76-25 AW
An Evaluation of a Diesel-Powered Taxicab
July 1976
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Mobile Source Air Pollution Control
Environmental Protection Agency
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Background
The Environmental Protection Agency receives information about many
systems which appear to offer potential for emission reduction or fuel
economy improvement compared to conventional engines and vehicles.
EPA's Emission Control Technology Division is interested in evaluating
all such systems, because of the obvious benefits to the Nation from the
identification of systems that can reduce emissions, improve economy, or
both. EPA invites developers of such systems to provide to the EPA
complete technical data on the system's principle of operation, together
with available test data on the system. In those cases in which review
by EPA technical staff suggests that the data available show promise,
attempts are made to schedule tests at the EPA Emissions Laboratory at
Ann Arbor, Michigan. The results of all such test projects are set
forth in a series of Technology Assessment and Evaluation Reports, of
which this report is one.
The conclusions drawn from the EPA evaluation tests are necessarily
of limited applicability. A complete evaluation of the effectiveness of
an emission control system in achieving performance improvements on the
many different types of vehicles that are in actual use requires a much
larger sample of test vehicles than is economically feasible in the
evaluation test projects conducted by EPA. For promising systems it is
necessary that more extensive test programs be carried out.
As part of an ongoing program to evaluate the feasibility of using
the Diesel engine as a powerplant for light-duty vehicles, the EPA has
conducted test programs to quantify the exhaust emissions and fuel
economy of a number of light-duty Diesel vehicles. Most of the vehicles
tested to date have been either production vehicles or manufacturer's
prototypes. The remaining vehicles are a mixture of light trucks and
passenger cars that have been retrofitted with Diesel engines.
The vehicle evaluated in this test program is a 1975 Dodge Coronet
retrofitted with a Diesel engine. The vehicle was assembled by Vehicle
Technology, Inc. (College Point, N. Y.), and is typical of a fleet of
about sixty Diesel-powered taxicabs operating in the metropolitan New
York area.
Test Vehicle Description
The test vehicle is a 1975 Dodge Coronet powered by a Chrysler-
Nissan 6 cylinder Diesel engine. The engine conforms to Federal and
California regulations for 1975 heavy-duty Diesel engines.
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The engine utilizes a prechamber type combustion chamber. The fuel
injection pump is manufactured by Diesel-Kiki. The transmission is a
Chrysler 3-speed automatic.
The vehicle was tested at an inertia weight of 4500 Ibs. A
tabulation of other vehicle statistics is presented on the Vehicle
Description sheet at the end of this report.
Test Program
Exhaust emission and fuel economy tests were conducted in accordance
with the 1975 Federal Test Procedure ('75 FTP) for light-duty Diesel
vehicles (Federal Register, June 30, 1975, Vol. 40, No. 126, Part III).
In addition to the '75 FTP, testing included the EPA Highway Fuel Economy
Test (HFET) and measurement of steady state emissions.
The vehicle was tested at two inertia weights. The first, 4500
Ibs., is the correct inertia weight based on the vehicle curb weight.
The vehicle was also tested at 3500 Ib. Tests at the lower weight give
an estimation of exhaust emissions and fuel economy if the engine were
to be installed in a lighter chassis.
At both inertia weights, the vehicle was tested twice according to
the '75 FTP and HFET. Steady state tests were conducted only at the
4500 Ib. inertia weight. Acceleration times from 0-60 mph were also
measured at both inertia weights. Acceleration tests were run on a
chassis dynemometer.
Test Results
Exhaust emissions and fuel economy of the test vehicle are summarized
below:
1975 Federal Test Procedure
mass emissions in
grams per mile ,., -,
(grams per kilometer)
4500 Ib. - avg.
of 2 tests
3500 Ib. - avg.
of 2 tests
HC
0.35
(0.22)
0.63
(0.39)
CO
1.4
(0.9)
1.5
(0.9)
NOx
1.85
(1.15)
1.79
(1.11)
Fuel Economy
(Fuel consumption)
21.3 miles/gal
(11.1 liters/lOOktn)
23.9 miles/gal.
(9.9 liters/lOOkm)
(1)
Values shown in parenthesis denote metric units.
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Highway Fuel Economy Test
mass emissions in
grams per mile ,..,.
(grams per kilometer)
Fuel Economy
HC CO NOx (Fuel consumption)
4500 Ib. - avg. 1.12 1.9 1.39 27.5 miles/gal.
of 2 tests (0.70) (1.2) (0.86) (8.6 liters/100km)
3500 Ib. - avg. - 1.8 1.37 29.8 miles/gal.
of 2 tests (1.1) (0.85) (7.9 liters/lOOkm)
(1) Values shown in parenthesis denote metric units.
Individual test results for the '75 FTP, HFET and steady state tests are
presented in Tables I-IV (following the text of this report).
Acceleration time from 0-60 mph took 38.8 seconds at 4500 Ib.
inertia, and 29.7 seconds at 3500 Ib. inertia.
The performance of the test vehicle was severely hampered by the
shift point calibration of the automatic transmission. Under full
throttle acceleration from rest, the transmission shifted into high gear
before the vehicle reached 30 mph. No downshift (3-2 shift) occurred
under full throttle acceleration above 30 mph.
By manually shifting the automatic transmission, better acceleration
rates could be achieved. At 4500 Ibs., acceleration time from 0-60 mph
was reduced to 27.6 seconds. However, even with this added assist,
vehicle performance is at best leisurely.
