electric fan

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  #1  
Old 07-22-03, 02:37 PM
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Question electric fan

I am going to replace my existing clutch fan with a double electric side by side fans. I intend to build a thermostat for each fan and put the sensor on the radiator. I was also toying with the idea of building a speed control system, to adjust the speed of the fans based on the tempature. I also intend to have a multi position switch that would enable to have both fans on all the time, controlled with a thermostat for on and off, or have the thermo sensor controll the speed. Can any body reccomend if varying the speed is a good idea or should i just make it a simple on off.
 
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  #2  
Old 07-22-03, 05:51 PM
Joe_F
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What type of vehicle and why?

You won't gain all that much dumping the clutch fan. Some vehicles have both, that's what I'd do if you're hellbent on the idea
 
  #3  
Old 07-22-03, 06:37 PM
knuckles
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There's no need to build your own thermostat, or to vary the speeds.

Hayden and others make prefab thermostat kits. You could also create your own kit using 2 different GM thermostatic fan switches. Wire each switch to its own relay & fan

For example, buy one switch that kicks the primary fan on at 195F. Buy a second switch that kicks the secondary fan on at 210F.

Wire each fan & thermostatic switch to its own relay. When working correctly, the primary fan will kick on at 195F. If engine temps continue to rise (towing up a long grade, extended WOT acceleration, carrying extremely heavy loads, operating the a/c in heavy traffic w/ extended idle periods) the secondary fan will kick in.

Many OEM setups are very similar. The primary difference being that the PCM uses the ECT to read coolant temp and turn on the fan(s) accordingly.

You can buy cooling fan thermoswitches from nearly any parts store. Ask to see their catalog & look up the specs on each unit to get the low temp & high temp switches.

Alternatively, you can buy a low temp fan thermoswitch from Hypertech and a 'stock' high temp switch from any parts store. Order a switch from a 1987 Camaro w/ 305 TPI or 350 TPI engine.

Hypertech's switch is no bargain. You can do better if you research the specs. in the back of the parts book at your local autoparts store.

Again, though...why do you want to do this? You'll see a very minimal HP gain. Nothing is free. HP is lost to turning the fan & clutch, but nearly the same amount of HP will be lost to the alternator when the fan(s) are running.
 
  #4  
Old 07-23-03, 05:29 PM
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The type of vehicle I am installing it on is a 1986 F150, with a 302 cu in v8. I have read and studied many reports that electric fan can give better horsepower and increased mileage. I was just pondering the logic of using an adjustable speed control. I appreciate what knuckles said. About setting the thermostats at two different tempatures. for increased load and temperature ratings. Thankyou guys.
 
  #5  
Old 07-23-03, 05:45 PM
Joe_F
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As Knuckles said, zero benefit. Keep the stock clutch fan in good working order and you'll be fine.
 
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