Abstract
Future exhaust emission targets and increasing customer demands call for the implementation of enhanced engine technologies, as well known from automotive applications, into small capacity engine categories. Especially the applied engineering solutions in the market of motor vehicles driven by engines up to 50 cm³ displacement have been significantly changed in the last years. Beside low cost technologies (air cooled two stroke or four stroke engines with carburetor), enhanced mixture preparation and exhaust gas after treatment systems come to use.
Highly technological two stroke engines are equipped with direct fuel injection systems in combination with efficient exhaust gas after treatment methods; in four stroke engine applications intake port fuel injection systems in combination with oxidation catalysts or 3-way catalytic conversion are established on the market. Several applications of new and innovative technologies have already been worked out in research programs and presented at several SETC conferences (please refer to the following papers: SETC 2006-32-0065 [1], SETC 2005-32-0098 [2] and [3] for the two stroke engines and SETC 2006-01-0404 [4], 2004-01-2105 [5] for four stroke engines). These technologies are now available in a pre-serial production status or as prototype engines.
Keywords: 4-stroke, 2-stroke, emissions, pollutant, costs, oil consumption, efficiency