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Fresh Air Intake Idea - What do you think?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 502Burban, Nov 22, 2001.

  1. 502Burban

    502Burban 1/2 ton status

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    I've just purchased a Vintage Air A/C unit for my Suburban, and it eliminates the fresh air intake for the A/C unit by blocking off the hole in the passenger side kick panel. This has given me an idea for the fresh air intake for the engine and I want to know if there are any flaws in my plan.

    What I'm thinking is that I could use the cowl air box area to feed my engine a supply of high-pressure cool air from the cowl area. What I would do is use the 4.5" diameter hole in the cowl, where the heater fan normally is, to run 4" ducting to my airbox to feed the fuel injection.

    The air would come through the plastic cowl screen and be nice and high, away from any water problems that could be a problem with an intake feed from the radiator core support area that I was originally planning to use. Also, on rainy days, any water that gets in the system would easily drain out the bottom of the cowl box, keeping the intake system dry.

    Does anyone see any flaws in this plan?

    Do you think I would be able to draw enough air to feed the big-block?

    Please feel free to poke holes in my idea. I really respect the collective knowledge on this board and know that if there are any problems with my design, you guys (and gals) will find them.[​IMG]

    Thanks,

    Robb
    '73 GMC Suburban - 502DFI
    <a target="_blank" href=http://community.webshots.com/user/robbrj>community.webshots.com/user/robbrj</a>
     
  2. newyorkin

    newyorkin 1 ton status

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    That sounds like a really cool idea to me! I'd figure water would get sucked in anyway though, while the engine's running. Also, I might think at high speed, the engine would have to suck a little harder to get air that would be flowing up the windshield away from the cowl, as opposed to getting a little help from air flowing into the grille. I really have no idea, though... That's all I can come up with for holes to poke... otherwise it sounds like a great idea to me.

    Ratch
    <a target="_blank" href=http://k5.8m.com>k5.8m.com</a>
    Welcome to America.
     
  3. BLUESMAN

    BLUESMAN 1/2 ton status

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    I am planning the same sort of set up.A 16" by 20" air box(out of alum.) by 5" tall and install a 14" by 5" tall K&amp;N filter.I would have one 3" duct going to the cowl...where all the air would be sucked from.This would be away from the engine heat and would be fresh air thru the cowl/hood area.I was going to do the stock set up thru the radiator support but it would allow water to come in even faster.I'll see what I come up with and how it works soon.
     
  4. Twiz

    Twiz 1/2 ton status

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    Sounds like a cool idea o me. I wouln't think there would be a problem with it pulling in water. (if your talking about the same 4.5 hole I'm thinking of) It's off to the side, not directly below the cowl vent, that should help keep the water out of it.

    The base of the windshield is a high-pressure zone. As the air flow slams into the windshield and is forced over it, it creates a high pressure area right at the base, where the hood and the windshield meet.

    Ram air is not very efficiant unless the throttle is Wide Open and the vehical speeds are more than 70 mph. But cold air induction is very helpfull as long as the air flow is not turbulent and the A/F ratio is corrorected for the cooler/denser air charge.

    <font color=blue>Twiz
     
  5. 502Burban

    502Burban 1/2 ton status

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    Thanks for the responses, guys.

    Twiz, do you think that it will be able to pull enough air? This is my biggest concern, as the back of the hood actually rides over the plastic screen at the top of the grill, and I'm afraid that it may not allow it to breathe well.

    I do like that it will provide a large still air supply to pull from, but just not sure about the total flow capacity.

    Thanks again,

    Robb
    '73 GMC Suburban - 502DFI
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  6. Twiz

    Twiz 1/2 ton status

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    I would think It would flow plenty. Not only would it be -slighly- higher than standerd air pressure, but also cooler and denser (more air, per cubic-foot). The square footage of the cowl is way-more than what I would think would be needed by the engine.

    And just how much time do you spend at WOT and 5-grand? (max air demand)

    Ever drive a old car with "push-pull" vents, the air that is pushed in to the intirrior is from the cowl and the cowl is vented to the rockers (for H20 drain) so yo really only feel half of the air-presure avalible. (in therory)

    <font color=blue>Twiz</font color=blue>

    Come to think about it, I think the stock 8.1L have about 3" ducting, just guesing at the measurements.<P ID="edit"><FONT class="small">Edited by Twiztid on 11/23/01 08:32 PM.</FONT></P>
     
  7. 502Burban

    502Burban 1/2 ton status

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    Thanks, Twiz! I figured that it would work just fine, but it's always nice to do a quick gut-check just to make sure that I haven't missed something stupid. Sounds like I'm going to go with it.

    Take care,

    Robb
    '73 GMC Suburban - 502DFI
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  8. Twiz

    Twiz 1/2 ton status

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    Pics dude, pics...

    <font color=blue>Twiz
     

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