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Old 12-21-2011, 11:28 AM
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Steve Barcak Steve Barcak is offline
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Quote:
Originally Posted by ho428 View Post
My question about these huge stroker cranks is at what length is the return deminished performance wise?
Other than valve shrouding using larger valves the whole down side of the 326 and 350 was the B/S ratio, with the bore being so small vs stroke, but it was still around 1:1. Using 2.5 and 2.75 strokes in a 4.25 bore or less block the B/S ratio is considerably worse than the 350, much less the 326.
You're also doing the same thing percentage wise of valve size vs the B/S ratio in a 4.25 or smaller bore and a 4.5 or larger stroke.

Are we breaking a threshold of piston speed with the longer stroke that overcomes this?

Inquiring minds just want to know since I've never built such a large engine or understood the theory on these long stroke undersquare engines.
I am not sure there is a limit. Everytime Pontiac increase the stroke, it made more torque and, generally, there is no replacement for displacement ( other than supercharging or N2O ). You just move the power curve down the rpm scale depending on many other factors- rod length ( limited by deck height ), head and induction capacity, etc.
It is the same way with other engines too. or they would not make giant engines with monster strokes.

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