A Study of the Relationships between Cycle-to-cycle Variations of Combustion and Heat Release Delay in a Spark Ignited Engine

To clarify the cause of cycle-to-cycle variations of combustion in a spark ignited engine, two types of combustion, conventional and fast burn (2-plug ignition), and two types of fuel, gasoline and propane, were tested and analyzed by measuring the cylinder pressure. An electronic computer was utilized for these analyses. From these analyses, it was established that cycle -to-cycle variations of combustion in a spark ignited engine were dependent on cycle-to-cycle variation of the air-fuel ratio of the mixture ; and that the shorter the heat release delay between ignition and start of heat release, the lower the cycle-to cycle variations of combustion.