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  1. #1
    Join Date
    May 2013
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    3,669

    Default Air Flow guys , need input

    So I'm going to EFI, will be running 540cid F1c Procharger and a 370ish intake cfm heads, boost will be low 6 to no more than 10lbs. I'm driving myself crazy over the intake I've decided to use the SPX as I have it already, it's a 4150 flange, but with the larger Blowers and big cid 4500 flange desired, no real big deal as I can open the plenum exposing the runner walls which would then be knifedged etc . Or would leaving it somewhat 4150 size maybe open it 1/4in around and do the same to the 4500/4150 adapter and put a "neck" in the plenum with the larger 4500 opening on top blending down into a slightly larger 4150 opening of the intake? Would that promote velocity? In my mind it would, or would it be a restriction?
    70 stage 1 Back under construction
    540 Tomahawk, F1c-94 Procharger
    Holley HP EFI, Stage 2 TE's
    Shooting for 1khp at the tire and 5.50s

    .

  2. #2
    Join Date
    May 2013
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    3,669

    Default Re: Air Flow guys , need input

    Keep in mind if was ran 4150 side up, the shelf would be gone because the plenum would machined open,
    Attached Images Attached Images
    70 stage 1 Back under construction
    540 Tomahawk, F1c-94 Procharger
    Holley HP EFI, Stage 2 TE's
    Shooting for 1khp at the tire and 5.50s

    .

  3. #3
    Join Date
    Feb 2002
    Location
    Pine City, MN
    Posts
    9,654

    Default Re: Air Flow guys , need input

    I assume your running an elbow and forward facing TB? Or is this a blow thru?


    I am building the 4500 flange SPX/Wilson Elbow/105MM TB right now, and it's a whole bunch of machining and handwork. This 555 will run 15-20 psi, and has nearly 400 cfm cylinder heads on it.

    JW
    Owner/operator

    Tri-Shield Performance
    Jim Weise
    Founder/Owner
    V-8 Buick.com
    320-629-8999

    Most folks are about as happy as they make up their minds to be.
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  4. #4
    Join Date
    May 2013
    Posts
    3,669

    Default Re: Air Flow guys , need input

    Yea forward facing monoblade
    70 stage 1 Back under construction
    540 Tomahawk, F1c-94 Procharger
    Holley HP EFI, Stage 2 TE's
    Shooting for 1khp at the tire and 5.50s

    .

  5. #5
    Join Date
    Nov 2013
    Posts
    1,584

    Default Re: Air Flow guys , need input

    Knife edging can be bad for runner distribution/airflow reasons.
    It can force the air to sheer and change direction with the pulses and direction changes in a manifold, whereas a bullnosed front doesn't fall victim to the 'vena contracta' effect.
    I think people with the right equipment, etc. may still do that due to trying to carve out more CSA than practical in the casting.

  6. #6
    Join Date
    Nov 2006
    Location
    ivyland p.a
    Posts
    1,603

    Default Re: Air Flow guys , need input

    Wilson Did this Intake . Stage 4 Heads

    I will post a better pic if you want
    Attached Images Attached Images
    1969 gs 400 convt 455 11.42@117mph current12.50
    1969stage 1 convt all #s. 13.88@99
    1969gs/skylark clone 4spd (sold)
    1969skylark racecar stage 4 heads
    1969gs convt 4spd (sold)
    1970 stage 1 all #s 4 spd sherwood green
    1970 stage 1 burgundy mist #s Auto 13.44@101
    1970 stage 1 dipolmat blue #s Auto to 4 spd
    1971 stage 1 cortez gold #s 4spd
    1969 stage 1 with Iron Stage 2 heads 455cid 4:78 & 2x4 holleys, M 22 Vertex-Ronco Magneto, Kenne bell parts 595hp

  7. #7
    Join Date
    May 2013
    Posts
    3,669

    Default Re: Air Flow guys , need input

    Thanks for the pics Nick, definitely provides some idea and direction
    70 stage 1 Back under construction
    540 Tomahawk, F1c-94 Procharger
    Holley HP EFI, Stage 2 TE's
    Shooting for 1khp at the tire and 5.50s

    .

  8. #8
    Join Date
    Sep 2014
    Posts
    68

    Default Re: Air Flow guys , need input

    Set it up to be a Venturi shaped as best you can.
    a tad smaller in overall volume can more than be over come with a mere 1.5 psi more in boost!
    The Venturi will give much better fuel distribution!
    The radius leading ino the top of each runner should be as close as you can get it to the radius of the top of a runner left to right wise, or even softer.

  9. #9
    Join Date
    Apr 2002
    Location
    Arlington, Texas
    Posts
    674

    Default Re: Air Flow guys , need input

    Ethan,

    With a Tomahawk build like yours I am surprised you don't just sell your 4150 SPX and get a new 4500 manifold. In the grand scheme of an EFI S/C Tomahawk build the difference is not worth worring about. Just food for thought.

    Good luck with your build!!!

    Jim
    Jim Byers
    65 Skylark

  10. #10
    Join Date
    May 2013
    Posts
    3,669

    Default Re: Air Flow guys , need input

    I guess I'm more after distribution quality , HP will be there in abundance, no matter how i go about it, just want to keep all the holes burning good, Its one of those things you won't know till you try I guess,...just don't want it to be a very expensive lesson ha
    70 stage 1 Back under construction
    540 Tomahawk, F1c-94 Procharger
    Holley HP EFI, Stage 2 TE's
    Shooting for 1khp at the tire and 5.50s

    .

  11. #11
    Join Date
    Nov 2013
    Posts
    1,584

    Default Re: Air Flow guys , need input

    Might be tough to do on the bench before any testing.
    I'm thinking you'll want to spend some time with your head and intake on a flow bench, maybe shoot some ink down the manifold.
    Creep up on your tune on the dyno, using a temp gun aimed at the exhaust port or temp probes.
    I know, obvious...

 

 

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