A rotary engine includes separate combustion chambers for receiving pressurized air and fuel mixture. An air chamber stories pressurized air/fuel  into a combustion chamber to be mixed for combustion to drive a piston. The combustion chamber is forced open during a firing cycle to allow expanding gases into a piston chamber. A valve seal serves as a base against which the expanding gases react to force a piston in a forward direction. The piston is coupled to a crank shaft which may in turn be coupled to a transmission or other power drive device to harness energy created by the turning crankshaft. A lifter includes a cam that rotates to raise and lower the combustion valve such that it moves upwards and away from the seal to optimize the amount of energy that is directed against the piston. Through series of timing gear, the amount of movement necessary to lift the valve is minimal.