OK. Now I have a good idea on how to fined the right compressor for my engine by maping my engine's air requierments at any given boost on a compressor map. You can do this using one of two equations

First the esiast one to use is CFM = (L x RPM x VE x Pr)/5660
where L=liters of your engine, VE= your engins eficiancy usaly between 85-95% and Pr= pressure ration found by the equation Pr=(14.7+(boost you are running))/14.7.

this worked for maping my t25 turbo out on my 2.0 liter sr20det pritty acuratly at 10psi.

the other one you can use is EVF=(engineCID)/1728 * (rpm/2)

then take the evf, witch is in CMF, and convert it to lbs/min using this formula

N=(P*EVF*29)/(10.3*T)

Where N is the airflow in lb/min, P is the absolute pressure in psi, and T is the absolute ambient temperature in Rankin.

Finally, multiply N by the volumetric efficiency of your engine (VE). This compensates for the fact that upon every cycle of the engine, not all of the old air/fuel mix in the cylinders is forced out the exhaust. Thus there is a difference .

Firs question is wich method is more acurate, second anyone know how to match the turbine to your engine?