CFM Per HP

Posted by jsicfy, Sep 14, 2004
Bolt-on Tech - 4G63 intake, exhaust, intake manifold, ignition, fuel system, cooling, etc.

  1. jsicfy

    jsicfy Proven Member

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    fort collins, Colorado
    Does any one here know a mathmatical formula to convert the cfm flow of somthing into how much HP it will support? Like if it were to flow 600 cfm and support 600 hp.
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  2. zross1

    zross1 Proven Member

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    That's a good question. Sorry I don't know the answer. Hopefully someone does :)
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  3. 95GSXracer

    95GSXracer DSM Wiseman

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    Central, Massachusetts
    Unfortunately, CFM is meaningless unless it is standardized. You need to know the mass of the air, since that determines the mass/weight of the fuel you can burn (air:fuel is a mass/weight ratio). Thats why it drives me nuts when turbos or compressor maps are rated in CFM. If you can find out in Lbs/min (which is becoming much more popular thee days) you can get an idea. As a general rule of thumb, every lb/min of air is good for 10 HP. Now, several factors affect this, mainly how efficiently you use that air. AFR, timing advance, etc. Its fairly accurate on well tuned cars.

    Edit> If you know the temperature and pressure, you can convert CFM to lbs/min by the way. The formulas are out there on the internet I'm sure.
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  4. jsicfy

    jsicfy Proven Member

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    fort collins, Colorado
    I found that an average 1.5 cfm is flowen for every 1 HP
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  5. loreak

    loreak Proven Member

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    divide cfm by 14.7 and that is lb/min
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  6. kpt4321

    kpt4321 Proven Member

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    I hope you're joking....

    Like he said, you need temperature and pressure to convert.
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  7. gasguzzler

    gasguzzler Proven Member

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    Escanaba, Michigan
    To get you into the ballpark (engine efficiency and temps have an influence also), but take CFM x .069 = estimated lbs./min
    lbs./min x 10 = estimated HP
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  8. 1fast97gsx

    1fast97gsx Proven Member

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    Orland Park, Illinois
    I think you are talking about converting from bar to psi .... 1 bar = 14.7 psi.
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  9. doug

    doug Proven Member

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    , SoFla
    There was a thread a while back on here about it:
    http://www.dsmtuners.com/forums/showthread.php?t=20184
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  10. kpt4321

    kpt4321 Proven Member

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    There is some great information in that thread, thanks doug! Good job setting this up for the archives and such!
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