73-13
Evaluation of Two Consumers Power Company
Vehicles Converted to Use CNG Fuel
January 1973
Henry L. Gompf
Test and Evaluation Branch
Environmental Protection Agency
-------
Background
Over the past several years the Mobile Source Pollution
Control Program has had the opportunity to evaluate in the
laboratory a small fleet of vehicles converted to operate
on liquid petroleum gas. Very fe\v vehicles with compressed
natural gas have been available in the Michigan area. Thus,
when Consumers Power Company offered two CNG-equipped vehicles
for testing, the Test § Evaluation Branch accepted this oppor-
tunity to broaden EPA's exposure to the use of an alternate
fuel. This evaluation also would allow simulation of inter-
mediate duty vehicle operation on compressed natural gas and
would thus represent an input to the intermediate duty vehicle
technology assessment.
Systems Evaluated
Consumers Power Company supplied two vehicles for EPA test.
The first was a 1972 Chevrolet Nova equipped with an automatic
transmission and a 250 cubic inch displacement engine. This
vehicle had been converted to dual-fuel operation and was thus
capable of running on either CNG or gasoline. The second vehicle
supplied was a 1972 Chevrolet van equipped, also, with an auto-
matic transmission and a 250 CID engine. The conversion of this
vehicle allowed operation on CNG only. The conversion systems
used were not commercially available kits, but were systems
assembled by the Consumers Power Company.
Test Procedure
Emission testing of both vehicles was performed according to the
1975 Federal emission test procedure as specified in the
July 2, 1971, Federal Register, Volume 36, Number 128, Part II.
The Nova was tested while operating on CNG and on gasoline for
comparative purposes. The van was tested according to light
duty vehicle procedures at basic ignition timing of 14° BTDC,
and at 8° BTDC to quantify the effect of small timing changes.
In addition, the van was tested under simulated intermediate
duty vehicle conditions (6000 pound inertia and 31.5 road load
horsepower at 50 mph).
To evaluate the effect on maximum power of using CNG, the Nova
was tested on an electric chassis dynamometer. Maximum power
was measured both with CNG and with gasoline.
-------
Test Results
Table I indicates the results of EPA's testing of the two
vehicles. Note that fuel consumption has been calculated based
on a carbon balance. Table II indicates the percent reduction
in maximum power associated with use of CNG compared to gasoline
Data is reported for 4 different engine speed conditions.
Conclusions
1. The use of CNG results in significant reductions in all
. three regulated emissions.
2. A major reduction in power capabilities was associated with
the use of CNG on the dual-fuel Nova.
-------
TABLE 1
1972 Chevrolet Van
1975 Federal Test Procedure
(all results in grams per mile)
Configuration
14° BTDC
5000* inertia
8° BTDC : -.
SOOOtf inertia
14° BTDC
6000tf inertia
Configuration
CNG
Date HC
CO
CO-
Fuel
NOx Cons.
Gasoline
10/11
10/12
10/13
10/16
10/17
10/18
1.75
1.51
1.06
1.84
1.48
1.73
1972 Chevrolet
Date HC
8/16
8/17
8/21
8/24
.94
.84
1.55
1.27
5.39
4.20
5.29
7.70
4.70
4.65
Nova
CO
1.56
1.58
6.55
5.99
624.9
586.2
658.9
704.1
652.4
648.5
C02
582.7
626.9
709.2
713.2
2.24
2.09
2.20
3.51
6.84
5.87
NOx
1.90
1.94
3.95
3.45
1.95 mi/It
2.07 " "
1.86 " "
1.62 " "
1.87 " "
1.86 " "
Fuel
Cons .
2.13 mi/1
1.98 " "
12.1 mi/g
12.1 " "
-------
TABLE 2
1972 Chevrolet Nova
Consumers Power Vehicle
Percent Reduction in Maximum Power
Associated with the Use of CNG
RPM % Reduction
2500 38%
3500 321
4000 32%
4400 44%
------- |