Abstract: An engine includes a generally cylindrical housing divided into inlet, combustion chamber, and power housing portions. A shaft is rotatably mounted in the housing. A compressor element is mounted on the shaft for rotation in the inlet portion, an intake and exhaust valve rotor element is mounted on the shaft for rotation in the combustion chamber portion, and a power element is mounted on the shaft for rotation in the power housing. The valve rotor is provided to regulate the flow of compressed air into and out of the combustion chamber. Fuel injection and ignition are suitably timed to occur generally between intake valve closing and exhaust valve opening. Combustion products exit through the exhaust valve into the power rotor. These products rotate the power rotor to drive the compressor and valve rotors. The working surfaces of the compressor and power rotors are helices. The pitch of the compressor rotor helix decreases between the inlet end of the housing and the combustion chamber.