Abstract
A knocking is the big factor which prevents improvement in an internal combustion engine's thermal efficiency. With the aim of understanding knocking better, light emission spectroscopy was applied in this study to examine preflame reactions that can be observed prior to autoignition. Light emission intensity was measured at wavelengths of 306.4nm (characteristic spectrum of OH), 395.2nm (HCHO). In this research, it measured about the generating phenomenon of the preflame reactions in different engine speed and octane number.
