Abstract: An internal combustion engine in which a rotor or turbine is driven by the exhaust gases of interconnected double acting pistons. The three parallel pistons are interconnected by pinion gears engaging racks on the sides of the pistons. Improved mechanisms are disclosed for coordination of the movement of the pistons, the manner in which the intake and exhaust valves are operated, the manner in which the engine is started, and the manner in which the firing of spark plugs is timed. A control wheel is provided for starting and valve operation. A cam connected to the pinion gears operates sets of points to fire the spark plugs.