Carb Question

[Credzba]

I am having a new engine built for my mustang.
It's one of the std. 347 stroker engines with afr 185 heads and a moderate cam (cam not selected until we flow the heads).

At any rate, I was going to use my 289 performer intake from edelbrock and my 500 cfm card from edelbrock.
I considered going to a holley 750 dbl-pumper, but when I went to the Holley site and did the math I'd be lucky to need a 600 cfm carb.

Their formula for carb selection is
Engine size (CID) x maximum RPM / 3456 = CFM
CFM @ 100% volumetric efficiency

And they note most cars are 80% efficiency up to 89% on highly modified cars.

Well 347 * 6000 / 3456 = 602
at even 90% efficiency thats only 541

Based on that my 500 cfm carb will limit me some, but a 750 seems way overkill.

What is you guys experience?

 

[Great68]

I think that intake and 500cfm carb would choke your motor.

The formula only gives a ballpark, but I think you'd be much better off with a good single plane intake and a 750cfm carb.

You already have the extra cubes and good flowing heads, upgrade the rest to match.

 

[allcarfan]

check out the AFR website and see what they have done with an xe274hr cam and an xe282hr camshaft. You should probably go with the xe274hr for an OTS camshaft.

As for a Carburetor....Holley's math is correct, however, I think your engine is going to spin a little more than 6000 rpms. Again, check the AFR site. They usually use a Speed Demon 650 (they flow 753cfm of air). They use that carb with their box-stock AFR heads and the cam that I mentioned.

As for an intake. First of all, if you want to sell the performer 289, let me know. I think you should probably go with something like a weiand X-cellerator or an Edelbrock RPM with the center section notched. That performer intake is definetly going to inhibit your engine's potential.

Shane