Details relevant to the development of a dilute charge, four-stroke automotive spark ignition engine are described. Features of the engine include electronic air and fuel management. Demonstrated performance features include higher output and improved octane sensitivity relative to the base powerplant. Mechanical hardware was developed to control pulsed fuel delivery to the engine under electronic control within a 3 millisecond time duration, with a degree of atomisation superior to commercially available diesel injectors. A linearised high response throttle servomechanism was developed.