Emissions and fuel economy of a prechamber diesel engine with natural gas dual fuelling

A four-cylinder turbocharged prechamber diesel engine (Caterpillar 3304) was operated with natural gas and pilot diesel fuel ignition over a wide range of load and speed. Measurements were made of fuel consumption and the emissions of unburned hydrocarbons, carbon monoxide, and the oxides of nitrogen. Improvements in fuel economy and emissions were found to be affected by the diesel fuel-gas fraction, and by air restriction and fuel injection timing. Boundaries of unstable, inefficient and knocking operation were defined and the importance of gas-air equivalance ratio was demonstrated in its effect on economy, emissions and stability of operation.