Abstract: A method of combusting natural gas fuel in a two cycle, turbocharged internal combustion engine substantially reduces the production of nitrogen-oxygen emissions. An improved turbocharger design provides increased air charging pressure, produces a controlled lean air/fuel mixture and lowers peak combustion temperatures. A jet cell ignition device ensures uniform, reliable ignition of the lean air/fuel mixture under all operating conditions and the lean air/fuel mixture in turn encourages complete fuel combustion and provides excellent combustion characteristics with methane, ethane and heavier paraffinic hydrocarbon fuels. These structural modifications and adjustment of other operating parameters combine to reduce nitric oxide (NO) and nitrogen dioxide (NO.sub.2) emissions by as much as 75% while effecting only a negligible increase in fuel consumption.

Abstract: A primarily oil-fueled engine is disclosed in which the engine compression ratio is established well below the level at which compression ignition of oil fuel will occur and in which the oil fuel charge is ignited by the discharge from a spark ignited, gas-fueled precombustion chamber. The compression ratio and peak firing pressures are similar to those encountered in a gas-fueled engine.