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% ------- |