What mechanical fan are you using?

Engines, Exhaust and Fuel Systems

  1. XfbodyX

    XfbodyX Well-Known Member

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    Weather solid/flex or clutch what and why?

    Remember this is about mech. fans not electric. Im asking because I was going through a pile of fans as I need one and ive had one in the nos parts room I thought I was gonna end up selling since I didnt think it was ok for me but I never really looked until today.

    Mopar says its good for 15hp over the old type but to me it sorta just looks like a bit more modern 80s fan.?????? I paid less the $100 long long ago but have seen them for 2x that.

    dscf0147.jpg
     
  2. Opticon77

    Opticon77 Well-Known Member

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    Motortrend Engine Masters season 2 episode 20. Thermal or RPM clutch fan killed 15hp, Flex fans (plastic and metal) killed 20-25hp, and direct drive OE fan killed 30hp on a 350hp Chevy mighty mouse.
     
  3. Oldiron440

    Oldiron440 Well-Known Member

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    That was on an accelerated test I would like to know how close it would have been on the step test.that is where power is measured and an rpm but not accelerating. The dyno stops accelerating the motor at certain rpm intervals and measures power.
     
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  4. Aspen500

    Aspen500 Well-Known Member

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    I'm running a fan of unknown origin with a thermostatic viscous clutch. Probably doesn't really answer your question. Why is, it's the fan blade I've had on the car since 1989 and is most likely the one that came with the engine(?). Clutch is a new aftermarket unit.

    This is a pic from when I was building the car showing the fan I'm using.
    DSCF0005.JPG
     
  5. DCAspen

    DCAspen Well-Known Member

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    Mopar Viscous fan has the same part #'s as my 1980 parts book for a F-Body with Maximum cooling package.
     
  6. Ele115

    Ele115 Well-Known Member

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    7 Blade fan and clutch for AAR Cuda. This looks identical to the 440
     
  7. Master M

    Master M Well-Known Member

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    That is interesting. I saw a video comparing different types of mechanical fans and there was little power loss on any type mechanical fan until 3000+ RPM's.
     
  8. Oldiron440

    Oldiron440 Well-Known Member

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    I saw the same Engine masters, clutch fan was good for 15 + or - hp.
     
  9. ch1ll

    ch1ll Active Member

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    care to share those part numbers?
     
  10. F body Deconstructor Jim

    F body Deconstructor Jim Well-Known Member

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    mopar factory steel flex... works for me on both 360's.
    surprisingly the demon doesnt need a shroud to run cool, even on a 110* day in traffic.

    100_3224.jpg IMG_20180619_152624696_HDR.jpg 100_2778.jpg 100_2775.jpg
     
  11. volare 77

    volare 77 Well-Known Member

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    77 parts book 3462190 5 blade flex blade 20 inch V8
    3462186 7 blade flex blade 20 inch V8
    3870107 is a 18 inch slant six blade in 77
    my question does the 20 incher fit the factory fan shroud on the smaller radiators?? I guess not?
     
    Last edited: May 9, 2019
  12. Aspen500

    Aspen500 Well-Known Member

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    No, it does not.
     
  13. DCAspen

    DCAspen Well-Known Member

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    18" Fan part # is 4140063, fan clutch part # is 4095853 from 1980 parts book same as Direct Connection viscious fan package
     
  14. AJ/FormS

    AJ/FormS Well-Known Member

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    Everytime I hear those power numbers I cringe.
    Firstly, those numbers were on a full pull. So if you drive around at peak horsepower all the time, I guess you might need those 15 horsepower.
    But most of us don't do that. And if your fan sucked 15 hp at idle, well that's just crazy, no manufacturer would ever have installed a direct-drive fan.
    But driving the fan is also not linear. If it takes 15 hp at 5500, that does not mean it sucks half as much at half rpm.
    And third, Most of us put a thermostatic clutch on the fan, so it automatically cuts out and freewheels at the sensor's cut-out position..... costing you ZERO hp.
    Now here comes the important part;
    Ram air takes over at about 30/35 mph..... so the fan with a T-clutch is no longer active, again costing you zero hp. On the street, most of your time will be spent over 30 and less than 65mpg, so most of the time, the fan will be doing nothing but freewheeling.
    And if you nail the gas at 30 which most of us do mostly, and quit at 65, you will have been at WOT for about 3 seconds or less, and the heat of that episode may not get into the T-clutch until you are long ago off the gas! So it cost you Zero horsepower!
    Think about it.
    Your street engine will be the most-sensitive in traffic at low speeds and with the engine at low rpm.Under this condition, she deserves the biggest, most number of blades, all-steel, fan you can find; installed on a Thermostatic clutch.... not a viscous clutch.
    Sell that 5-blader/ viscous.
    Then get you a 7blade and a T-clutch, and a HD WP with a big shaft and an anti-cavitation plate, and you are all set. You can kiss your overheating blues goodbye. And maybe, if your exhaust is quiet enough, you just might catch that T-clutch cycling, doing it's job ...... automatically. But you better be alert, cuz with a 7-blade it only runs for a short period of time. See if you can notice the engine slow down when it kicks in.
    Forget that HR fan test, it does not apply to a streeter. That had to be an advertising promo.
    End rant
     
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  15. AJ/FormS

    AJ/FormS Well-Known Member

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    Take a good look; I think I see a thermostatic spring on the front there. That's the best set-up.
    A hot-rodder might not need the best , it depends on the combo, the use, the rest of the powertrain, But if you want or need the best this is it; 7 blades, all steel, and the T-clutch
     
    Last edited: May 9, 2019
  16. Aspen500

    Aspen500 Well-Known Member

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    Yes, that is a thermostatic spring on the clutch. Pretty sure I got the clutch from Rock Auto (or it could have been Summit) to replace the OEM one I had on the car previously. It was shot and loose. Basically was free wheeling all the time.
    Must work, the only time the temp gauge ever gets to half scale (stock gauge) is if it's 90 degrees, the A/C is on MAX and I'm going up the VERY steep hill (35 mph speed limit) on Foxglove Road, on the way home from work.