73-27 DWP
Evaluation of the Texaco Stratified Charge
(TCCS) M-151 Army Vehicle
June 1973
Emission Control Technology Division
Office of Air § Water Programs
Environmental Protection Agency
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Background
During testing in May of 1972 at MSAPC, it was determined that
the TCCS-powered M-151 vehicle met 1976 Federal emissions
standards. The following emission values are the average of
three tests performed at the EPA laboratory at that time.
Hydrocarbon 0.37 gin/mi
Carbon Monoxide . 0.23 gin/mi
Oxides of Nitrogen 0.30 gm/mi
Carbon Dioxide 551.6 gm/mi
Since that time a 50,000-mile durability test has been conducted
on this vehicle by Texaco under contract with the U.S. Army.
Although major engine and emission control system maintenance
was required during the mileage accumulation, Texaco claimed
1976 emission levels were maintained. Included in the main-
tenance was: four individual replacements of various catalytic
elements in the system; several ignition modifications; EGR
system cleaning; and major valve train maintenance.
As part of EPA's cooperative effort with the U.S. Army and EPA's
continuing interest in the emissions characteristics of this
engine concept a confirmatory test program was scheduled in the
EPA laboratory.
Vehicle Tested
The vehicle tested was an Army M-151 1/4-ton truck with a
four-speed, manual transmission. The vehicle was powered
with a 141 CID water-cooled, 4-cylinder, emissions-controlled
version of Texacofs stratified charge, multi-fuel combustion
process (TCCS).
The emission control system is schematically illustrated in the
attached Figure 1. The system included:
a. A cooled EGR system used to control oxides of nitrogen.
The system provided for two EGR rates. A high rate used
for part load operation and a low rate for high load operation.
The EGR system also incorporated a particulate trap and an
EGR mixing device.
b. A platinum loaded close-coupled catalytic reactor
whose design incorporated a tangental swirling action of
the exhaust to provide for turbulence and mixing. In
addition two reactors of a through flow design were
employed, one loaded with platinum, one with copper
chromite All catalytic reactors were Texaco designed
and fabricated.
c. Intake air throttling at idle and light load was used
to increase exhaust temperature during these modes of operation
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Test Program
A series of tests were conducted in accordance with the 1975
model year certification procedure. Details of this procedure
are described in the November 15, 1972, Federal Register. Steady
state testing was also conducted.
During the majority of the EPA testing, the vehicle was operated
on a mixture of Texaco no-lead pump fuel and a trace percentage
lubricating oil. Due to the oil in the fuel, continuous analysis
for hydrocarbon emissions was made using a heated flame ionization
detector. Limited gas chromatographic analysis of exhaust samples
was also conducted for methane content.
Test Results
The attached Table I presents the 1975 FTP emissions data compiled
during the EPA evaluation of this vehicle. It is apparent that
this vehicle met 1976 emissions levels. Also presented in this
table is fuel economy for the driving schedule based on carbon
balance calculations. The maximum speed data presented in this
table, and the typical high speed sections of the driving schedule
as given in Figures 2 and 3 illustrate that this vehicle could
not meet all the acceleration requirements of the driving schedule
and was not able to achieve the maximum 57 mph speed of the
driving schedule.
Steady state emissions and carbon balance fuel consumption is
given in the attached Table II. Fuel consumption data from
this table indicates the highest steady state fuel consumption
was at idle (1-73 gal/hr). This condition suggests that the
engine was tuned for inefficiency at this point to provide for
rapid cold start warm-up and elevated idle exhaust temperatures.
Exhaust samples from test number 356 were analyzed for methane
using GC analysis. The bag 1, 2 and 3 hydrocarbon levels were
respectively 4.25, .42, and .53 grams and were respectively
analyzed to be composed of 19.6, 86.7, and 38.6$ methane.
Conclusions
1. Although major engine and emission control system maintenance
was required, after 50,000 miles of durability testing a TCCS-
powered M-151 vehicle met the statutory 1976 mass emission
standards.
2. The vehicle demonstrated poor driveability and low power
throughout this testing.
3. Extensive use of catalytic reactors was required in Texaco's
emission control system.
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4. Trace quantities of lube oil in the fuel seemed to cause
no measureable additional heavy hydrocarbon component in the
exhaust as sampled during this testing.
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Table I
__i:'l'P Composite Results
Avg.* '76 STD
Test Number 325 326 335 346 356 . 366 ~
Unburned Hydrocarbon (gm/mi) °-96 °'^ 0-34 0.28 0.34 0.22 0.30 0.41
Carbon Monoxide (gm/mi) 7'66 2'53 °-61 O-52 l-°4 0.51 0.67 3.4
Oxides of Nitrogen (gm/mi) °-27 °-27 0.33 0.36 0.31 0.34 0.34 0.4
Carbon Dioxide (gm/mi) 616'54 573'66 594'21 6°8'67 559.06 540.05 582.03 ^
Fuel Economy** (mpg) 14'37 15'63 15'20 14'96 16.09 17.07 15.55 ,—
Max. speed during 505-secondy Bag 1 48 51 />— 43 49 45 48 --x.
high speed cruise (mph) (
Regulation calls for 57 mph 1 Bag 3 52 54 ^— 53 53 51 53 ,-^
* Emission Avg. Neglects Tests 325 and 326
** Fuel economy based on carbon balance assumes: Fuel 86.6% wt. carbon
Fuel density: 6.167 Ibs/gal
All tests conducted at 2750 Ibs. inertia; 9.9 rear wheel hp at 50 mph.
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Table II
Steady State Test Results
Gaseous Composition
Idle
gm/5 min.
0.06
0.12
0.42
1266.83
15 mph
gin/mi
0.14
0.00
0.06
151.42 3
30 mph
gm/mi
0.00
0.02
0.17
10.04
45 mph
gm/mi
0.02 HC
0.01 CO
0.25 NOx
174.49 CO,
Fuel Consumption*
N 344 Gear
^ 46.4 28.3 30.2 mi/gal
1.73 0.32 1.06 1.49 gal/hr
253.4 47.3 155.0 218.1 gm
*1. Loading characteristic is per belt-driven Clayton
Dynamometer set at 9.9 rear wheel hp at 50 mph.
2. Fuel consumption based on carbon balance.
Assumes: Fuel 86.6% wt. carbon
Fuel density: 6.167 Ibs/gal
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