Increasing Engine Efficiency of 4 Stroke
Methods to improve efficiency of fourstroke, spark ignition engines at part load Abstract The four stroke , spark ignition (SI) engine pressure–volume diagram ( p – V ) contains two main parts. They are the compression–combustion–expansion (high pressure loop) and the exhaust-intake (low pressure or gas exchange loop) parts. The main reason for efficiency decrease at part load conditions for these types of engines is the flow restriction at the cross sectional area of the intake system by partially closing the throttle valve, which leads to increased pumping losses and to increased low pressure loop area on the p – V diagram. Meanwhile, the poorer combustion quality, i.e. lower combustion speed and cycle to cycle variations, additionally influence these pressure loop areas. In this study, methods for increasing efficiency at part load conditions and their potential for practical use are investigated. The study also incl...