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Electric Cooling Faan Requirements

SSuperDave

Veteran Member
Senior Member
I am going to add a 4,000 cfm dual 12" fan setup to my otherwise stock '68 Caprice. The fans draw a total of 50 amps. I know I will need a relay for each one, and a temp sensor for the water neck to trigger them, but how much alternator will I need? Right now I am running a 12SI 105 amp internally regulated unit. Stock on an a/c car was 61 amps, when the original failed, I upgraded just because it didn't cost any more. I do have my headlights run thru relays to ease the load on the stock wiring.
Somethiong tells me I'll be at the lower end of the limit with the 105A, but the running hot at idle issue is in the sun on a hot day, evenings its runs cool.
I don't care to dicsuss the running hot, suffice it to say that the time and money I've spent to try to get the car to cool like it did when it was new is waaaay in excess of what it should have required.
Thanks
 
I am going to add a 4,000 cfm dual 12" fan setup to my otherwise stock '68 Caprice. The fans draw a total of 50 amps. I know I will need a relay for each one, and a temp sensor for the water neck to trigger them, but how much alternator will I need? Right now I am running a 12SI 105 amp internally regulated unit. Stock on an a/c car was 61 amps, when the original failed, I upgraded just because it didn't cost any more. I do have my headlights run thru relays to ease the load on the stock wiring.
Somethiong tells me I'll be at the lower end of the limit with the 105A, but the running hot at idle issue is in the sun on a hot day, evenings its runs cool.
I don't care to dicsuss the running hot, suffice it to say that the time and money I've spent to try to get the car to cool like it did when it was new is waaaay in excess of what it should have required.
Thanks
What other accessories does the car have? Do you have an audio system, A/C? Power accessories?

If you upgrade an alternator too much wiring will also have to be upgraded.
 
Its a factory air car, and I have an aftermarket stereo with no additional amps. No other changes from stock. I was hoping to avoid rewiring if possible, I know thew bigger uniotes require it.
 
Just thinking If you turn on all accessories, blower on high, lights wipers radio, what is the AMP draw on the alternator?
 
I think you'll be fine with the 105 amp. Biggest draw by far will be the rad fans, headlights/running lights next, then blower fan.
 
I have no way of knowing that, and have had no luck googling that info. My only guidline was that 61A was good for stock, add a 50A load is 110A and I am charging 105A now. I'm feeling I'm on the borderline, but would like to know more.
 
I’m using a 135 amp Load Boss on my car, Vintage ac, RetroSound stereo, Windstar dual Efans on separate controllers, 2012 Camaro power Drv seat and no issues, I’d leave the 105 amp in it and see if your lights dim with the Efans and ac on, if the lights are dim get the 140 that Kevin posted or the 220 from DB for a little more
 
Why go away from the simplicity of a good shroud, fan and clutch ? :unsure:
I don't anticipate having any cooling problems with a hi-po BBC with ac.
 
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Beth, tried it all, have airflow issue at idle/low speed. I don't have time to go over everything I've done to this stock vehicle...
 
I’m not sure how big of Load Boss you can get amp wise but IIRC they’re made in Texas
 
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