If the compression ratio on a stock SR20DE is 9.5:1 and ideal compression readings are around 178 psi, is there a way to calculate what the compression ratio should be if the motor was built to be 11.3:1? Is it just a ratio or is there more involved?


Steve

Originally posted by thepep
If the compression ratio on a stock SR20DE is 9.5:1 and ideal compression readings are around 178 psi, is there a way to calculate what the compression ratio should be if the motor was built to be 11.3:1? Is it just a ratio or is there more involved?


Steve

They are not the same readings. Compression ratio is a measure of how much the gas is compressed from bottom dead centre to top dead center (ie: 11:1). The compression readings (ie PSI) is a measure of how well your valves and pistons seal the air in the cylinder. They can relate somewhat but not directly as you are asking.