EMISSION AND CONSUMPTION REDUCTION FOR SMALL TWO-STROKE GASOLINE ENGINES 2001-01-1827

Automotive pollutant emissions have been drastically restricted during the last ten years. These emission standards are now concerning small two-stroke engine. A Lot of technologies are offered to automotive engine manufacturers, such as direct injection or catalyst converter, but needs for low production price do not allow small two-stroke engine designers to use such evolutions.

So, despite its high weight and complex mechanic, today's trend is towards four-stroke cycle.

In order to meet future emission standard, different concepts have been implemented on a small two-stroke engine. An optimum combination between boost pressure and port timing has been found, using CFD, connected with results from hydraulic simulation, in correlation with tests on engine. The intake required conditions are reached through an external device, which is giving the right in-cylinder scavenging flow.

Significant gains have been observed, concerning pollutant emissions as well as fuel consumption. These concepts allows small two-stroke engine to meet future regulations, keeping its advantages in price and weight.