Abstract
It is necessary for engines to improve thermal efficiency and reduce pollutant. It is one of the best ways to improve thermal efficiency to make compression ratio higher. However, in spark-ignition engines, knocking occurs due to the rapid combustion of the end gas. In this study, the measurement of the temperature history was made till the time of the occurrence of the knocking in a spark-ignition engine with a laser interferometry. This is a non-intrusive measurement method and high resolution of temperature is expected. The pressure and temperature at knock were investigated under various conditions of engine speed, spark timing, equivalence ratio and volumetric efficiency.