Exactly the opposite! An engine's compression ratio is defined as the ratio of cylinder volume with the piston at the bottom of it's stoke to the volume with the piston at the top of its stoke ie 140 cubic inches at bottom and 20 cubic inches at top equals a ratio of 7:1. If an engine is turbocharged, the degree of turbocharging limits the engine's compression ratio. Although it doesn't change the compression ratio,it does increase manifold pressure as well as each cylinders mean effective pressure. As the pressure of the gas increases, so does the temperature. As a result turbocharging raises the temp of the fuel/air mix in an engine's cylinders and increases the possibility of detonation. Therefore, compression ratios must be limited to allow for the increased operating temps. The more boost your planning to operate at, the lower your compression ratio should be. hope i answered your question?
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