REDUCING EXHAUST EMISSIONS AND INCREASING POWER OUTPUT USING A TUNED EXHAUST PIPE ON A TWO-STROKE ENGINE

At the 1999 SETC meeting, a paper presented a simple, tuned and silenced exhaust system for a two-stroke engine which theoretically reduced both noise and exhaust emissions and increased engine power and fuel efficiency. In this paper that design concept is applied to a small 56 cc industrial engine and experimentally shown to deliver the projected behaviour which was predicted in that earlier publication. Experimental test results are presented for power output, fuel consumption, and exhaust emissions to illustrate these statements.

An accurate engine simulation software package (VIRTUAL 2-STROKE) is employed to model the entire two-stroke engine and to demonstrate not only its effectiveness as a design tool in this area but also that it can accurately predict the above-mentioned performance and emission characteristics. By examining the output of the engine simulation it becomes possible to determine the gas dynamic and thermodynamic origins of the improvement in these performance characteristics and to inexpensively use that tool for further optimisation and enhancement of the engine performance and exhaust emissions.