Psi vs Cfm Options

[KOU In3]

Ok, I've always been led to believe that CFM was more important a measure than psi and that the larger turbos flow grossly more air at a given psi than their smaller brethren. I understand the basic part that the hot air produced when the turbo is overworked leads to a higher psi reading from the same quantity of actual air.

Here's where I start to get confused though: if we keep the intake charge's temperature constant through effecient intercooling shouldn't these values be the same? Basicly if you pressurize the manifold to 20psi using 120 degree air from a 14b or the same temp and psi from say a mammoth BR580 shouldn't this be using the same cfm of air?

Right when I think it all makes sense I talk myself back into the classic fallacy of 'dude it's 20 psi!'. Is the Someone straighten me out here please.

[KOU In3]

think that you're confusing yourself on this...hot air isn't going to produce more psi

Hot air is going to produce more psi. Not useful for performance but still more psi nonetheless.

Imagine a sealed 10 pound nitrous tank filled with air. Resting at 1100 psi at 70 degrees farenheit. Now since it's sealed, the amount of air in the tank isn't changing. Crank the ambient temperature up to 100 degrees farenheit though and the pressure (psi) of the air in that tank is going to rise. I think one of the laws governing gas expansion applies actually. PV=NRT or one of those. If I try to quote it I'll definate make an even bigger @ss of myself though.

Should be the same principle when pressurizing a manifold. Not saying that that's going to net a performance gain just that the hot air will result in a higher psi. You are right that I've confused myelf though.

I think I'm getting confused at how the turbo is moving more air at the same psi. If it's not due to the lower charge temp. Is the reading of what is being pressurized taken somewhere where I'm not getting this? Is the cubic feet of air measurement still a temperature sensative unit or an absolute?

Thanks for humoring me here.