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quick question about electric fans

Discussion in 'Chit-Chat' started by chuglife, Jul 2, 2005.

  1. chuglife

    chuglife

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    not "tech" enough for tech.

    what speed would an electric fan typically run at? for arguments sake, we'll say its a single speed fan from a ford taurus.

    do you think an electric fan would move more air than a mechanical fan on, say, a toyota mini-truck?

    now, let's say you kept the mechanical fan and mounted an electrical fan in front of your rad... this would work VERY well, would it not? is it more efficient to "push" or to "pull" the air through the rad?

    thanks in advance :grinpimp:
     
  2. Rich

    Rich

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    Fan pulling is more efficient than fan pushing. No automotive electric fan moves as much air as a high volume mechanical fan. Electric pusher in front of mechanical would help during low speed low rpm operations, I.E. rock crawling. I don't know, but would guess, that at highway speeds, an electric pusher fan just gets in the way and probably reduces total airflow.
     
  3. sisukid1975

    sisukid1975

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    electric fans are preferable. tractor drive (pulls air thru the radiator) is generally better. The type that push are through are usually used for AC Condensors.

    When you're at speed, the fan doesn't matter much as the airflow over the radiator at driving speed is better then with any fan...

    When you're idling or moving slow the amount of CFM an electric fan moves is greater than most mechanical fans (Especially dual fan setups)

    When you're fording deep water, an electric fan won't get ruined by hydrostatic pressure (if you wire it with a toggle in the cabin) If you can toggle it on, off or auto, you have more control of when it runs, turn it off for deep water, extreme cold weather, or if you know you're going to be getting the engine hot, like towing up a steep grade, turn it on ahead of time. Rest of the time leave it in auto mode. You can set the fan to come on precisely when you want it to, and shut off precisely when you want it to. It can be wired to turn at different speeds at different temperatures.

    Less parasitic drag on the engine = better fuel economy

    Greater replacement interval for the water pump

    Less noise (generally speaking)

    They tend to have more long-term durability than mechanical clutch type fans. (No clutch to replace)

    Fred
     
  4. Rich

    Rich

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    How much cooling is needed is a significant factor. If more cooling is needed than an electric fan can provide, then mechanical is the only choice. My Fzj80 runs hot. Don't think an electric fan would be best choice for me. I think for offroad a pusher auxillary would be a good addition for my cruiser.
     
  5. chuglife

    chuglife

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    thanks for your help guys :cheers:
     
  6. T Y L E R

    T Y L E R

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    All tech aside : Just remember to keep those darn clothes dryer venting tubes hooked up tight !!! :D





    hehe .. Can still see you on the trail .. perplexed, as I look in and spot 'da big tube hangin on the floor; disconneted.


    Chels - "Damn , it just won't defrost in here .. "




    TY
     
  7. chuglife

    chuglife

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    :mad: ARRRGGHHHH rub it in :frown:


    it was a one time thing ;) in fact, i had only been driving the truck for a couple months, if that. :doh: :doh:
     
  8. miked

    miked

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    i've often wondered about this myself. i would like to see the amount of electrical current draw of the motor at a stand still vs. highway speed.
    i suspect that at highway speed, if the motor is turned off, it would impede air flow even though it would be spinning from the force of the air rushing in through the grill. now if you turned it on, i suspect the current draw would be alot less than at a stand still due to the same force of the air rushing through the grill.

    here in the imperial valley, it gets so hot that my a/c doesn't really get cold until i hit 50+ mph. one reason i think is lack of air flow. the other could be that the transmission's torque converter is making so much heat and dumping it through the tranny cooler, that it heats the condenser. once the converter 'locks' the ATF temp drops off rapidly.

    i've been thinking of adding an electric pusher fan but don't want to shorten the life of my alternator by adding a large, always on load. sure, i'll put a switch on it but i've been known to forget about turning these types of things off on past vehicles.
     
  9. T Y L E R

    T Y L E R

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    Don't feel bad Chels. You were just tryin to make the out-of-town-tech-challenged-guy-from-Ontario feel like he belonged .. :D


    Totally worked too !! ;p


    Peace,


    TY


    PS : And quit changin my font colour .. thought my monitor was set to gay again .. :ban:
     
  10. Rich

    Rich

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    Mike,

    Regarding control of aux fan to improve AC performance: you can buy controllers that will automatically switch the fan on and off at set coolant temps. You can also wire the fan to automatically come on when the AC clutch is engaged.

    For the non US 80s with dual ac Toyota installed an additional pressure switch in the high side refrigerant line after the condenser which controlled the activation of the condenser fan.
     
  11. miked

    miked

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    i am definitly going to look into adding a fan. maybe with just a toggle switch/relay to keep it simple and cheap for now but i like the idea of an auto switch.
    are there any fans to watch out for would you think the ones from autozone and the like will do.
     
  12. Rich

    Rich

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    I can't say which are good and which are not. Given the limited area to install a pusher (vertical grill support and trans cooler occupy half of the space) I wouldn't think that there will be a whole lot of choice of what will fit.

    Rough measurement shows more or less about 12" x 12" outer dimension might fit. Depth available looks to be around 3".

    Here are some of the websites I have looked at:

    http://www.flex-a-lite.com/
    http://www.derale.com/electricfans.shtml
    http://www.haydenauto.com

    You would need to start by measuring the free space in front the condenser not occupied by tranny cooler. You may want to relocate the horns to free up a little more space.
     
  13. miked

    miked

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    thanks Rich

    does anyone know or have a guess at what the average CFM of a stock clutch fan is? i know there are many variables and we seem to be on the fringe of real aerodynamic science but... lets say ball park figures?
    i'm asking because it would seem that if you took the CFM of the stock clutch fan and the CFM of an electric pusher, the total CFM of the system wouldn't be the sum of the two. i'm looking at some impressive CFM numbers from the sites Rich has linked but, i wonder if i need that much while keeping the stock clutch fan.
    er...