A modular revolving cylinder engine including at least two interdependent flywheels driven in rotation by a driving device (1) that rotates them in synchronization and in opposite directions. Each flywheel includes a plurality of equally spaced hollow pushrods that are reciprocally movable along stroke lines that are parallel and offset with respect to the central axis of rotation thereof and through which combustion gases from associated combustion chambers pass outwardly of the flywheels. End portions of the opposing pushrods engage during each rotation of the opposing flywheels during which time the oppositely directed combustion gases passing through the pushrods impinge on the outer end portion of the opposite pushrod to thereby provide thrust to drive the opposing flywheel in rotation in opposite directions.