Combustion advancements in gasoline engines

This paper presents a critical review of the recent combustion advancements made in gasoline engines for the reduction of fuel consumption and engine-out emissions, and the technologies associated with these advancements. For optimum combustion throughout their speed/load range, engines should operate in three combustion modes: stratified-charge spark-ignited (SCSI), homogeneous-charge spark-ignited (HCSI), and homogeneous-charge compression-ignited (HCCI). Key technologies to achieve this, with maximum reduction in fuel consumption and emissions, are spray-guided direct-injection system, flexible variable-valve actuation, and, cylinder-pressure based engine controls.