The effects of intake backflow on in-cylinder situation and auto ignition in a gasoline controlled auto ignition engine

► The intake backflow decreases as the intake valve open timing delays until it disappears. ► The in-cylinder mean temperature reduces as the intake backflow increases. ► Intake backflow lowers the hot zone temperature with more uniformed distribution in the cylinder. ► The hot and relatively low residual gas fraction zone grows up as the intake backflow increases. ► The experiment results validate the effects of intake backflow on auto ignition.