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Old 11-12-2019, 03:54 PM   #1
2 wicked
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Default Calculating dual quad cfm requirement

Hey guys, my son wants to go faster! We are going to build a new engine. We mud drag and bog. Currently have 557 with tfs 325 heads and mafia intake. Bought a svo A460 block and almost ready to order new heads and intake from TEA. They will be tfs 360 cc A460 heads and tunnel ram with dual dominators. This is probably a dumb question, but how do u figure proper cfm per carb. Engine will be 572/598 cid. Turning 7200/7500 rpm. I can't seem to find a dual quad cfm calculater. Thanks cory
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Old 11-12-2019, 04:34 PM   #2
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Default Re: Calculating dual quad cfm requirement

I'm kind of going thru the same process (Thought process) Just about the same size engine, heads and rpm range.

The air requirements of a 600" engine at 7,200 with 110% VE is 1,375 cfm. BUT

I've been told that two 1,050's would be better than two 950HP's and two 1,200's would be better than two 1,050's.

The goal for max power is to get intake vac below 1".

http://www.candsspecialties.com/ratings1.html

" Engines that need a broad RPM range such as Road Racing or Circle Track currently work best generating about .8 to 1 inch of mercury. Heavy drag cars will work at .6 to 1 inch depending on weight to horsepower ratio. Some light drag cars such as Pro Stock and Dragsters have C&S carburetors so large they generate only .1 to .2 inches of mercury vacuum and work very well at the high RPM narrow RPM range for these cars. "

Do you need two 1,400's to get a vac reading of 1" +/- in a 600" engine at 7,400 ?

What will those heads flow ?
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Old 11-12-2019, 04:41 PM   #3
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Default Re: Calculating dual quad cfm requirement

put 2 1150 Domi's on it and it will work
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Old 11-12-2019, 05:17 PM   #4
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Default Re: Calculating dual quad cfm requirement

Tunnel ram carb cfm = 2 x hp, 1100 x 2 = 2200 dry flow cfm
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Old 11-12-2019, 05:38 PM   #5
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Thanks for the info, I did find a cfm calc for multi carb setup and it suggested 1133 cfm range. The A460 heads from TEA are flowed on a 4.6 bore and spec [email protected] lift int and [email protected] lift. If I remember correctly, when I called them. We have a gen 3 1150 on current setup. Just have to buy another. Thanks again cory
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Old 11-12-2019, 06:49 PM   #6
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Default Re: Calculating dual quad cfm requirement

With the block and two carb setup your going to gain 150-200lbs on the front.
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Old 11-12-2019, 07:50 PM   #7
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BBF612, we have a c9 block now. It's filled half way into water pump ports with hard block. We didn't weigh it but sure a lot heavier than our Xtra block laying in the shop. How much does a A460 block weigh? Guess I figured it weighed more than a stock u nfilled block, by 20/30 #s. Just hope new engine when done puts us were we want to be. Thanks cory
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Old 11-12-2019, 08:00 PM   #8
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Default Re: Calculating dual quad cfm requirement

Cool deal, just found this.

http://www.429-460.com/t4189-race-engine-weights
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Old 11-12-2019, 08:17 PM   #9
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Default Re: Calculating dual quad cfm requirement

Quote:
Originally Posted by BBF612 View Post
Tunnel ram carb cfm = 2 x hp, 1100 x 2 = 2200 dry flow cfm
Seems kind of a crude calculation. Do you know where it came from, it's origins or anything behind it ?

Is it just a rule of thumb that works ?
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Old 11-12-2019, 08:25 PM   #10
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Default Re: Calculating dual quad cfm requirement

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Originally Posted by G-Code View Post
Seems kind of a crude calculation. Do you know where it came from, it's origins or anything behind it ?

Is it just a rule of thumb that works ?


LOL, just a good place to start, study enough engine builds, emc magazines, interweb builds, ect.

"3. Todd's engine. FRPP SVO block, 4.600" X 4.500"= 598 CID, TFS A-460 heads, TFS 2 X 4 tunnel ram manifold, two QFT 1150 carbs, Mezeire electric water pump, Moroso vacuum pump, dry sump pump and lines, Peterson dry sump tank, & nitrous plumbing. 735 lbs."


I used two 750hp bodies on my FE that I'm sure was flowing more than 750 cfm.

Last edited by BBF612; 11-12-2019 at 08:27 PM.
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Old 11-12-2019, 08:48 PM   #11
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Default Re: Calculating dual quad cfm requirement

620 lbs:


A-460 block, Crower/SVO 4.25" steel crank, A-460 heads and intake
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Old 11-12-2019, 09:10 PM   #12
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Default Re: Calculating dual quad cfm requirement

.

I could never get a straight answer, so on a 850 HP engine, we ran dual 1050's and it was better than anyone could have predicted!!!

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Old 11-12-2019, 09:19 PM   #13
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Default Re: Calculating dual quad cfm requirement

Jon Kasse used two 1250's on his 800 hp MEL EMC winning engine and two 1200 Demons on his 1100hp 537 bbc EMC engine, I'm sure it's all about the signal to the boosters/ect.
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Old 11-15-2019, 11:27 AM   #14
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Default Re: Calculating dual quad cfm requirement

Quote:
Originally Posted by fmerkl View Post
put 2 1150 Domi's on it and it will work
Frank
Quote:
Originally Posted by 2 wicked View Post
Thanks for the info, I did find a cfm calc for multi carb setup and it suggested 1133 cfm range. The A460 heads from TEA are flowed on a 4.6 bore and spec [email protected] lift int and [email protected] lift. If I remember correctly, when I called them. We have a gen 3 1150 on current setup. Just have to buy another. Thanks again cory
The math says that should be around 0.4 in Hg manifold vac at WOT with 557 cubes, 7500 RPM, and 100% VE.
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there is nothing in an LS that will support more hp per CID than a Gen 1... absolutely zero.
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Old 11-18-2019, 12:07 PM   #15
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Default Re: Calculating dual quad cfm requirement

With mud and a 557 at 7500 max keep it no bigger than 1050's. And probably with small skirts.
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