The paper presents an algorithm to set the parameters of the dynamics of the classic mechanism the main of internal combustion. It shows the distribution of the forces (on the main mechanism of the engine) on engines with internal combustion. With these strong points and together with speeds of kinematic couplings shall be determined when the output of the engine heat shield. The method shall be applied separately for two distinct situations: When the engine is working on a compressor and in the system of the engine. For the two individual cases, two independent formulae are obtained for the efficiency of the engine. With these relations is then calculated with respect to the mechanical efficiency of the engine heat shield Otto, in four-stroke, for two-stroke engines and 4 stroke V. the final yield of the engine is obtained taking into account and thermal efficiency given by the Cycle Carnot program.