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Thread: cfm question

  1. #1
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    Default cfm question

    hey guys, I'm planning on building a custom fan shroud and dual electric fans. Planning on doing this build over the next couple of months. Anyways, my question is how much cfm do you think my 03 silverado z71 5.3l needs. The fans I'm looking at are 14" and rated at 2000 cfm each, putting it at 4000 total. Think that's enough?
    TIA
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  2. #2
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    If you've got 14 inchers that pull 2,000 cfm that's excellent. That's equal to Flex-A-Lites 16" S blade fan. Good you're building your own fan shroud. Cover the entire core (something not all aftermarket manufacturers do) & make it so your fans are as far back from the rad as possible so they can pull the air more evenly over a larger area.
    Last edited by stephan; 08-03-2011 at 07:48 PM.
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  3. #3
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    thanks. ive figured the dimensions to be 17 1/2" tall and 28" wide. covers the core perfectly(completely). but, because of the width, no matter how i would lay out the fans on this surface the fans would both be rite on the edges and touching each other. my fix is 1 - 14" 2000 cfm fan and 1 - 12" 1500 cfm fan. fans wont be on the edges and not touching each other either. i figured about an inch gap between the fans and radiator should be plenty. thats all aftermarket swaps will give you anyways.

    ---------- Post added at 07:35 PM ---------- Previous post was at 07:28 PM ----------

    http://www.store.procompelectronics....oduct_id=36840
    12" fan

    http://www.store.procompelectronics....oduct_id=36841
    14" fan

    these are the fans i was looking at getting. amazon shows a little different specs than the manufacture website

  4. #4
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    That's the same problem I had with the 2 fans not fitting within the width of the core, so I built my shroud with an angle at the rear. Difficult to explain, but the middle rear of the shroud comes to an angle & is farther removed from the rad than the sides are, giving me more room for the bigger fans.

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    that sounds like a great idea. makes it a little more difficult, but not something i cant work out...which fans did you use?

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    I went out & measured everything just to make sure I'm giving you correct info. The fans are 14", but are not the S blades. They're just the generic straight blades that they've been using for years. Don't remember the brand name cuz they're 9 or 10 years old & the labels fell off.
    When I'm standing at the front of the truck & looking down on the top of the shroud it looks just like the pitched roof of a house. The distance from the rad core to the rear angle is 6" & the bottom is exactly the same. The distance on the sides from the core back to where I made my bends is 2" This makes a lot of room inside the shroud so the fans are pulling air from over the entire core, not just in 2 small localized areas. Having it angled also gives more area on the sides to mount the fans because as you're angling the shroud to the rear you are also increasing distance, so there's plenty of room to use 2 - 14"s I think I might have even been able to squeeze 2- 16"s in there. A larger space inside the shroud & a reasonably large distance from the rad is key to getting efficient cooling because it gives the fans more draw area. I smoke tested mine & with one fan on, it still pulls large amounts of air through the opposite end of the rad. Even with the angled shroud it still leaves me an inch of space between the back edge/angle of the shroud & the front of the WP pulley, so there's plenty of room to get at the pulley for changing belts or to replace the water pump.
    Last edited by stephan; 08-03-2011 at 09:50 PM.

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    found this, thought it was hilarious
    http://www.kingmotorsports.com/p-305...ling-fans.aspx
    19960 cfm!!!

    ---------- Post added at 09:17 PM ---------- Previous post was at 09:01 PM ----------

    well i found these at a decent price, twice as the others but look much more promissing
    http://www.zirgo.com/catalog/Cooling...lu-Cooling-Fan-

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    19,900 cfm lol, that's gotta be a misprint or smth. I'm having a hard time believing it could even pull 5,000 at that diameter. I think I'll go back there & see if they have a "contact" email so I can ask them.
    I've never heard of Zirgos before? Have you? Have they been around for a while?

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    i never heard of them until yesteray when i was investigating fans. a lot of people said thats what they where going to buy or alrready did. their website says their fans are lifetime warranty

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