profile that can vary on the basis of the specific needing but in any case not lower than 270 u00b0 for the expansion phase of the engine while a very limited portion of the profile even only 2 u00b0 is destined to the other phases of the engine cycle in line of principle it will be of about 6 10 u00b0 for a two stroke engine and of about 12 20 u00b0 for a four stroke engine observing first fig1 and 2 of the enclosed drawings an embodiment of the engine according to the invention is shown providing an inner rotor disc 1 having a spiral shaped curve positioned inside the cylinder supporting block 2 the cylinder supporting block 2 has an inner circular shape and it is concentric with respect to the rotation axis of the rotor disc 1 curve space obtained between disc 1 and block 2 is the expansion space for the piston pistons 4 each cylinder 5 with the piston 4 rod 6 and wheel 7 is mounted with an inclination angle optimum with respect to the curvilinear shape of rotor 1 and in such a way that the corresponding wheel 7 always is in contact with the disc 1 examining the shaped profile of rotor disc 1 ascent ramp 8 of the spiral shaped curve or compression ramp is that part of the rotor curve 1 along which the compression of.