Abstract
reduction of the EFI engine noise with the application of the three acoustic resonators muffler is presented in this paper. By running independently, the noise of 368Q engine is found obviously to be the major noise source of the minibus. The measurement of sound intensity on the engine shows that the high noise of this kind engine is mainly caused by the intake noise. The three acoustic resonators muffler is designed by the theory of Hemholtz-Kirchlhoff and rationally linked to the intake pipe of the engine, which can reduce the intake noise of the engine dramatically and raised the power of the engine slightly under ordinary rotational speed. At the same time, the oil pan and timing gear cover are afresh designed with low noise concept. Good result of noise control is achieved.