electric fans

I did custom electrics in my Capri when I stuffed a 351 back under the hood. I built my own controller, a 2 step to run both fans. Because of the width, and the fans I had, I had one push and one suck. Worked ok.

Points to note:

Get the fan as humanly close to the rad as possible to minimize cavitation, unless you make a shroud to get the air past the fan away from the leading edge,

Provide some form of protection to the rad, a couple pieces of 3/16" rod is good, to keep the fan from chewing on the rad, if the fan mount moves, or worse yet, you loose a bearing in the fan. Better to have it grind on the rods, which you will hear, than the radiator which you probably won't.

If you make your own controller, it's probably easier to calibrate it with the probe in a pan of boiling water with a candy thermometer, than it is stuffed under the hood or the dashboard. I also built a little bit of hysteresis into the controller, meaning as soon as it hits the cool point it runs another 30 seconds or so, that way it doesn't sit there and click on and off every 2 seconds.

My temp probe was a thermistor from radio shack jb welded into a drilled pipe plug that went into the water jacket just above the thermostat. I think it's better to look at the water temperature, than the air coming past the rad.

Probably a good idea to have indicator lights showing fan on/off so you know it's working, I also added manual over ride switches. (I like buttons).

Also... this is an important one... if you do fab your own controller, spend the money for the slightly more expensive chips... get the MIL spec parts. the temperature range goes a lot further. Hot end isn't so bad, but when it got below 20F my controller wouldn't work until the cabin heated up some. Too cold, and the op amp chip wouldn't work. Mil Spec is -40 to 110C if I remember right.

Food for thought!
 
MIne are set to come on full when the AC clutch engages...if not they come on 60% @ 165* then ramp up from there.
The Flex-A-Lite controller is really nice and simple to use.
 
unbroken those temps dont sound bad, my 07 is stock and you can watch the stock gauge creep upto 200-205* on a decent hill all by itself in warm weather.
 
They aren't too bad. My truck usually stays right around the 185-195* mark, even when it is pretty warm out. And you can tow with them you just have to watch. Shawn towed my truck all the way to the Diesel Power Challenge in Salt Lake City (a 24hr drive one way) with his truck and he has electric fans and we never overheated it once and was pretty hot out on the trip down and back.

Tyler
 
I should have noted that my stock 06 Cummins runs 200* all the time...empty or towing...so these fans actually keep the modded Cummins in my black truck quite a bit cooler than my stock work truck.
 
strokercuban85 said:
how would the electric fans hold up the miami heat ?
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I've been in Florida for a couple of weeks...including a trip down to Ft Lauderdale...everything has been fine.
I've seen mid-high 90's almost every day since I've had them in with zero issues.
 
i think im going to go with the dual flex-a-lite fans for the 7.3 and modify it for the 6.0 , where do you guys think i can find it for a good price.
 
Is it a surface area issue or a volume issue? What about getting 4 smaller diameter fans and building a custom aluminum shroud. I was watching muscle car on Spike a while back and the made their own electric fan setup and shroud with a sheetmetal bender and a plasma cutter. If you could determin the volume of air the stock mech. fan draws and source 3 or 4 smaller fans to equal that, keep en close to the rad and seal up any air gaps i think we'd be in buisness. Kleetus mention something about the alternator. Dou you think that it will not hold up to the extra amp draw?
 
I think you'd be asking a lot of a unit with internal diodes. What Ford calls a heavy duty alternator and what the rest of the world called a heavy duty alternator are two different animals. I have dual on mine, but even so, they're 130A each, and neither is larger than the 70A I had on my 86 merq.

The windings can take the heat, it's the electronics that take the beating. our trucks have a pretty decent electrical load now, computer, stock fuel pump, injectors, accessories... If you're modded, with a bigger and badder fuel system, that's all the more load you'll have. Adding fans to it isn't going to make it any better.

For a drag truck, yeah, you might see *some* difference, less than 5% my guess. But for a daily driver, I think you're asking for trouble. There's a reason OEMs don't use electric fans in trucks. They've been doing this a lot longer than we've been re-engineering them.
 
Kleetus said:
I think you'd be asking a lot of a unit with internal diodes. What Ford calls a heavy duty alternator and what the rest of the world called a heavy duty alternator are two different animals. I have dual on mine, but even so, they're 130A each, and neither is larger than the 70A I had on my 86 merq.

The windings can take the heat, it's the electronics that take the beating. our trucks have a pretty decent electrical load now, computer, stock fuel pump, injectors, accessories... If you're modded, with a bigger and badder fuel system, that's all the more load you'll have. Adding fans to it isn't going to make it any better.

For a drag truck, yeah, you might see *some* difference, less than 5% my guess. But for a daily driver, I think you're asking for trouble. There's a reason OEMs don't use electric fans in trucks. They've been doing this a lot longer than we've been re-engineering them.
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This is true. Most heavy duty alternators go to external voltage regulation. Some of these dual fan or quad fan setups are going to pull 80 to 100amps at full tilt. The 27 inch fan coupled to the motor is pretty hard to beat using a few 13, 14, 15 or 16 inch fans. 100amps on a single alt truck will be a continuous draw on the batteries. You will kill that alternator. Even a 200 amp alternator only puts out ~40 amps at idle. They all have a curve for rpm vs amps. 200 peak amps is only available if the motor was turning ~2000rpm or higher. Hell the A/C blower motor pulls 30amps on high. Then thing about the 4 12v circuits into the FICM that are putting 20 amps into the injectors.
 
Burner said:
I thought the fans had a rating?
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When hot.. ever have that really loud noise when the stock clutch engages??

When it does engage the oem fan is pulling 7500 cfm...!!!! Nothing electric compares. If you dont get it hot then electric could work. Also when engaged its eating if I recall correctly 27 hp. could be a bit more. But when its free spinning and not making that really loud noise its only eating .25 hp. The 6.0l clutch fan is the best oem to date.
 
I wonder, would they would be more effective with reduced radiator fins? You are 'pulling' air and the fins soak and release the heat but also become a drag. If you reduce the drag enough to speed the air across, would they be more effective?
 
In a word, no.

You need the fins for surface area. If you removed the fins, to get the equivalent surface area for heat exchange you'd have a radiator 10 times larger... and heavier.

The pressure drop across the rad really isn't that bad. Even if it was reduced, now the air is going to crash into the motor 6 inches behind the rad. You're not really gaining anything tangible.
 
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