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AnonymousWas trawling the net and come across this along with some articles on the same subject that seem like great idea, although they have been rolling around for a long time. From reading another article it appears that the technology will appear on a 2011 production snowmobile.
The irony in the ‘revolutionary’ design is that it’s a step towards becoming a 4 stroke
Some folks have questioned if the future of 2-strokes is limited, due to emission concerns, but not Eyvind Boyesen. He sees a solution to inherent 2-stroke engine issues via an exhaust trapping valve. Boyesen is an inventor and former top motocross racer who has always done his own wrenching and has a knack for coming up with new solutions to motorsport problems.
Back in 1972 he started Boyesen Engineering in Pennsylvania and started creating products for the motocross world and now much of the snowmobile industry. His firm makes reeds, dual reeds and now three-stage reeds to boost snowmobile engine performance. Then there’s the Rage Cage and PowerWings that enhance intakes for most modern sleds.
Boyesen now has a new prototype exhaust trapping valve. This valve is different from stock exhaust power valves in many ways. The trapping valve opens and closes with every engine revolution. In other words, the trapping valve closes the exhaust port so that NO fuel/air mixture escapes from the cylinder.
Valve comparison
Let’s compare Ski-Doo’s Rotax engine that’s equipped with RAVE (Rotax Adjustable Variable Exhaust) valves. This is a simple system that works with spring pressure. With more engine rpm, the more engine pressure and the more the RAVE valve opens. When the engine pressure drops, the RAVE valve closes. This is a great system for performance, it provides a small exhaust opening for low rpm and when it opens, it provides a large opening for the higher rpm.
This power valve system makes the engine run smoothly on the bottom and top. But the problem with it, and with 2-stroke motors in general, is the intake ports and exhaust ports are opened at the same time. This means some fuel/air mixture escapes without being burned, which causes poor fuel economy and poor emissions.
Boyesen’s new trapping valve is synchronized with the piston movement by mechanical means. By sealing the combustion chamber and allowing a longer time for the fuel to vaporize, one can eliminate poor volumetric efficiency or the loss of the fuel/air mixture in the 2-stroke engine. This elimination enhances the combustion process, which means more power and lower exhaust emissions.
Anonymous
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