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Compression Ratio Cylinder Pressure Decay Chart

If a 2:1 and a 15:1 cylinder start at the same pressure, the 15:1 cylinder's pressure decays at a far higher rate and in so doing delivers the power to the crank mostly before 90 degrees after TDC is reached. Unless supercharged, a 2:1 cylinder would only achieve about 200 psi and as such, the difference in power be-tween the two ratios would be represented by the shaded green area.
Compression Comprehension

If a 2:1 and a 15:1 cylinder start at the same pressure, the 15:1 cylinder's pressure decays at a far higher rate and in so doing delivers the power to the crank mostly before 90 degrees after TDC is reached. Unless supercharged, a 2:1 cylinder would only achieve about 200 psi and as such, the difference in power be-tween the two ratios would be represented by the shaded green area.  View Related Article

 

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