Performance of Methanol-Gasoline Blends in a Stratified Charge Engine Vehicle 760546
A series of driveability and chassis dynamometer tests were performed using various blends of methanol and gasoline in a stratified charge engine vehicle. The vehicle used was a 1975 Honda Civic CVCC. This vehicle is powered by a prechamber type stratified charge spark ignition engine.
The basic intent of this effort was to characterize how methanol-gasoline blends behave in a prechamber stratified charge engine vehicle. Since the stratified charge engine was designed to operate at overall lean air fuel ratios, the leaning effect of methanol blended with gasoline might not produce the general degradation of vehicle performance, emissions, and fuel economy reported for late model vehicles.
The test program was separated into two phases. The first phase was to determine the effect of methanol-gasoline blends on the drive-ability of the stratified charge engine vehicle. Blends containing 10% to 40% by volume of methanol in gasoline were tested. A weighted demerit system was used to evaluate driveability. Based on this system, vehicle driveability improved slightly with a 10% by volume blend of methanol in gasoline. A 15% by volume blend of methanol yielded vehicle driveability roughly comparable to the base gasoline alone. Further increases in the methanol content produced increased degradation of the driveability. The vehicle would operate on the 40% by volume blend but it was essentially undriveable. Cold weather tests using winter grade gasoline as a base fuel demonstrated that 10% methanol had approximately the same effect on driveability for winter grade fuels as for summer grade fuels.
Emissions and fuel economy of the vehicle operating on base fuels and base fuels blended with methanol were evaluated using a chassis dynamometer and the federal urban driving schedule. The addition of 10% methanol to the base fuels produced only very minor changes in the emissions and fuel economy of the vehicle. Not all indicated changes were statistically significant. Generally, HC emissions increased, CO emissions decreased slightly, NOx emissions decreased, and volumetric fuel economy decreased slightly.
General conclusions are that the CVCC vehicle tested suffered only slight degradation in driveability using a 10% methanol-gasoline fuel and vehicle emissions and fuel economy are not significantly changed by use of the 10% methanol blend.