Abstract: The invention can be used for transport means, sports cars and power plants. The inventive engine comprises a hollow toroidal working cylinder provided with a continuous circular slot embodied along the small diameter thereof, a nozzle or a spark plug and arc-wise extended input and output orifices embodied in the wall thereof for admitting air or air-fuel mixture and exhausting combustion gases. The transmission gear is provided with four eccentrics whose crankshaft necks are fixed to the axial holes of the pinions and arranged in the four bores of a fly wheel, whose axes are circumferentially disposed at an even pitch. The crankshaft necks are connected to the bearing elements through connecting rods each of which is arranged by the ends thereof in such a way that they are rotatable about the crankshaft neck and an axis disposed in the wall of one of the bearing elements.