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[quote=hightower99;772122] lubrication problems shared with 2 strokes makes them not suitable for racing[/quote]
What do you think those are ?
Coz there aren't any "lubrication problems" except from the emissions generated by burning oil in the fuel mix.
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[quote=The_Canuck;772240]Because Two strokes are innefficiant. The End.[/quote]
2-stroke is MORE efficient than a normally aspirated 4-stroker.
It's emissions that kills it for them and the racing world wanting to show it isn't esoteric and has bnefits for normal car in the street.
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[QUOTE=Matra et Alpine;772254]2-stroke is MORE efficient than a normally aspirated 4-stroker.
It's emissions that kills it for them and the racing world wanting to show it isn't esoteric and has bnefits for normal car in the street.[/QUOTE]
yeah I was a bit unclear, it more efficiant in terms of creating power but not emmissions wise, ie the burning of oil...
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[QUOTE=Matra et Alpine;772254]2-stroke is MORE efficient than a normally aspirated 4-stroker.
It's emissions that kills it for them and the racing world wanting to show it isn't esoteric and has bnefits for normal car in the street.[/QUOTE]
I'm pretty sure that it is more important to be seen as the winner in a racing world than it is to be seen having cars similar to road cars.
Besides, there are privateer teams / engine suppliers in LMP1 in both the ALMS and LMS and they could develop two-strokes and dominate the competition could they not?
Maybe it's some other restriction that keeps two-strokes out of the equation. I think there is a rule that says the car must be of a certain volume at a certain distance at idling throttle - maybe two strokes would be unable to pass this test or something.
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[QUOTE=Matra et Alpine;772254]2-stroke is MORE efficient than a normally aspirated 4-stroker.
It's emissions that kills it for them and the racing world wanting to show it isn't esoteric and has bnefits for normal car in the street.[/QUOTE]
Thermally?
I don't think so because normally a 4 stroke is going to have much better expansion ratio coefficient (ie expansion ratio versus compression ratio) than any 2 stroke. Also 2 strokes have less volumetric efficiency because even though they intake air through a transfer port under pressure they have alot less time to fill the cylinder and the exhaust is normally open during a large part of the intake/compression strokes.
2 stroke diesels are the exception because they have exhaust valves and use a direct intake port that is pressurized by supercharger.
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[QUOTE=Matra et Alpine;772252]What do you think those are ?
Coz there aren't any "lubrication problems" except from the emissions generated by burning oil in the fuel mix.[/QUOTE]
Sorry I meant that 2 stroke engines and Wankel engines both consume oil per design.
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Is it possible to build a paddle-operated manual gearbox? I'm not talking about DSG, I mean paddles + clutch.
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Should be. Most motorsport categories use something like that, although they usually have gearboxes which can be flatshifted and thus negate 90% use of the clutch.
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[QUOTE=hightower99;772354]Thermally?
I don't think so because normally a 4 stroke is going to have much better expansion ratio coefficient (ie expansion ratio versus compression ratio) than any 2 stroke. Also 2 strokes have less volumetric efficiency because even though they intake air through a transfer port under pressure they have alot less time to fill the cylinder and the exhaust is normally open during a large part of the intake/compression strokes.
2 stroke diesels are the exception because they have exhaust valves and use a direct intake port that is pressurized by supercharger.[/QUOTE]
All of this is not to say that a two-stroke couldn't be made to have OHC right? IT would be possible to have the Otto cycle with OHC yeah?
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[QUOTE=Kitdy;772374]All of this is not to say that a two-stroke couldn't be made to have OHC right? IT would be possible to have the Otto cycle with OHC yeah?[/QUOTE]
You want to keep the number of valves to a minimum in a 2 stroke otherwise you negate one of it's major advantages. The best design is that used by 2 stroke diesels and yes you could use the same design and run it on petrol. These designs only have exhaust valves that are operated by a cam.
It would not be efficient to have a typical 4 stroke design engine be run in 2 stroke mode.
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[QUOTE=kingofthering;772361]Is it possible to build a paddle-operated manual gearbox? I'm not talking about DSG, I mean paddles + clutch.[/QUOTE]
Why?
Normally in a paddle shifted gearbox the paddle controls a whole range of things.
When you press the shift up paddle it will normally release the clutch, shut the throttle valve quickly to drop the revs as fast as possible, select the next gear, engage clutch when engine RPM is matched.
When you press the shift down paddle it will normally release the clutch, open throttle to WOT if it isn't already to raise revs, select the next gear, engage the clutch with properly matched engine RPM.
What you are asking for is basically a sequential shifter that is mounted as paddles behind the steering wheel but that would make gear changes about as fast as sequential manual, and not nearly as fast as a semi-automated.
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[QUOTE=hightower99;772397]You want to keep the number of valves to a minimum in a 2 stroke otherwise you negate one of it's major advantages. The best design is that used by 2 stroke diesels and yes you could use the same design and run it on petrol. These designs only have exhaust valves that are operated by a cam.
It would not be efficient to have a typical 4 stroke design engine be run in 2 stroke mode.[/QUOTE]
Maybe the added weight and complexity would improve fuel economy, power and also you could also not have to add oil to the fuel - I think there would be many benefits to this design.
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[QUOTE=Kitdy;772401]Maybe the added weight and complexity would improve fuel economy, power and also you could also not have to add oil to the fuel - I think there would be many benefits to this design.[/QUOTE]
No it wouldn't if you are talking about your typical 4 stroke engine design being somehow used in 2 stroke mode.
Simplicity = 2 strokes biggest asset don't mess with it
Efficiency = 4 strokes biggest asset.
If you want to make 2 strokes more efficeint then you have to do so without increasing complexity, and you really need to deal with the emissions before it can be used in cars.
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I am not trying to start controversy or anything. I'm being serious here.
I would like to remind everyone that it is a good idea to research on your own what you have "learned" in this thread. There are a lot of half-truths being told...in particular by hightower99. I'm not picking on you hightower, I think it is cool that you want to know about cars. But lots of your info isn't 100% correct. Sorry if I offended anyone.
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[QUOTE=-What-;772573]I am not trying to start controversy or anything. I'm being serious here.
I would like to remind everyone that it is a good idea to research on your own what you have "learned" in this thread. There are a lot of half-truths being told...in particular by hightower99. I'm not picking on you hightower, I think it is cool that you want to know about cars. But lots of your info isn't 100% correct. Sorry if I offended anyone.[/QUOTE]
What have you found out that isn't correct?