The engine includes a cylinder; a first piston and a second piston that reciprocate in the cylinder wherein the first piston has a first end piston head; a first piston rod attached to the first piston at a second end of the first piston opposite the first end; wherein the second piston has a first end forming a second piston head; a second piston rod attached to the second piston at a second end opposite the first end of the second piston; a first connecting rod connected to the first piston rod and coupled to a power output shaft; and a second connecting rod connected to the second piston rod and coupled to the power output shaft. The first and second piston head move away from each other on a first power stroke of the first piston and a second power stroke of the second piston.