Abstract: An engine unit operable independently or joined in multiples of two or more units for smoothing out the torque flow at slow speeds, each unit including a fuel-suction-compression assembly and a power generating assembly employing the same main shaft and separate valve shafts gear driven therefrom at a two-to-one ratio. Each assembly has a plate-like block bored out to provide a central cylinder chamber and two planetary cylindrical valve chambers. Fixed on the main shaft and rotating in said central chambers are two like rotors having cylindrical hubs and two arcuate segmental pistons extending diametrically therefrom to make smooth sealing rotational engagement with the walls of said central chambers. Fixed on said valve shafts are arcuate segmental valves making smooth sealing rotational engagement with said valve chambers and said rotor hubs.