Estimation of the possibility of using a simple thermodynamic model to evaluate the benefits of modifying a real spark ignition engine

Improving engine performance is the general goal of all designers of new cars. Nevertheless, there is and will continue to be a significant number of older cars on the market, where modifications can improve their performance in terms of fuel consumption and emissions, but also in terms of driving properties, giving the user fuel economy and greater driving pleasure. However, before starting the modification, it is worth knowing computationally what final effects we can expect. The paper shows that it can be estimated on the basis of simple thermodynamic calculations based on the basic Otto cycle, where the data for the calculations are very limited: they require geometric dimensions as well as pressure and temperature values provided by the selected compressor. The thermodynamic calculations of the cycle in two versions were shown, and the results were verified on a real engine while driving and related to the results of road tests and the chassis dynamometer.