To improve the identical exhaust power and torque of a 6-cycle engine and its exhaust performance by attaching a supercharging device such as a turbo-charger and a supercharger to an intake valve used exclusively for a mixture.

In a 6-cycle gasoline engine having an intake valve 1 which is supplied with a mixture produced in a carburetor 5 and used exclusively for the mixture, an intake valve 2 used exclusively for air and an exhaust valve 3, the intake valve 1 used exclusively for the mixture and the intake valve 2 used exclusively for air are severally equipped with a supercharging device 6 such as a turbo-charger and a supercharger and an air or water cooling intercooler 7. Thus in an engine having the same displacement and number of revolutions, larger power torque can be generated. In addition, more exhaust gas can be removed.