Abstract: Disclosed herein is a rotary engine/pump for use as an internal combustion engine, a fluid motor, a fluid pump or the like. Included is a ring of a plurality of radially arranged inwardly projecting convex reactor lobes, an exhaust-intake rotor concentrically mounted in the center of the ring of reactor lobes and having a shaft therethrough journalled concentrically with the axis of the reactor lobe ring, and a multiplicity of secondary rotors each with a shaft therethrough rotatably mounted equidistant from each other intermediate the reactor lobes and the exhaust-intake rotor, with their shafts parallel to the shaft of the exhaust-intake rotor. Each of the secondary rotors has three radially outwardly extending legs defining a concave cavity between each pair of legs.