the map is used too first see if the intended turbo is the right selection for the application, and if the airflow/pressure ratio falls within the graph it is used too calculate how much heat is going too be added into the compressor outlet air!
enigne capacity in litres X rpm X VE X pressure ratio
-------------------------------------------------------------------------= air flow (in cfm) (multiply by 0.07 for lb/min)
5660
boost press X atmopheric pressure (1.013bar)
-----------------------------------------------------------------=pressure ratio
atmopheric pressure
you plot your engines characteristics (airflow/pressure ratio) at a couple of points and see how much heat is being added,, you want really to aim for the highest efficiency possible (this is the % on the graph)
any good too you?
