The main goals of this paper were the creation of the model of the real Diesel engine in the Cruise M software package, the calibration of the model according to the available manufacturer's specifications and the indicated pressures measured on the test bench, and the optimization of operating parameters in order to obtain better engine performances. In the introductory part, the theoretical basis of Diesel engine operation were described along with elements that relate to the engine in question. This was followed by a description of multijet technology (the origin of the CDTI designation), eddy current brake and the procedure of measuring the indicated pressures in the cylinder together with the electronic elements used. The entire assembly was modeled in the Cruise M program and each component within the model was explained in detail along with the data required for its definition. With the end of the modeling, a preliminary simulation was started at the given engine loads in order to obtain the amount of deviation of the results from the known references and to see what needed to be changed for the calibration of the model. For this purpose, maps of fuel injection and boost pressure were mostly used along with individual geometrical characteristics of the components. After successful calibration, the model was optimized by varying the start and duration of combustion and by shifting opening and closing of the intake and exhaust valves for all cylinders. Finally, the comparison of the output characteristics after calibration and after optimization was shown and explained for all three engine load cases considering power, torque, specific effective fuel consumption and overall efficiency without the possibility of monitoring harmful emissions. In conclusion, the optimization of the model, including the actual engine in question, in order to improve the significant external characteristics of the engine, is possible by determining the optimal values of the influential operating parameters without the effect of complex structural changes.