Quoted: two stroke engines and 4 stroke engines are very diffrent but each has their own advantage.
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Yep.
A 2 stroke has very few moving parts, some 2 stroke engines only have about 5 moving parts. So you know 2 stroke engines have very high revolution potental, I know where to get a 2 stroke engine that revs upto 40,000 RPM, I have that engine, I also have an engine that was tested at reaching 38,000 RPM.
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It's obvious that you are talking about model airplane engines here. You can't compare a gasoline powered enigine to one that runs on Alcohol, Nitromethane (lots of it in a 40krpm model motor), and about 20% oil content by volume in the fuel. You are comparing apples and pomegranates.
The highest Reving 4 stroke I've seen comes in about 15,000 RPM
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In racing applications (at the 500cc World championship GP motorcycle races which were the last gasp for exotic 2 stokes) 2 stokes rev to only about 13-14,000rpm. They sound faster than that due to their exhaust note, but exhaust expansion velocity dictates the rev range. Since the pipe timing is partially responsible for the intake timing it doesn't make sense to run the enging faster than the fuel will explode in the exhaust..
As for 4 strokes, even garden variety 600cc sportbikes rev to 15,500 these days. The Japanese and European markets got 19,000rpm 250cc 4 cylinder bikes back in the early 90's. And Fomula 1 cars go higher than that.
also with a 2 stroke engine (older models) requires what's known as a tuned exhaust system (tuned pipe). The pipe adjust how the scavageing is done, at lower, mid or high RPM. Unfortunately the older model 2 stroke engines do have some serous design flaws.
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The length of the pipe dicatates the RPM range it will produce power at. The volume and port timing are set to set to help that resonation (i.e. coming on the pipe).
In a perfect world 2 stroke engines would have the potental to generate 2x the power of a 4 stroke.
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Close but not quite-you have seen power outputs for 4 cycle motors double reliebly in the last decade. 2 strokes have not managed the same growth. One reason for this is that 2 strokes are very difficult to use fuel injection, and a lot more finicky when playing with ignition timing. Both of those have been critical to the improvements 4 stroke power output.
For example, 20 years ago a healthy RG500 Gamma (4 cylinder 2 stroke streetbike that never came to the US legally) made about 80hp. They were fragile and unreliable, especially when modified. This gives them 160hp per liter which is great, but they had shitty gas mileage, poor driveabililty, and they burned every drop of oil you put in them. My 2005cc GSXR1000 makes 162hp, giving a similar power per liter, but it has midrange, emmisions controls, and it's as reliable as a stone hammer.
When you put the motors next to each other and see that the 2 stroke inhales every stroke, it is actually burning exactly the same volume of air/fuel as a 1000cc 4 stroke to produce the same power per liter, but is only able to match power at peak. As a 2 stroke lover it's hard for me to admit it, but mechanically opening and closing valves is the way to go.
To my knowledge the 2 stroke was the first internal combustion engine.
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Nope, Mechanical valve actuation was first.
4 Stroke engines are commonly more fuel efficent. Currently they have numerous moving parts that control when the valves are opened, closed, etc. 4 strokes are more difficult to opperate over 2 stroke.
I guess it's debateable as to what's "more difficult" about operating a 2 stroke vs. 4 stroke engine, but with a 4 stroke you just put gas in it and go. On a two stroke you are adding or mixing gas, replacing rings, and fouling spark plugs on a regular basis.
There's more to the reason that 2 strokes aren't prevalent these days than just the EPA...
Dave