The Potential of Small Loop-Scavenged Spark-Ignition Single Cylinder Two-Stroke Engines

The applications of small loop-scavenged, single cylinder, two-stroke spark-ignition engines are widespread due to the specific advantages of this engine concept. Today's engines have, or will soon have, to face stringent pollutant and noise emission regulations and fuel consumption reductions. Advanced technical solutions will have to be applied even in the most compact and lightweight high output power units, which are represented in this paper by a chainsaw and by the most demanding form, namely the two-wheeled, which still has the highest specific output of all homologated vehicles. This paper presents the preliminary solutions, the state-of-the-art research and development and the author's view on the chainsaw and two-wheeled applications and an outlook focusing on the problems especially where the detailed pollutant emissions and their reduction are concerned. Comparisons with the four-stroke cycle and other two-stroke cycle scavenge principles are made. Technical data and detailed dimensions of low emission engines are listed, as well as the exact ingredients of gasoline and two-stroke oil. A comparison of the pollutant emissions of CO, HC, NOx, PAH, aldehydes, ketones and phenols for different vehicle categories is also given.