Daves Compound Twin turbo XUD

[Ruan]

Pressure Ratio is simply the ratio of the inlet pressure to the outlet pressure...

So say a turbo is working at a PR of 2 (at atmospheric that's 1bar(14.7psi) of boost above atmospheric) That essentially multiplies atmospheric pressure to make 29.4psi Absolute (Since atmo is 14.7psi ...) Feeds into another turbo working at PR2 - That turbo then multiplies the inlet pressure (29.4psi absolute) by a ratio of 2 = 58.8psi absolute... Convert back to atmospheric = 44.1PSI...

So the way you work it out is ALL in Absolute

Atmospheric multipled by LP pressure ratio - 14.7 x 2 = 29.4psi
LP side multiplied by HP side - 29.4 x 2 = 58.8psi
Convert to Atmospheric - 58.8 -14.7 = 44.1psi