Two-stroke cycle engine
Two-stroke cycle engine
(OP)
Why a two-stroke cycle engine must have an intake pressure boost??
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RE: Two-stroke cycle engine
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Two-stroke cycle engine
RE: Two-stroke cycle engine
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Two-stroke cycle engine
Nothing?
That would be a problem, wouldn't it?
Therefore, it needs something to push the scavenging charge through the cylinder with positive pressure.
Most questions like this can be solved by thinking.
RE: Two-stroke cycle engine
This might be a counter-example to the general rule.
RE: Two-stroke cycle engine
Some diehard engine tuners even tune the intake runner.
B.E.
You are judged not by what you know, but by what you can do.
RE: Two-stroke cycle engine
(A few old, single speed, stationary diesels I think.)
As the load and corresponding exhaust pressures increased, the vacuum pulse of the exiting exhaust tended to decrease. You can estimate the maximum intake charge pressure and figure out why the desire for higher BMEPs has left this idea in the weeds.
RE: Two-stroke cycle engine
The slightly pressurized fuel&air charge can have higher velocity entering the cylinder, which means that more time can be spent evacuating exhaust
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: Two-stroke cycle engine
They use the reflected high pressure pulse from the convergent end of the pipe to push fuel/air mixture back into the cylinder that has escaped out the exhaust port. They only work over a narrow RPM range though (which isn't a problem in a snowmobile with a CVT).
RE: Two-stroke cycle engine
Some years ago Toyota had a very powerful 2-stroke engine with poppet valves of about 3 litres. The engine had forced induction but I seem to recall that Toyota reported that it could be made to run quite well without the blower.
The above is presumably the general idea of what EHudson was referring to.
RE: Two-stroke cycle engine
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: Two-stroke cycle engine
Ski Doo & Polaris use a similar system for reverse on some of their snowmobiles. Selecting reverse cause the engine to shut down and start again in reverse. There's some additional changes to the driven CVT clutch so it will work in reverse and I'd guess the oil pump has to work bi-directionally as well.
I believe the system accomplishes this solely by manipulating spark timing to get the running engine to slow down below idle then essentially kick itself into reverse by igniting the cylinders far enough before TDC.
RE: Two-stroke cycle engine
RE: Two-stroke cycle engine
Either way, if the ignition timing is done by simple means, it will probably not be happy about it.
The Bombardier "SDI" (semi-direct-injection) engines drive the snowmobile backwards by reversing the engine, but these engines are electronically controlled for both fuel injection timing and ignition timing, and the electronic controls manage the process of reversing the engine (very quickly, I may add), so those electronic controls are smart enough to know what to do with the injection and ignition timing when it's running backwards.
RE: Two-stroke cycle engine
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: Two-stroke cycle engine
RE: Two-stroke cycle engine
And, for the record, there were some old Mercury engines that reversed rotation for reverse.
RE: Two-stroke cycle engine
RE: Two-stroke cycle engine
B.E.
You are judged not by what you know, but by what you can do.
RE: Two-stroke cycle engine
RE: Two-stroke cycle engine
RE: Two-stroke cycle engine
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: Two-stroke cycle engine
RE: Two-stroke cycle engine