The Impact of Mechanical Losses on Engine Power of a Wheeled Vehicle under Cylinder Deactivation

A methodology for calculating mechanical losses in internal combustion engines has been proposed, enabling the assessment of the influence of the number of deactivated cylinders on the effective power output of a wheeled vehicle engine with an accuracy of approximately 10%. This method allows for the estimation of mechanical power losses and the mechanical efficiency (mechanical efficiency coefficient) under varying engine operating conditions. It has been determined that when half of the engine cylinders are deactivated, the nominal power output decreases to approximately 35–40% of its full-capacity level. The discrepancy between the experimental and calculated values of the mechanical loss power change coefficient does not exceed 8%. At the same time, the deviation between the calculated and experimental values of the engine load coefficient based on power remains within 5%. Additionally, it has been established that mechanical efficiency increases by up to 7% when the engine is operated at a 48% load level, which indicates improved energy utilization under partial load conditions. Furthermore, it was observed that as the number of deactivated cylinders increases, the magnitude of mechanical power losses correspondingly increases, while the mechanical efficiency of the engine decreases. This is primarily attributed to the redistribution of internal mechanical resistances within the engine and the non-linear behavior of frictional forces and parasitic losses under partial load regimes. A clear correlation between the mechanical efficiency and the effective engine power has been identified. Specifically, an increase in the number of deactivated cylinders (as a factor variable) leads to a rise in mechanical losses (as a response variable) and a reduction in mechanical efficiency. These findings provide a theoretical and practical foundation for optimizing engine control strategies in variable load conditions and contribute to enhancing overall fuel efficiency and operational performance of wheeled vehicles.