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Percentage of gain/per point of compression

General engine tech -- Drag Racing to Circle Track

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houser45
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Percentage of gain/per point of compression

Post by houser45 » Sun May 17, 2020 9:14 am

Methanol engine. Sbc 11.0 to 1 compression with a flat top piston. Same engine with 12.0 to 1. Hp and torque gain of 2% ? Would it possibly be more?

Walter R. Malik
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Re: Percentage of gain/per point of compression

Post by Walter R. Malik » Sun May 17, 2020 11:47 am

houser45 wrote:
Sun May 17, 2020 9:14 am
Methanol engine. Sbc 11.0 to 1 compression with a flat top piston. Same engine with 12.0 to 1. Hp and torque gain of 2% ? Would it possibly be more?
The lower the initial compression, the more the increase will be ... going from 11/1 to 12/1 I would imagine to be about 2 to 3 percent; If there is not a piston dome in the way of ignition.
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Coloradoracer
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Re: Percentage of gain/per point of compression

Post by Coloradoracer » Mon May 18, 2020 6:51 am

As Walter said, piston dome will affect that, but also so will combustion chamber shape......piston dome impedes the flame front.....but poor combustion chamber shape affects it as well....then toss in camshaft and dynamic compression which is what the engine really sees.......it all starts piling up......
Mark Goulette
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