Mechanical Fan or Clutch for bbc serpentine - Team Camaro Tech
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post #1 of 10 (permalink) Old Feb 20th, 12, 02:48 PM Thread Starter
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Michael
 
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Mechanical Fan or Clutch for bbc serpentine

I have a 454 (bb) with a serpentine setup (the gm ones sold through summit for crate engines)and currently have a six blade fan (Flex-a-lite 1517) with a shroud and the summit direct fit aluminum radiator. It cools great, but am i giving up significant power? I bought a 2797 hayden thermal clutch and fan but figured it wouldnt work with the serp setup since its reverse rotation ... Am I good or should I seek out a clutch fan??
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post #2 of 10 (permalink) Old Feb 20th, 12, 03:49 PM
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Re: Mechanical Fan or Clutch for bbc serpentine

The clutch fan set-up will work better and use no power as long as the clutch is not engaged.
If w/pump is reverse rotation, you will need the same reverse rotation fan and clutch.

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post #3 of 10 (permalink) Old Feb 20th, 12, 04:58 PM
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Re: Mechanical Fan or Clutch for bbc serpentine

It would be nice if someone could find hp figures between the two. Flex a Lites will flatten out at speed for less drag hence their name. They look cooler too but Everett is right.
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post #4 of 10 (permalink) Old Feb 20th, 12, 06:57 PM
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Re: Mechanical Fan or Clutch for bbc serpentine

These clutch fans are real old technology....
But so is a cloths peg and it still does the same job the best in the 21 st century.
Working on a late model mercedese today..funny has a clutch fan...
Clutch fans still spin up when disengaged...mind you stream air across those blades at 30 mph and no wonder they still spin.
A flex fan is still being driven...40 yr old boy racer technology with good propaganda ...sry marketing BS that still hangs around to this day...
Really got to hand it to those marketing guys back then, they really earnt ever penny they got.

The 40yr old technologhy of our cooling systems not only work as well as a peg these days, they where way over built and made out of better materials than todays cars.

Make sure the fan has a shroud.

My Spelling is not incorrect...it is creative

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post #5 of 10 (permalink) Old Feb 21st, 12, 08:14 AM
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Re: Mechanical Fan or Clutch for bbc serpentine

My '97 SL600 V12 has a clutch fan (bitch to change though).
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post #6 of 10 (permalink) Old Feb 21st, 12, 12:12 PM
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Re: Mechanical Fan or Clutch for bbc serpentine

Quote:
(bitch to change though).
And how often do u have to do it...maybe the GM ones are also more reliable....300,000 miles and on my 3rd....the 2nd was stuffed along with the engine, cams springs, trans, rear tyres, when the car got stolen (toweed not fire up), and when in secure police lock up they had a 'play'
At least the GM is not difficult.

My Spelling is not incorrect...it is creative

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post #7 of 10 (permalink) Old Feb 21st, 12, 01:01 PM Thread Starter
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Re: Mechanical Fan or Clutch for bbc serpentine

So are flex fans that awful? What changes would I see going to a thermal clutch? Thanks again for the input...
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post #8 of 10 (permalink) Old Feb 21st, 12, 04:16 PM
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Re: Mechanical Fan or Clutch for bbc serpentine

Flex gans are always turning as they do not have a clutch.
It takes power to pull air. Yes, they do flatten as rpm goes up, but they still pulling power.
Clutch fans take power only when engaged whether the clutch is rpm controlled, meaning the higher the rpm, they become disengaged, but always engaged at lower rpms, or thermal controlled - have a bimetal spring in the front, and engage when the ambient temperature through the radiator is high enough expanding the spring engaging the clutch. Once cooler air comes through, the fan disengages.
Also, thermal clutches are generally rpm controlled as well. Usually above 3000 rpm, thermals disengage.

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post #9 of 10 (permalink) Old Feb 21st, 12, 04:17 PM
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Re: Mechanical Fan or Clutch for bbc serpentine

The flex fans are garbage as has been mentioned! If you have ever been around one when they let loose you would never consider putting one on! They do not take the revs very well and develope stress cracks!

They actually can cut down on MPG and they do take away HP to run. Many tests out there showing a clutch fan actually makes HP over the flex fan!

Flex fans flatten out at higher rpm's. Eventully they flatten out and stay.......No longer move air as designed

They move the most air when you don't need it: Low RPM
They move the LEAST air when you DO need it: Higher RPM

lots of information on the internet to sway one from even considering one.

Clutch fan all the way!

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post #10 of 10 (permalink) Old Feb 21st, 12, 04:20 PM
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Re: Mechanical Fan or Clutch for bbc serpentine

Quote:
What changes would I see going to a thermal clutch?
The most obvious is the visual, and when the hood is lifted and those old school expeianced guys think " Oh dear here is another one who doesnt know better.."
Another is fan noise, vibration, cavitation of the fan..... quieter...and noise requires energy to create... A free spinning fan requires none...when moving its driven by the moving air.

My Spelling is not incorrect...it is creative

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