Expansion Chambers and Development

by Shane


Excellent article, but no mention of expansion chambers, which are a large contributor to the way 2-stroke engines develop power.

Would a 2-stroke engine without the expansion chamber develop useful torque over a wider range? Would it have similar peak power to a 4-stroke of the same displacement? (450 2-stroke v.s. 450 4-stroke)

Better yet, with the great peak power that has been achieved with the expansion chamber, why have consumers not seen the development of a variable tuned length expansion chamber. For all the R&D put into 4-strokes over the years, it's hard to believe some simple mechanically or electronically governed device couldn't be developed to control the tuned length of an expansion chamber. Resonance chambers were tinkered with by manufacturers but really did not have the same effect as physically changing the tuned length did they?

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Mar 09, 2012
Water Injection
by: Anonymous

There is no space to add 9 inches to the belly of the pipe. The header could be lengthened that 9 inches but then it would be too close to the ground. A better solution is water injection which can easily be adapted to an existing setup. The water spray inside the header lowers the exhaust temperature which causes the waves to move slower and basically imitate a longer exhaust pipe. If I ever find the time I may make one to experiment with.

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