3
                                                    42.6

                                                    36.4
  *  Same engine as CTE6
 **  Same engine as CTE3
***  Based  on engines tested as of 3/15/79 (approximately 75% of the  1969 market represented)

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                                                              -12-


                                                            Table 6

                        Average Brake Specific Fuel Consumption  (Ib/BHP-HR)  Over  the Transient Cycle

Engine No.
BLT8
BLT11
CTE6
PCTE6*
CTE3
PCTE3**

MY
1969
1969
1979
1979
1979
1979
Composite
CID USE BSFC
350 HD .659
350 HD .613
350 HD .723
350 MOD .838
400 LOT .636
400 MOD .687
Cold Start
NYNF LANF
1..317 .736
1.743 1.026
1.488 769
1.309 .773
.921 .678
.912 .722
LAF
.595
.517
.722
.663
.582
.633
NYNF
.819
.860
.994
.988
.692
.763
NYNF
.937
.807
1.054
1.055
.806
.863
Hot Start
LANF
.702
.732
.760
.788
.699
.761
LAF
.589
.532
.635
.853
.585
.646
NYNF
.873
.731
.805
.832
.598
.663
*    Same engine as CTE6
**   SAme engine as CTE3

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                                 -13-
                               Table 7

         Comparison Betweeen LDT Chassis Test Emissions (g/mile)
         	and HP Transient Engine Test Emissions (g/mile)	

                                       No. of
Engine #        MY    CID     Use      Tests      HC    CO    NOx     MPG

CTE3           1979   400     LDT

  MFC LDT Chassis Test                   3         .61  13.87  1.58   10.63*
  EPA LDT Chassis Test                   3         .73  15.30  1.47   11.20*
  EPA HD Engine Test                     3       4.09 243.60  4.28    5.28**

CTE6           1979   350     HD

  EPA HD Engine Test                     2       4.64 174.52  9.19    5.55**


BLT11          1969   350     HD

  EPA HD Engine Test                     3       9.25 189.08  8.02    6.40**

BLT8           1969   350     HD

  EPA HD Engine Test                     3      16.41 290.79  8.40    5.43**
*    LDT city fuel consumption
**   HD composite fuel economy

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                                                     -14-
                                                  Table 8

                     Emission Results from Late. Model Engines Tested to Date  (1/5/79)
(g/BHP-HR)
Engine #
CTE1
CTE2
CTE4
MY
1977
1979
1978
CID
391
454
404
USE
Cal. HD
HD
Cal. HD

HC
2.81
2.26
3.98
Transient
CO
59.02
48.69
54.56

NOx
6.71
6.92
5.01
9-Mode
HC CO
— —
.39 17.33
.63 18.07

NOx
—
7.38
5.00
1969 Baseline* (g/BHP-HR)

Estimated 1983 Standard* (i.e., 90%
reduction of baseline HC and CO levels)
12.96  156.03
 1.30   15.60
* Based on engines tested as of 3/15/79 (approximately 75% of the 1969 market represented)

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                                 -15-
                             Table 9
      Linear Regression of Transient and 9-Mode BSCO Emissions

                                 Transient   9-Mode  Transient  9-Mode
Engine No.    MY    CID    Use     HC (y)    HC (x)    CO (y)   CO (x)
BLT8         1969   350    HD       9.57     11.05    169.70   182.50


BLT11        1969   350    HD       6.21      7.25    126.13   131.47


CTE3         1979   350    HD       2.21      0.81    118.07    14.39


PCTE3        1979   350    MOD      1.00      0.06     89.57   185


CTE6         1979   400    LOT      3.14      0.79    131.81    45.94


PCTE6        1979   400    MOD      2.29      0.21     99.24     2.46



Linear Regression: y = mx + b        HC           CO

  Slope (ra)                        0.6793        0.322
  Intercept (b)                    1.7865      102.1713
  r2 =                             0.9647        0.7644

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                                     -16-
                                 Table  10
                Emissions Projected from Linear Regression
                                 (g/BHP-HR)
                                      Transient
                                    HC          CO
  9-Mode
HC        CO
   90% Reduction  from Baseline    1.3*

   Zero 9-Mode Emissions
1.3*
1.786
15.6*
102.17
-0.7161
0
-268.60
0
   *   Based on  engines tested as of March  15,  1979.
* US. GOVERNMENT PRINTING OFFICE:  1979- 650-029/0015

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