Abstract: An engine intake system including a supercharger of a type wherein the intake air drawn from the intake air inlet port is compressed by the pressure of the exhaust gas before it is discharged through the intake air outlet port. A coarse air cleaner is provided in the intake pipe leading to the intake air inlet port and a fine air cleaner is provided in the intake passage communicating with the intake air outlet port, so that the pressure drop at the intake air inlet port can be minimized.

Abstract: An internal combustion engine having supercharger including an exhaust manifold integrated with an exhaust chamber for weakening a pulsation of exhaust gas, and a bypassing passage connected to the exhaust chamber for bypasing the supercharger. The exhaust manifold and the exhaust chamber can be manufactured integrally with each other by casting employing only a cope, a drag and a core supported effectively.

Abstract: An exhaust gas recirculation system for diesel engines including an exhaust gas recirculation passage and a recirculation control valve for controlling the gas flow in the recirculation passage. A control circuit is provided for controlling the operation of the control valve. The control circuit receives an engine speed signal and a position signal which represents the angular position of the control lever in the fuel injection pump and closes the control valve to cut-off the exhaust gas recirculation when the engine speed signal becomes smaller than the position signal.