A Hybrid Piston/Rotary engine has a stationary elliptical housing with a circumscribed inner cam surface to provide thrust, and sides with bearing supports for rotation of a rotor, at least one cylinder, a shaft with apertures therein to provide rotary valves combined with intake and exhaust ports within the bearing supports. Each cylinder has two opposed pistons connecting cam followers pivoted to the rotor which reciprocate upon rotation. During the intake stroke, the pistons separate as an intake valve opens; and fuel mixture fills the cylinder and closes as pistons compress the mixture. The rotor ports become aligned with the spark plugs within the bearing supports, and ignited gasses force the pistons apart causing the cam followers to provide thrust to the rotor. The exhaust valve is opened as the pistons contract. Four strokes are completed each rotation. The valves can also be arranged to operate as a pump.