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intake manifold design
#771473
08/11/10 02:15 PM
08/11/10 02:15 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
OP
Senior Management
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OP
Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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It's been a while since I read Corky's book so I don't remember all the ins and outs of EFI manifold designs.
Fred has a tunnel ram and plenum design for his monster motor. Most guys use a typical 4 bbl intake with a throttle body. Others use a round throttle body on a 90* neck for a carbed style intake.
How do you determine the best manifold for your EFI engine? I know the long runner intakes are popular on the late model engines but what size plenum are they using?
My intake is a Weiand tunnel ram with a 390 cubic inch plenum on top. Is that better suited to street use, track use, or what?
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: intake manifold design
[Re: feets]
#771480
08/12/10 10:46 AM
08/12/10 10:46 AM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
going to make something Feets?
I already have:
My mind is just wandering a little. A
n idle mind is a dangerous thing.
looks like that started life as a tunnel ram.
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Re: intake manifold design
[Re: furious70]
#771484
08/12/10 06:44 PM
08/12/10 06:44 PM
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Joined: Sep 2003
Posts: 2,175
Duloc
The Shadow
top fuel
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top fuel
Joined: Sep 2003
Posts: 2,175
Duloc
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I believe your reading into this too much if it's for a boosted application.  Just look a roots manifold.
Last edited by The Stig Jr; 08/12/10 07:03 PM.
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Re: intake manifold design
[Re: feets]
#771486
08/13/10 10:25 AM
08/13/10 10:25 AM
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Joined: Feb 2004
Posts: 1,417
Chicago, IL
blownEFI
pro stock
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pro stock
Joined: Feb 2004
Posts: 1,417
Chicago, IL
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Street car vs. Race car makes a difference. Force inducted race car doesn't care too much about intake design as has already been stated in this thread. However, a street car is not on boost 99% of the time and therefore behaves the same as naturually aspirated, so manifold design will have an affect on driveability. If you only care about WOT HP on boost then slap on any ole thing you want and it will probably function.
"These go to eleven", Nigel Tufnel
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Re: intake manifold design
[Re: blownEFI]
#771489
08/13/10 07:30 PM
08/13/10 07:30 PM
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Joined: Sep 2003
Posts: 2,175
Duloc
The Shadow
top fuel
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top fuel
Joined: Sep 2003
Posts: 2,175
Duloc
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Quote:
Street car vs. Race car makes a difference. Force inducted race car doesn't care too much about intake design as has already been stated in this thread. However, a street car is not on boost 99% of the time and therefore behaves the same as naturually aspirated, so manifold design will have an affect on driveability. If you only care about WOT HP on boost then slap on any ole thing you want and it will probably function.
I really can't agree on this theory
The car will drive around just fine with efi as it's tuned with the map/fuel. It might not be optimal but it works.
I would think converting a single 4 manifold over a tunnel ram proves my point. With the unequal runner length and usual poor fuel/air distribution characteristics and issues they still work.
An equal length runner intake should blow it out of the water but the don't seem to.
Show me a factory F.I. manifold with unequal runners
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Re: intake manifold design
[Re: The Shadow]
#771490
08/14/10 01:56 AM
08/14/10 01:56 AM
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Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
Show me a factory F.I. manifold with unequal runners
Modern factory boosted efi cars are designed around providing fuel economy and passing emissions standards. They aren't designed with race-only in mind. I would still say that a crappy 4bbl intake is still going to perform lousy on a boosted vehicle if anything just from air/fuel variations from cylinder to cylinder. I think you at least want a reasonable intake.
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Re: intake manifold design
[Re: DaytonaTurbo]
#771491
08/15/10 11:13 AM
08/15/10 11:13 AM
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Joined: Jan 2003
Posts: 3,336
Summit, NJ
whiplash
master
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master
Joined: Jan 2003
Posts: 3,336
Summit, NJ
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another thing to keep in mind is that most of the manifolds we can get our hands on for the older engines are/were/ designed for "wet flow" applications. I would venture to guess even the ones with efi bungs cast in them still were designed with wet flow ideals. For efi, we have to think about dry flow before the injector. You want some turbulence before the injector to start the mixing, and good velocity. But, the problem is, when you throw boosted flow velocities in the mix its tough to get all that, plus good injector targeting with the older intake openings. Just look at a modern engine and how the intake port has injector openings to help direct the flow at the back of the valve. I know on my EFI 383, you can see the clean spot on the opposite side of the intake port (bottom) from where the injector spray is hitting. Most likely at idle low flow conditions. If I could do it again, I woul look at a short tunnel ram with the injectors underneath to try and adjust that angle.
- 67 coronet 4dr, 383/727/GVOD, blown, EFI, daily driver
- 230/238, 114°LSA cam, 1.6 rollers, 9:1 comp, 8 psi boost
- NEW BEST ET - 12.40@110mph...
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Re: intake manifold design
[Re: feets]
#771492
08/16/10 08:30 PM
08/16/10 08:30 PM
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Joined: Dec 2006
Posts: 42
SE PA
Five9Dak
member
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member
Joined: Dec 2006
Posts: 42
SE PA
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I'm going to see how the modman works with a twin screw sitting on top of it. The runners are short fat and have nice radiused (almost bellmouthed) entries right out of the box.
For a max effort centrifugal application a plenum box on top of the modman might be pretty nice. Stree manners would be pretty terrible I bet though.
Last edited by Five9Dak; 08/16/10 08:32 PM.
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