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Are Flex-Fans any good?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Bowtied, May 24, 2001.

  1. Bowtied

    Bowtied Registered Member

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    I was cosidering installing a Flex-fan for several reasons but I thought I'd check with the online-gurus first. The ads say better fuel economy etc.......

    Any good or bad words about them?
    Do they help gas mileage and do they keep things cool?

    Thanks a lot for the info.

    Bowtied
     
  2. J.R.

    J.R. Guest

    i like mine, have always used them. just give them plenty of room to work, depending on the fan some expand with rpm.

    BIGBLOCK MAN
    bigger is better!
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Actually, I believe that flex fans actually DECREASE performance and mileage due to the fact that they are always "engaged". The higher the RPMs, the more power the fan robs from the motor.They can also cause your motor to take longer to warm up. With a clutch fan, the fan only comes on when it's needed.

    One good thing about a flex fan is that it's always pulling air through the rad, regardless of the temp of the engine bay. They are also cheaper than the clutch assembly.



    <font color=red>PHOTO ALBUM-</font color=red> <A target="_blank" HREF=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</A>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  4. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    I've had one for several years and about the only good thing I've noticed is the noise they make. :O) Didn't decrease or increase gas mileage, when you're wrenching around one you have to be careful cause one little slip and you're bleeding like a stuck pig.

    "Liberals ain't mean, they just don't have any common sense!"
     
  5. Bowtied

    Bowtied Registered Member

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    That leads me to one more Question. Could / should you use it with the clutch? I would assume without. Is this correct?
     
  6. J.R.

    J.R. Guest

    all i know is that they have worked for me, and on the dyno the clutch fan takes more power to run then the flex fan. as far as nosie, i havent noticed any at all. it does help my big block to run cooler, which is a good thing! but it's to each his own, we all have had good and bad luck with different products.

    BIG BLOCK MAN
    "MORE POWER"!!
     
  7. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I'm almost positive that you run flex fans without the clutch. In fact, I don't think that a flexer even has the adaptor holes to accomodate a clutch even if you tried.............

    JR- That's interesting abou the dyno thing. I guess I might be wrong about the horsepower loss. I do know from experience that you can hear a pretty good roar from a flex fan when you wind the motor up, but that may depend on what brand you buy and how deep that sucker sits in your shroud...........





    <font color=red>PHOTO ALBUM-</font color=red> <A target="_blank" HREF=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</A>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  8. Bowtied

    Bowtied Registered Member

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    Thanx,
    If the dyno likes it and it still keeps the engine cool then I'm sold. Do you recomend any particular brand or are they all about the same?
     
  9. WOODYJ

    WOODYJ 1/2 ton status

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    I have been running flex fans on and off for many years. You have an up side and a down side to a flex fan. Flex fans sound like you are taking off in a jet or something---Very Noisy! I have used fiberglass and steel both and you can't hear yourself think if you are running a large one. I haven't seen any that ran on a clutch. All the ones I have run across have been direct drive off of the water pump. The up side is that the big fans seem to move allot more air than the fan clutch fans. I ran a turbo for many years and a fan clutch type fan would not keep the engine cool as well as a large flex fan. Just sharing a little experience. Many people might have better luck than I had. I always wanted the biggest fan that would fit in my shroud. I have seen allot of people running smaller ones. They might not be so loud. All I know is when you hit the gas it sounded like you just kicked in the afterburners.


    k5woody I Don't Understand The Jeep Thing Either!!!
     
  10. Pugsley

    Pugsley 1/2 ton status

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    Far as I know, there is no way to operate a flex fan with a clutch. I personally have never had good luck with them, but I know alot of guys/gals that swear by them.

    I have voluntarily axed "Pancho" in a bandwidth conservation effort [​IMG]
     
  11. wayne

    wayne 3/4 ton status

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    No you do not run a flex fan with a clutch. What a flex fan does is flatten out as rpm's increase, tharefore creating less drag. Just make sure to get one with big blades that will pull alot of cfm's.

    <A target="_blank" HREF=http://jamonline.homestead.com/fromthegroundupK54x4/89Jimmy.html>http://jamonline.homestead.com/fromthegroundupK54x4/89Jimmy.html</A>
    <font color=blue>Happy Trails<font color=blue>
    <font color=blue>Wayne<font color=blue>
     
  12. DMK

    DMK 1/2 ton status

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    Have one on my 66GP. Did'nt notice any more noise.
     
  13. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Here is a recent post discussing the other options:
    <A target="_blank" HREF=http://www.coloradok5.com/forums/showflat.pl?Cat=&Board=blazer4x4&Number=137792&page=&view=&sb=&vc=1>http://www.coloradok5.com/forums/showflat.pl?Cat=&Board=blazer4x4&Number=137792&page=&view=&sb=&vc=1</A>
     
  14. muddin4fun

    muddin4fun 3/4 ton status

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    I have one. Yes their noisy, but not bad. They almost sound like a super charger. LOL! What Wayne said is true. The fan flexes so you're not always pulling the same amount of air when ideling. My truck warms up just fine. It takes about 10 minutes for it to get over waking up in the mornings. LOL! The thing that's worth it to me, is I don't have to worry about the clutch going out. I like reliable trucks. I love the flex fan. I've put one on just about everything I own. And they come in colors too! [​IMG]



    <font color=orange>hAS ANYONE SEEN MY cAPSLOCK KEY?</font color=orange>


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  15. J.R.

