HeadSmess
Well-Known Member
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- May 17, 2010
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why dig this thread up?
the theory is sound...that two strokes have better volumetric efficiency. well, they apply power every downstroke dont they?
problem is that in 2 strokes, the exhaust port opens at halfway down the stroke... so the rest of the stroke isnt producing any power... a 4stroke keeps that exhaust valve shut for almost the entire downstroke, so utilising the maximum expansion.
1 full downstroke every two revolutions is mathematically identical to one half downstroke every revolution...
a 4 stroke has better VOLUMETRIC efficiency.
a 2stroke has better MECHANICAL efficiency, due to the simple fact it has way less moving parts.
(a radial 6 cylinder engine has better mechanical efficiency than a V6, and a V6 is mechanically more efficient than a straight 6.
why? theres less moving parts in the radial engine. only two main crank bearings versus 7 in the straight six... and only one conrod bearing does a complete revolution in the radial. all of them revolve in the straight...)
give me the 4 stroke. quiet, smooth, torquey...reliable.
2 strokes belong in dirt bikes
now let this thread die as it should!
the theory is sound...that two strokes have better volumetric efficiency. well, they apply power every downstroke dont they?
problem is that in 2 strokes, the exhaust port opens at halfway down the stroke... so the rest of the stroke isnt producing any power... a 4stroke keeps that exhaust valve shut for almost the entire downstroke, so utilising the maximum expansion.
1 full downstroke every two revolutions is mathematically identical to one half downstroke every revolution...
a 4 stroke has better VOLUMETRIC efficiency.
a 2stroke has better MECHANICAL efficiency, due to the simple fact it has way less moving parts.
(a radial 6 cylinder engine has better mechanical efficiency than a V6, and a V6 is mechanically more efficient than a straight 6.
why? theres less moving parts in the radial engine. only two main crank bearings versus 7 in the straight six... and only one conrod bearing does a complete revolution in the radial. all of them revolve in the straight...)
give me the 4 stroke. quiet, smooth, torquey...reliable.
2 strokes belong in dirt bikes
now let this thread die as it should!
