In order to clarify the effect of ignition system on lean burn characteristics

experiment have been done with conventional spark plug ignition and active pre-chamber on a 0.5L Single Cylinder Research Engine (SCRE). The ways how to extend the lean burn limitation also have been investigated. The results show that

lean burn combustion can effectively reduce the fuel consumption and increase the thermal efficiency of gasoline engine. Adopting traditional spark plug system can extend the lean burn limit to excess air ratio of 1.5 with the gross indicated thermal efficiency of 45% limited by unstable combustion

while resembling active pre-chamber system can achieve GITE of 46.5% with the excess air ratio of 2.0 with the help of much more stable combustion. And the NOx emission of active-prechamber system has been reduced by 88% compared by conventional spark plug system. Increasing the compression ratio to 15 can further increase the GITE to 48% and reduce the NOx emission to lowest 58×10-6 (v/v) with the excess air ratio of 2.1.