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.
Proceedings of the Small Engine Technology Conference, Madison, Wisconsin, September 1999, SAE P-348, ISBN 0-7680-0462-4.
Shawcross D., Pumphrey C., Arnall D., “A Five-million Kilometre, 100-Vehicle Fleet Trial, of an Air-Assist Direct Fuel Injected, Automotive 2-Stroke Engine”, SAE 2000 World Congress, Detroit, MI, March 6-9, 2000, SAE paper no. 2000-01-0898, p22.
Re all engines see Environmental Protection Authority, PA 40 CFR Parts 89, 90, and 91; Re marine engines see EPA, Federal Register 52087 October 1996.
Re utility engine see California Air Resources Board (CARB), “California Exhaust Emissions Standards and Test Procedures for1994 and Subsequent Model Year Utility and Lawn And Garden Equipment Engines”, December 1994; Amended 1995 in Mailout 95-29; Re motorcycles see ISO standard ISO 6460, 1981; Re chainsaws and brushcutters, etc., EPA regulations Phase 1, (USA + Canada), CARB II regulations (California only), and EPA regulations Phase 2.
Blair G.P., “Design and Simulation of Engines: A Century of Progress”, Keynote Address, Small Engine Technology Conference, Madison, Wisconsin, September 1999, SAE 1999-01-3346, JSAE 9938101, p.iii-xviii.
OPTIMUM Power Technology, “VIRTUAL 2-STROKE, Professional Edition”, Internet, optimum-power.com.
Blair G.P., “Design and Simulation of Two-Stroke Engines”, Society of Automotive Engineers, R-161, ISBN 1-56091-685-0, Warrendale, PA, February 1996, p623.
Heywood J.B., Sher E., “The Two-Stroke Cycle Engine”, SAE, R-267, 1999, p451.
Kenny R.G., Thornhill D.J., Cunningham G., Blair G.P., “Reducing Exhaust Hydrocarbon Emissions from a Low Cost Two-Stroke Engine”, SAE paper no. 982103, SAE Off-Highway and Powerplant Conference, Milwaukee, Wisconsin, September 1998.
Douglas R., “AFR and Emissions Calculations for Two-Stroke Cycle Engines”, SAE paper no. 901599 and also in SAE PT-69, 1998, p.209-220.
Blair G.P., “Design and Simulation of Four-Stroke Engines”, Society of Automotive Engineers, R-286, ISBN 0-7680-0440-3, Warrendale, PA, August 1999, p815.
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