For fuel economy comparison purposes, the 1975 EPA Gas Mileage
Guide gives a '75 FTP fuel economy of 14 miles/gal, and a highway fuel
economy of 22 miles/gal, for a comparable Dodge Coronet powered by a 225
cu. in. 6-cylinder Otto cycle engine.
Conclusions
1. The Diesel-powered Dodge demonstrated emission levels below
those required by Federal regulations for 1977 light-duty Diesel vehicles.
It should be noted that the test vehicle had accumulated only 250 miles
at the conclusion of the test program. Further testing would be required
to verify that the exhaust emissions do not exceed allowable levels as
mileage is accumulated. Federal regulations required that new vehicles
meet applicable emission standards for 50,000 miles.
2. Compared to a production 1975 Dodge Coronet powered by a six
cylinder engine, the Diesel-Coronet demonstrated about 50% higher city
fuel economy and 25% higher highway fuel economy.
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3. In its present configuration, the performance capabilities of
the Diesel-Coronet are inadequate for some driving. Low speed performance
(under 30 mph) is acceptable, but entry onto freeways is difficult
because the vehicle cannot achieve enough speed while in the accelera-
tion lane to merge with traffic.
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Table I
Test #
4500 Ib. inertia
77-2172
77-2216
Average
3500 Ib. inertia
77-2301
77-2278
Average
1975 Federal Test Procedure
mass emissions in
grams per mile /,\
(grams per kilometer)
HC
CO
C02
NOx
miles/gal.
(liters/lOOkm)
0.33
(0.21)
0.37
(0.23)
0.35
(0.22)
0.63
(0.39)
-
0.63
(0.39)
1.3
(0.8)
1.4
(0.9)
1.4
(0.9)
1.5
(0.9)
1.5
(0.9)
1.5
(0.9)
472.
(293.)
481.
(299.)
477.
(296.)
430.
(267.)
418.
(260.)
424.
(264.)
1.82
(1.13)
1.88
(1.17)
1.85
(1.15)
1.80
(1.12)
1.78
(1.10)
1.79
(1.11)
21.4
(11.0)
21.1
(11.2)
21.3
(11.1)
23.5
(10.0)
24.2
(9.7)
23.9
(9.9)
1977 Federal Emission Standards
for light-duty Diesel vehicles
HC CO NOx
1.5 gms/mi 15.0 gms/mi 2.0 gms/mi.
(1)
Values shown in parenthesis denote metric units.
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Table II
•75 pi? individual Bag Emissions
in grams per mile
Bag 1: Cold Transient Bag 2: Stabilized Bag 3: Hot Transient
Test // HC NOx C02 CO MPG HC NOx CC-2 CO MPG HC NOX C02 CO MPG
4500 Ib inertia
77-2172 0.43 1.76 530. 1.5 19.1 0.20 1.95 454. 1.1 22.3 0.51 1.64 462. 1.5 21.9
77-2216 0.48 1.75 536. 1.6 18.9 0.22 2.03 467. 1.2 21.7 0.57 1.71 467. 1.6 21.6
3500 Ib. inertia
77-2301 0.68 1.70 482. 1.7 21.0 0.52 1.93 420. 1.3 24.1 0.81 1.61 410. 1.7 24.6
77-2278 - 1.65 462. 1.6 21.9 - 1.90 407. 1.3 24.8 - 1.63 404. 1.6 24.9
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Test # HC
4500 Ib. inertia
Table III
Highway Fuel Economy Test
Mass emission in
grams per mile . .
(grams per kilometer) ' '
CO
CO-
NOx
3500 Ib. inertia
Miles/gal.(liters/100km)
77-2173
77-2217
Average
1.12
(0.70)
-
1.12
(0.70)
1.9
(1.2)
1.9
(1.2)
1.9
(1.2)
368.
(228.)
362.
(225.)
365.
(227.)
1.33
(0.82)
1.44
(0.89)
1.39
(0.86)
27.2
(8.6)
27.8
(8.5)
27.5
(8.6)
77-2279
77-2302
Average
1.8
(1.1)
1.7
(1.1)
1.8
(1.1)
335.
(208.)
336.
(209.)
336.
(209.)
1.36
(0.84)
1.37
(0.85)
1.37
(0.85)
29.8
(7.9)
29.8
(7.9)
29.8
(7.9)
(1)
Values shown in parenthesis denote metric units.
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8
Table IV
Steady State
mass emissions in
grams per mile , «
(grams per kilometer)
HC CO C02 NOx miles/gal(liters/100km)
Idle 0.01 gm/min. O.lgm/min. 25.gm/min 0.19 gm/min.
15 mph
(24 kph)
30 mph
(48 kph)
45 mph
(72 kph)
60 mph
(97 kph)
0.17
(0.10)
0.56
(0.35)
2.13
(1.33)
0.98
(0.61)
1.0
(0.6)
2.0
1.2
2.0
(1.2)
1.5
(0.9)
296.
(184.)
264.
(164.)
295.
(183.)
398.
(247.)
1.51
(0.94)
1.19
(0.74)
1.24
(0.77)
1.54
(0.95)
34.1
(6.9)
37.9
(6.2)
33.6
(7.0)
25.2
(9.3)
Values shown in parenthesis denote metric units.
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