Author Topic: Increasing cfm  (Read 4588 times)

Offline Marx3

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Increasing cfm
« on: September 08, 2016, 12:48:25 PM »
A friend of mine, who is an avid racer ( Buick fanatic ) is getting ready to put together a new engine. He always runs Qjets.
We have been talking about setting one up for a wild 455. Think he intends to go into the 10's or maybe lower. Pretty serious.
How can I modify a large cfm unit for this? Is it even necessary?

Offline carmantx

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Re: Increasing cfm
« Reply #1 on: September 08, 2016, 09:15:26 PM »
What's the horsepower?
The Buick quadrajet from 71-74 can be set up for fast Buicks.  10's aren't a problem.
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Offline Marx3

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Re: Increasing cfm
« Reply #2 on: September 09, 2016, 02:35:34 PM »
Not sure about the HP rating yet. I know Cliff supports about 650 horses with a large cfm unit. Dont know if it has been touched in places...:-)

My friend is romanticizing this abit I think. He wants 900+ cfm, just for the heck of it.
I guess it aint even necesary at all...
I wonder at what displacement the large cfm units falls short... or what HP.

Offline carmantx

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Re: Increasing cfm
« Reply #3 on: September 09, 2016, 04:18:23 PM »
I run mine on a 464 in mid 500 hp range and a 462 at about 500.  I built one for a 570 ci.
If I remember right, there was about 3 hp difference on dyno compared to 950.
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Offline 77cruiser

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Re: Increasing cfm
« Reply #4 on: September 09, 2016, 06:04:17 PM »
I run mine on a 464 in mid 500 hp range and a 462 at about 500.  I built one for a 570 ci.
If I remember right, there was about 3 hp difference on dyno compared to 950.
What's the rest of your fuel system tank to pump?
Jim

Offline carmantx

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Re: Increasing cfm
« Reply #5 on: September 09, 2016, 08:49:30 PM »
On the 462, I have 1/2" line from tank to a mechanical pump.
On the 464, fuel cell and braided hose with electric pump and regulator.
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Offline Marx3

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Re: Increasing cfm
« Reply #6 on: September 10, 2016, 02:41:14 AM »
I run mine on a 464 in mid 500 hp range and a 462 at about 500.  I built one for a 570 ci.
If I remember right, there was about 3 hp difference on dyno compared to 950.

3hp difference from a 950 cfm! cool.
Do you remember the air flap opening distance?

Offline carmantx

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Re: Increasing cfm
« Reply #7 on: September 10, 2016, 05:27:39 AM »
1.30" I believe.
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Offline Marx3

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Re: Increasing cfm
« Reply #8 on: September 10, 2016, 09:32:09 AM »
pheew, that sure means open.
I seem to remember, that the flaps can open too much, slowing down the incoming air. Dont remember at what opening distance this happens.

Offline 77cruiser

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Re: Increasing cfm
« Reply #9 on: September 10, 2016, 01:43:46 PM »
Now you got me thinking that I might have mine open too far.
Jim

Offline Marx3

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Re: Increasing cfm
« Reply #10 on: September 11, 2016, 07:55:48 PM »
Haha oh no!
How far does your open?
I thinks it's in the book, even?
Gotta see if I can look up the max distance.

Offline 77cruiser

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Re: Increasing cfm
« Reply #11 on: September 12, 2016, 06:03:28 AM »
I think I have one of them at 1.28.
Jim

Offline von

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Re: Increasing cfm
« Reply #12 on: September 13, 2016, 02:17:11 AM »
What method is used to measure it?

Offline dlong70elcamino

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Re: Increasing cfm
« Reply #13 on: September 15, 2016, 11:16:37 PM »
I've got mine set at the max of 1.270 on a 750 cfm unit on a built 350 Chevy works great its drag raced weekly......Dan

Offline Ethan1

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Re: Increasing cfm
« Reply #14 on: September 16, 2016, 02:05:19 AM »
What method is used to measure it?

 Von,
 See if this website helps?

 http://www.mre-books.com/quadrajet/edelbrock.html
Ethan

1972 Chevelle

(oo______oo)