Engine-Fuel Relationships with L.P.G. and Natural Gas

Several parameters of engine-fuel relationships with leaded and unleaded LP-gas and natural gas are discussed. Performance factors include the effect of carbureted gaseous fuels on observed and corrected volumetric efficiency.

Emphasis was placed on the knock-limited spark advance (KLSA) characteristics as a function of engine speed for all fuels tested at engine compression ratios of 9.1 and 10.6. Results showed that the knock-limited spark advance increased with decreasing engine speed with both LP-gas and natural gas fuels. The amount of change or increase appeared to be related to both fuel types and relative fuel octane quality as referenced to the engine requirement.