[steve25]

Here's a darn handy chart from Superflow to print off .

On the left is air flow at a 10" depression, you will need to multiply these numbers by 1.67 to attain numbers at 28".

On the bottom is your motors cylinder CID.

The right hand column is the HP per cylinder you should be able to produce when all is right.

So fo example let's take a 400 CID motor and round its cylinder CID off to 50.
Your running a head that can flow 234 cfm@28".

You should be able to make 60 hp per cylinder ( 480 HP total) , but you will then find that peak HP will not take place until 5000 rpm like the chart is showing you.
Info like this should help to make wiser choices in terms of cylinder head flow and Cam's

[Half-Inch Stud]

10" is more attainable all day longk. The chart is something for us money-saving home flow folks.

[steve25]

Well if for whatever reason if you have numbers at 28” and want them at 10” the just times them by .598.

[johnta1]

Here you go for the 28" conversion

[Stan Weiss]

It would have been nice if the table went high than 334 cfm.

Stan

[srmmmm]

Originally Posted by johnta1

Here you go for the 28" conversion

My engine seems to follow this very close:

6X-4 Heads - stock, should flow 206 cfm @ .500 lift

I'm using Comp XE275HR with 1.5 rockers, lift is .510"

Stroked 350 block to 413 cu in

Dyno result for peak was 453HP at 5600rpm.

[Skip Fix]

I want to think the formula for HP for one cylinder at 10" is .43xcfm.

[steve25]

Yes Skip it is.
, this chart should get folks well into the ball park so to speak.

Also note that this chart was really stated to be more for finding the rpm of peak HP, then the dead on amout of peak HP since there are so many more veriables .

[Stan Weiss]

I believe this will be pretty close to the chart.

Peak HP RPM = 1000 * (cfm / cid) * 2

Stan

[Skip Fix]

Steve my mentor old machinist had one of the first flow benches around and used 10" and gave me that number. He also had one of the few dynos back then a gauge one you had to watch. to get numbers! And your motor could "run the numbers". Shop across the street had a newer Superflow dyno later that was a good 25% higher on the same motor. Guy that owned that shop was a racer that died in a crash so he bought the shop and took a day or so to calibrate it correctly to read right on.

Why when I see dyno numbers I want to see a time slip with mph and wt to see how close it is if the numbers are real.

[steve25]

Skip the problem with using flow numbers taken at 10” is that the velocity is at the low end of what is normally encountered.

In a running motor the depression can range from 0 to 145”.

[Skip Fix]

Understood, and even comparing the same head using both pressures it can tweak numbers in different areas-so then which is "correct" ?

[J.C.you]

Many years ago I remember flowing my old superchiefs at 10” local shop and they went 510@.900 hehe, then at Meauxs 430@.900. I mentioned it to Meaux and he said very possible on a small bench, so I would be suspect anything at 10”

[Skip Fix]

JC usually the 10" I have seen are less than the 28".

[steve25]

It’s by far really more of a deal like what J C posted.

[70GS455]

And when the depressions are at some other non-standard value, there is a formula: new_flow = old_flow * sqrt( new_ depression/old_depression)


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[steve25]

Stan I agree, and had I made the chart I would have left off all below the useless 40 cfm@10 / 2000 rpm line and extended the higher cfm range.

Anyway for a whole lot of folks here this going up to 334 cfm and 70 CiD per cylinder serves a good purpose.

[Half-Inch Stud]

Now, where is that "Choke CSA" CFM vs RPM equation when you need it?

To extend to 367 CFM and 80 CID CYLs: Print, add extended scales, extend them straight lines, and Be happy.

[Skip Fix]

Then you have what type of bench-laminar flow(I think KRE has or had one of those) or "regular", then single orifice or multiple? How well was it calibrated-how many plates for all the ranges? All kinds of variables to try and compare "apples to apples" even on the same head.

We sent my High ports up to Dwayne Porter to flow to compare to Dan Brton's big Superflow here when he ported them for me and my buddy's "little" Superflow 110-3 different set of numbers! We bought some of the "pass around" calibration plates and got his 110 a lot closer-they were originally less than either of the big Superflows. Dwayne does a lot of mopar sstuff-my buddy is a mopar guy-but he has done a set of Pontiac High Ports before.

[Formulas]

How does VE. fit in these calc's ?

Its assuming 100%?