As the subject of this topic says I would like to know what is the Engine Volumetric Efficiency of a 2.4L (Sunfire 2000 GT) please.

It depends. A turbocharged motor can often exceed 100% volumetric efficiency, and even some race N/A engines can. If you are using it to plot on turbo maps, 85% is a good number to start with.





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thanks !
indeed It was to plot it on turbo maps .. I went on a website were things are pretty well explained : http://pergatory.net/turbo/turbochoose.html and I don't know if someone can help me out ( probably )

They said to find for 4 rpm range 4 mass air flow and then when you have those numbers you have to multiply them by the Engine's Volumetric Efficiency and then by the pressure ratio for each rpm numbers ...

I know that Pressure ratio is the outlet pressure turbo divide by the inlet pressure turbo but let say I want to run my car 7PSIg how do I know the ratio for each rpm??

that's the only thing that is giving me headaches for the moment your help would be appreciate please

The pressure ratio is the same at all RPM points, so lets say you have 12psi at the turbo, and the inlet has -.5psi (its a suction), then your pressure ratio is 26.7 / 14.2 = 1.88. Now, it doesn't really matter what the RPM is, because as long as you have 12psi at the turbo, and its sucking in air at -.5psi, then your pressure ratio is 1.88.







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thanks a lot that is what I thought hehe I was wondering How I could get different PSI on each rpm it was kind of weird !

heumm well thanks for your answer so now I presume that at about 3000 rpm the turbo is spooled up so from this point I'll do a linear line at the desired pressure from 3000 rpm to 6500 since the gas shut off is at 6500 ..

and I will start a line from 2000 rpm at 1 pressure ratio to the straight line I started from 3000 to 7000

for instance :11lbs/min = 2000rpm and 3000=14lbs/min and 6500 =39 lbs/mins
The boost is about 8.7 PSI (1.6)
(P2c/P1c)
2

1.8

1.6 _____________________

1.4 /

1.2 /

1 /
0 5 10 15 20 25 30 35 40 45 50 55 lbs/min

The numbers here are not the right ones it's only to know if the ''principe'' is good

Sorry for the Shema I did the best I could