    J.R. Guest

    i run a stainless steel 10,000 rpm flex fan. dont let the rpm rating scare you. what it does is as your engine rpms increase the blades flatten. it is made for trucks for towing and performance. i have mine set deep in the shroud about 1-11/2 inches frome the rad. this sucker pulls air through there like you cant believe. if i hold a heavy shop towel in front of the radiator it will suck it to it! and you dont use a clutch with it! that is why it take less horse power for a flex fan than the stock unit. i got mine from jegs, its about $35 and then a few bucks for a fan spacer to get it closer to the radiator.

    BIG BLOCK MAN
    "MORE POWER"!!
     
  16. Jason73K5

    Jason73K5 1/2 ton status

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    I personally don't like flex fans. They just don't seem to provide any better cooling that stock fans, plus they're always drawing power. I'd either stick with stock fans or go electric. Electric are my favorite because you can have control of when the fan comes on as well as having a thermostat control. If you ever do water crossings, electric is the way to go unless you want to remove your fanbelt before you cross, otherwise you'll buy yourself a new radiator. If you do get a flex fan, do yourself a favor and debur all the edges on the blades. These come VERY sharp and won't hesitate to slice your flesh, even with the engine off.
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    The loss of "power" as dyno tested from a flex fan is pretty consistently shown to be 5hp. Of course that depends on motor output in the first place, etc. The major difference would be the weight between the two units, the flex fan of course being lighter. Remove the jack, same fuel economy benefits.

    Flex fans would be good for idling and low speed use, but no better than a clutched fan with the same size/blade pitch. It is physically impossible for a flex fan with the same blade/pitch as a stock thermal/clutch fan, to work any better, since when locked (at the correct engine operating temp) the clutch fan is turning just as fast as the motor. Along with this, since stock clutch fans are "set" from the factory to keep the engine in its optimal operating range (195 to about 210 or so) if you are trying to keep your motor under that temp (which is not a good idea anyway) the stock fan would NOT be effective, as it would never lock up.

    As well, at high RPM's, flex fans are costing you HP due to design, and inhibiting cooling. If you think not, explain how a fan that is no longer turning (a stock fan at the proper operating temp) somehow uses more power than the flex fan, which has no ability to stop turning, thus creating drag because of its nature as a fan, trying to move air.

    Its a wonderful feature that the flex blades flatten out at higher RPM, works great as an air dam at freeway speeds to keep air from getting through your radiator and working the way it is supposed to. Cover the back of your radiator with cardboard and see if it runs cooler or hotter. Exactly what a flex fan does at higher speeds.

    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     
  18. Itali83

    Itali83 1/2 ton status

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    I got a flex fan and it is very loud!!! when I get on it. I don't have any cooling problems, even at highway speeds, but I would like to see what the factory clutch/fan would do. I like the idea of getting a few more H.P. out of the deal too. If I do acually change to factory set up. I'll tell you guys how I like it.
    Ben 87 Jimmy
    <A target="_blank" HREF=http://www.bens87toy.coloradok5.com>http://www.bens87toy.coloradok5.com</A>
     
  19. ragtop

    ragtop Registered Member

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    I'm a solid believer in large (19") flex fans for max cooling! Tried most everything on my '81 Camaro w/ 454 from steepest pitch clutch fan w/ HD clutch, GS "Tornado" electric and Dual Perma-Cool High Perf 14" electrics and nothing would allow me to sit in heavy traffic, on a 90 degree day, with the A/C on high, and keep the temp guage at 180, but the flex fan came the closest, though it is noisy. Gone thru similar tries on my K5, though it only has the stock 350, the temp guage tried to climb to above 210 in stop and go traffic, or when pulling the boat uphill on hot days. Along with a new copper brass radiator (aluminum was more $ than I wanted to play on cooling with right now)and high flow 180 deg thermostat, I'm currently running a 19" flex-a-lite flex fan w/2" spacer (leaves about 1 1/2 " of fan sticking out the rear of the shroud) and a single 14" Perma-Cool high perf electric (attached with the thru the radiator wire tie things) inside the shroud, between the flex fan and the radiator) with a thermostat control w/AC overide (on all the time if A/C compressor is engaged). This combo seems to be doing the job as the K5 mostly runs at 180 deg. (about a needle's width below the mark between 100 and 210, and the same place it runs on the coldest days of winter), and has only made it up to that center mark (between 100 and 210) when I'm in stop and go traffic or pulling the boat uphill on high 80's days. I'm still waiting for the 90's this summer for the final test! To each his own, and I know that max power is achieved at a higher engine temp, but my goal is to run the thing as cool as I can for longivity, and with a big trans cooler and engine oil cooler in front of the A/C condenser, along with the desire to run the A/C on high most of the time (I'm hot natured), keeping the engine from going above 180 has been a real challenge.

    '88K5 - 350TBI, 700R4, 208, 3.42 10 bolts w/Auburns & 31s
    Ragtop - [​IMG]
     
  20. Bowtied

    Bowtied Registered Member

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    That's funny, you've tried everything I've thought about trying, except for the setup with both behind the rad( that's interesting).
    And you ended up with the flex fan. I'm thinking at this point that I will be going with the flex a lite. Pretty much for the same reason as you, keeping the engine cool no matter what the situation.

    Thanks for the info,
    Bowtied
     

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