Engine building faces important tasks to improve fuel efficiency, expand the fuel balance, increase power density, improve environmental performance, increase engine life and operational reliability. Combined internal combustion engines belong to the class of complex systems. When using a water-fuel emulsion, the smoke of exhaust gases and the change in the dynamics of heat release in engines always decrease. The physical model of the mixture formation process consists of fuel atomization, droplet propagation in the combustion space and the formation of a combustible mixture as a result of fuel evaporation. Modeling of such a process as combustion in an internal combustion engine can first be presented in a general form, taking into account the influence of factors in partial derivatives. For numerical simulation of the process of combustion of a homogeneous mixture, it is necessary to set the initial values for all spatial points at which the combustion process occurs, and two boundary conditions. When using a water-fuel emulsion, there is an improvement in fuel efficiency, an improvement in environmental performance, an increase in engine life and reliability.