The impact on engine performance of controlled auto ignition versus spark ignition with two methods of load control

This paper presents and discusses results taken from Lotus’ Research Active Valve Train (AVT) engine, in which advanced combustion strategies can easily be investigated because of a the functionality of its Fully Variable Valve Train. In particular, Controlled Auto Ignition can readily be initiated and controlled by a method of early exhaust valve closure and late inlet valve opening to trap exhaust gas residuals within the cylinder from one cycle to the next. The paper looks at the impact on fuel consumption and emissions (engine out BSNOx, BSTHC and BSCO) of Controlled Auto Ignition versus Spark Ignition with load control either by conventional variable density throttling or by Early Inlet Valve Closure with variable lift. The points analysed are commonly used emissions comparison points: 1300rpm 2.95bar BMEP, 1500rpm 2.62bar BMEP, 2000rpm 2bar BMEP and 2500rpm 2.62bar BMEP.