A rotary engine includes a casing having a large circular boring, a small circular boring, whereby the small circular boring interconnects with the large circular boring. A piston rotor is carried in a rotating manner within the large circular boring in the casing. A power head, ported to pass exhaust gases thru it's hollow center shaft, is carried in a rotating manner within the small circular boring in the casing. The piston rotor and the power head are meshed together to properly rotate during operation, with the piston rotor rotating counterclockwise and the power head rotating clockwise. A second powerhead can also be used.