Effects of EGR on direct injection gasoline engine

A large amount of EGR was introduced into a direct injection gasoline engine. According to the increase of EGR rate, it was found that the combustion at the late period is hastened in spite of reduction of the initial burning rate. In consequence, both HC and NOx were reduced by EGR. This suggests that the effect on acceleration of the leaner mixture's flame propagation by hot EGR gas becomes varied under the condition of the stratified mixture's stabilized ignition.