Improvements in a gas powered engine. Said improvements include use of a piston with a fixed piston arm that extends through a seal in the lower portion of the cylinder. In this proposal of four-stroke engine, the down chamber is used as supercharger for the upper chamber cylinder engine. In this proposed two-stroke engine the down chamber is used as a compressor chamber and the compressed air passes to the upper chamber. The piston arm operates on an elliptical crank that drives the output shaft. Valves that move air and exhaust into and out of the pistons are lifted by a cam located on the crank. A unique oil injector passes oil between the rings when the piston is in at the bottom of the stroke.