I haven't looked up anything on how to calculate the air flow rate into an engine.
So that said here's what I did:

444 in^3 x 3200 rpm / 2 = 710,400 in^3/min => 411 cfm

This would be the air flow rate for a n/a 7.3L at perfect efficency.
One thing I did find online is a factor called Volumetric Efficiency (VE).
Apparently this is basically how well the air flows into the cylinders.
Also for most street engines this equals 80%.

An engine will always be the same volume displacement. So if you change the pressure at the manifolds, you actually changing the number of atoms of air that flow into the cylinders. You only notice the volume change if you take those atoms and return them to atmosheric pressure.
So, now I would assume to calculate the air flow rate for a turbocharged or supercharged engine you would calculate the n/a flow rate and then use the ideal gas law to find the actual # of molecules traveling through the engine. I did this and got 1.08 lbmol/min. Then since in the IGL V, R, and T are assumed to be constant (which T isn't, but I will account for this when I have more time.), we can obtain P1/n1 = P2/n2. Therefore, n2 = n1 * (P2/P1). Then you can plug n2 back into the IGL with atmosperic pressure to find the volumetric flow rate through the filter, and don't forget the VE of 80%.

So now we have:

Boost @ 3200 rpm (psig) Atom Flow Rate (lbmol/min) Air Flow Rate(cfm)
0 1.08 329
15 2.16 568
20 2.52 764
25 2.88 873
30 3.24 983
35 3.60 1092
40 3.96 1201
45 4.32 1310
50 4.68 1420
55 5.04 1529
60 5.40 1637
65 5.76 1747
70 6.12 1856
75 6.48 1966

I hope that A this is correct and B that it helps people choose the right filter set-up for their rather than just buying something that's popular or an upgrade.

For me, what filter's can I buy that flow 1100 cfm?

EDIT: Well, thats a bunch of crap, the columns aren't lined up right! The first and third columns are the one that matter anyway.

As of this thread being 1 1/2 pages long, the following chart was added.
I used 60% VE instead of the 80% used above.

Boost (psi) Air Flow (cfm)
0 247
15 426
20 570
25 654
30 737
35 819

 

Well, with that math, the stock filter box would collapse.

 

Clay says the 6637 flows around 525

 

So that's about good for a stock truck.
Interesting, I'm going to NAPA now anyway, I'll what they have to say.

 

You missed my first post.

With a stock truck, and the numbers you posted. The stock filters wouldn't flow enough air for normal driving.
A stock truck might make 20 lbs of boost if your lucky.

And I bet that filter don't flow more than 200 CMF.
Which is more than half of 500.

 

The stock napa filter(6417) replacment says it has 320 cfm. The napa 6637 says it's 425cfm. So if that equations is right might as well put on a bell and window screen like a puller would to let the engine breath that or get a bigger filter.

 

So I guess you have to get online because the parts guy could only tell me the dimensions of filters, not the flow rates or anything else for the matter.

 

Check this out. Engine Design Equations Formulas Calculator Air Flow Rate
Thats closer to a calculation.

 

Found a better site.
Air flow (CFM)
That says my V-10 should flow about 450 max cfm and my filter is rated at 500. Why would they under rate all the 7.3's like that? We must be missing some part in the equation?

 

So then you think my math is wrong?

 

Well if you use the 3.0 it tells you to in that second link, and plug that into the first link for the PSD, it comes out to 1230 cfm.

 

Those calculations have to be way simplified. Certainly, an engine, for example a PSD, turning 3200 rpm pushing 15 psi boost uses way less air than one pushing 45 psi boost.

 

Now I found this we must be missing something somewhere. This one shows you are at about 470 cfm with my quick numbers not to exact but if i filled it out right who knows??? motorgeek.com :: Turbo/Engine Flow Calculations and Maps

 

the 6637 flows 425 CFM. you have to look at the volumetric efficiency more.. there is no way we can ever reach 100% VE.. we would probably be lucky to see 75% with ported heads and everything.. i would probably assume more like 60% for a PSD's VE.. our head design really really REALLY sucks!! That math didn't look right either. I think that we do need more air flow through the filter, but not that much.. i simply don't think our stock turbos could ever suck that much air. find out the CFM rating on the stock turbo????

 

If we know the displacement per rotation, and multiply that times the # of rotations per minute that gives displacement per minute.
If you know the volume,temperature and pressure of a gas such as air, you know how many molecules there are.
If you know how many molecules in a set displacement and times that by the rate of displacement, you get how many molecules displaced per minute.
If you know how many molecules per minute and you know the temperature and pressure of the molecules you can find the volume as a rate with respect to time.

What am I missing? There is either some short cuts that people take and some assumptions they make or I have my logic wrong.