The Effects of Fuel Preparation on Hydrocarbon Emissions of a S.I. Engine Operating Under Steady-State Conditions

This study investigated the effects of three fuel delivery systems (port fuel injection with production injectors, port fuel injection with air-assisted injectors and a premixed, prevaporized fuel system) on engine-out hydrocarbon (HC) emissions from a four-cylinder spark ignition engine.

Comparative tests were run at three part-load conditions and a wide range of EGR. Other engine parameters examined were intake-air and coolant temperatures, and injection timing. The observed effects of injection timing on HC emissions were related to the intake-flow events, which, in turn, affect in-cylinder fuel evaporation and combustion.