Analysis of a Turbocharged Single-Cylinder Two-Stroke SI Engine Concept

Power dense internal combustion engines (ICEs) are interesting candidates for onboard charging devices in different electric powertrain applications where the weight, volume and price of the energy storage components are critical. Single-cylinder naturally aspirated two-stroke spark-ignited (SI) engines are very small and power dense compared to four-stroke SI engines and the installation volume from a single cylinder two-stroke engine can become very interesting in some concepts. During charged conditions, four-stroke engines become more powerful than naturally aspirated two-stroke engines. The performance level of a two-stroke SI engines with a charging system is less well understood since only a limited number of articles have so far been published. However, if charging can be successfully applied to a two-stroke engine, it can become very power dense. This article outlines some of the challenges related to charging systems for a single-cylinder crank case scavenged two-stroke SI engine. Different charging scenarios were investigated and a charging system was selected and optimized to meet the scavenging and gas exchange needs of two-stroke engine. A 125 cc single-cylinder two-stroke engine with a turbocharger was simulated and tested successfully to a performance level of 400 kW/L.