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Old 05-24-2012, 06:34 PM   #42
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Originally Posted by sporadic View Post
This is not accurately stated. The CFM most certainly is dictated by the turbo, by both the turbine side and the compressor side.
A small turbine housing will restrict flow, and a small compressor will restrict flow.
There is too much over-simplification in your explanation and the original poster needs to do far more reading on their own rather than expect to get all the answers here by non-professionals, including myself.
Go to the Garrett website and read everything before accepting anything you read here as fact.

EDIT: I'll add that I recommend not buying a single piece of your turbo kit until you can read, understand, and plot points on a compressor map relative to your power goals.
If you don't want to do any of this, then just buy a pre-made kit from a company that has done all the research already.
X2..Well stated my friend
Originally Posted by amoosenamedhank
Regardless of what you have for a turbo, your intake track and combustion chamber are not variables. Changing your turbo sizing will not change this. A larger turbo will reduce back pressure, this will result in better evacuation of the combustion chamber...therefor improving the VE of the engine.
What? Your intake tract might not be a variable but whats inside of it is. Do you understand how PSI, CFM, and VFR are all related? Changing the turbo will change this, or what would be the point in a turbo upgrade?

Thats why when you read compressor maps your either plotting of CFM or MFR (lb/min) on the X axis. Psi is figured in the Pressure ratio along the Y axis.

OP you have alot of reading to do. Even going off the garret site alone isnt enough. They too, over simplify things.
Heres little preview
CFM (cubic feet per min)=How fast the air is flowing
CFM is a measurement of VFR (volumetric Flow rate)

If turbos are too difficult to understand. Think of 2 rooms. 1 room is 10 X 10 and the other is 20 x 20. If you fill both rooms to 100psi and theyre both the same temp, and you hold the pressure. Which has more air? The larger. Sure if you decrease the temp in the smaller room you can get more air. But the same could be said for the larger. Or more psi would mean more air in both rooms. Get it?....This is similar to how turbos work. But this concept is stationary in y example.
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