Identifying the regularities of power change at the vehicle’s wheels when one or several engine cylinders are disabled

Abstract

The object of this study is the power system of internal combustion engines in wheeled vehicles operating under conditions of partial cylinder deactivation. The study addresses the problem of decreased wheel power due to mechanical (pumping) losses in non-firing cylinders, which limits the efficiency of cylinder deactivation strategies aimed at improving fuel economy. A new method has been developed to determine the work and power output of the engine during acceleration with one or more cylinders deactivated. This method enables direct and accurate assessment of vehicle performance under real-world operating conditions. Experimental tests were conducted on two vehicle types: a Daewoo Lanos 1.5i passenger car and a KrAZ-255B heavy-duty truck. In both cases, cylinder deactivation was implemented by cutting off fuel supply, and on the KrAZ-255B, additional drainage of residual fuel from high-pressure lines was used to eliminate injector resistance. The results revealed a notable reduction in wheel power when cylinders were disabled; however, eliminating mechanical losses in the deactivated cylinders significantly reduced this power drop. In the Daewoo Lanos 1.5i, the power loss decreased by factors of 1.44 and 2.98 when one or two cylinders were deactivated. For the KrAZ-255B, reductions of 1.1 and 3.09 were recorded. These results are explained by the mechanical drag caused by the pumping action of non-firing cylinders. When this resistance is removed, power transmission becomes more efficient. The distinctive feature of this study is the quantification of mechanical losses and their effect on vehicle performance under real conditions. The method can be practically applied to optimize powertrain efficiency, especially in heavy vehicles and systems operating under varying load conditions.