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Robert
Dodge Dakota
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2/06/2004
01:53:51
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 Subject: electric fans
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Message:
anyone ever put an electric fan in a 4.7 Dak? i am wanting to free up a little HP and i know this will help. thanks for the info
Rob
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EBL
Dodge Dakota
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2/06/2004
11:54:52
| RE: electric fans
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Yes, Dodge placed a mechanical and an electric in the 4.7. (at least some of them.)
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Dikgozinia
Dodge Dakota
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2/06/2004
12:13:49
| RE: electric fans
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It's not worth it,, the horsepower gains will be very minimal.. Also, Elec is bad: A fuse could go, wires ground out, or fan doesn't operate then you could be in a lot of trouble.
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Fan
Dodge Dakota
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2/06/2004
20:22:53
| RE: electric fans
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A electric fan really sucks.
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R/TBlues
Dodge Dakota
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2/06/2004
20:50:18
| RE: electric fans
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All the 4.7's have an electric fan and a mechanical fan. Many people have removed the mechanical fan with no problems. When the clutch fan engages it robs anywhere from 5-10hp. I'm going to remove the one on my R/T. The electric fan acts like a back-up to the mechanical fan. For example: When your sitting at a redlight in 100deg weather with the AC on. The mechanical fan doesn't pull enough air at idle so the electric fan kicks on. If the electric fan is good enough at idle to keep the engine cool then it's good enough period. When your driving on the highway you have enough air coming through the grill wihout a fan. I'd remove it. It's free HP. It's the cheapest modification you can make.
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ScatDak
Dodge Dakota
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2/06/2004
21:20:18
| RE: electric fans
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If an elecric fan sucked then why would they have used them for over twenty years on all front wheel drives. free horsepower is the best horsepower.
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Robert
Dodge Dakota
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2/07/2004
03:07:11
| RE: electric fans
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are there any companies that make after market ones for the 2000 4.7?
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R/TBlues
Dodge Dakota
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2/07/2004
11:09:01
| RE: electric fans
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Robert,
Is there a reason you feel the factory electric fan is not sufficient? I've never heard anyone complain about overheating after removing the clutch-fan. I'm sure there is an aftermarket fan that will pull more air through than your stock electric. You will have to fabricate a way to mount it. BUT WHY? The factory electric fan works PERFECT. If you purchase a new electric fan then it's no longer "FREE HP". What's even worse, the aftermarket fan you paid $100-150.00 for might not be as good as your factory fan.
Just unbolt the factory clutch-fan. You will have to go find some shorter bolts to hold the pulley on or stack a bunch of washers under the original bolt heads (not recomended).If it ever tries to overheat put it back on.
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Pressed On
Dodge Dakota
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2/07/2004
20:05:57
|  RE: electric fans
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The 4.7 pulley won`t come off. Just have to remove the big `ol nut. No worries.
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Dave Mitchell
Dodge Dakota
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2/12/2004
18:41:29
|  RE: electric fans
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Electric fan -
An electric motor is only 80-85% efficient. An alternator is only 80-85% efficient (check any eletcrical engineering reference for verification).
Therefore, to MOVE THE SAME AMOUNT OF AIR, at 30% less efficiency, your engine would have to apply 30% more HP and torque for an electric fan, at best.
Don't forget that the engine also supplies the mechanical power to the alternator that feeds the fan. There is no such thing a s a "free-perpetual-motion-machine".
Watch for sludge in the crankcase when installing 180 degree thermostats, also. Under some conditions, that mod may not be ideal. Damp and cool environments, such as Oregon coast with short distance drives are an example.
Probably work great at a drag strip, though, if you do all your driving there.
Dave
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GraphiteDak
GenIII
2/12/2004
19:04:18
| RE: electric fans
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Message:
I've been pulling my trailer with my 2003 since last summer with no clutch fan and it doesn't overheat at all. I think removing the clutch fan may have given me 1 more MPG.
I use a home made electric fan control to cycle my fan on and off at a certain temp I set it at. If you don't do this your fan doesn't come on until over 200 degrees from what I heard.
I keep forgetting to make a schematic of the elctric fan control built with cheap Radio Shack parts. Several people have emailed me for it. I just made mine out of the top of my head. It connects to the stock temp sensor and works great.
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GraphiteDak
GenIII
2/12/2004
20:21:59
| RE: electric fans
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OK. I quickly drew up the fan control circuit.
I made it from memory so some info may be wrong. I think it's correct. The (-) and (+) inputs to the IC (pins 6 and 7) may be reversed.
If you make a circuit board connected just like that it should work. It is very cheap. Just build it on a cheap board and install in a project box.
Connect the input to the temp sensor on the top of the engine.
Mine was a Purple wire with a Orange Stripe.
Fan relay is a general purpose relay found in Autozone, etc.
IC is a 339 Quad Comparator found for like $1.19 at Radio Shack.
I used a general purpose NPN switching transistor.
Resistors were 1k ohm.
I used a 100k ohm variable resistor to set the reference point to the input of the comparator.
Check DC volts at pot and set for approx 1.1 Volts to start then fine tune once the engine has warmed up so the fan cycles on few degrees over your T-Stat temp.
The 100MicroFarad Cap is just to help the the relay from chattering when it is switched on or off.
You may also install a filter Cap on the input of the IC from the temp sensor. Make sure it's on the IC side of the 1k resistor so it doesn't mess with the signal to the PCM from the temp sensor.
I used a project box with a sealed Molex Connector shown here.
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RadioMan
Dodge Dakota
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2/13/2004
06:57:40
| RE: electric fans
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Message:
GraphiteDak, VERY nice job on the control. Now
I think I'm gonna do the very same thing this
summer to my 02 4.7. Remove the clutch fan and
leave the T-stat as is.
Again, great idea!
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GraphiteDak
GenIII
2/15/2004
22:22:29
| RE: electric fans
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Message:
OK guys. I went to the Dunes (near Yuma) this weekend. Pulled my load of Quads on the trailer (and one in the bed) and this time I was back to my 195 t-stat and my electric fan set to cycle just above that. The clutch fan still removed. I didn't notice any loss in power OR response. It pulled like a mo fo as usual. And had the nice initial jump out of the hole as well. It's kind of funny. With the trailer on and even a quad and luggage in the bed enough to load down the back of my 4X4 an inch or so, the truck will rip the tires if i get into it too much from a stop.
So, basically I'll leave that 195 t-stat in there. It always helped me with COLD t-stats in carbed engines (with heated intakes) but seems to do nothing for a stock 4.7.
Now if you were running maybe some BOOST or had higher compression THEN you may need it colder t-stat (plus a colder plug) but I for one have tried both the 180 AND the 160 t-stat for months (no problems) but since it does nothing I'll leave it alone. Maybe it will reduce the chances for that oil milkshake I hear about in the oil filler. Not that it would probably ever happen to me here in Arizona.
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GraphiteDak
GenIII
2/15/2004
22:42:19
| RE: electric fans
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Message:
OOPS!
Looking at my schematic I forgot a few things which I fixed just now. So if you saved that pic before you will see some changes.
I had forgoten a trace going from the pot to the IC pin 7, the pin outs on the transistor (base, emmiter, Collecter), and the 12 VDC regulator. The regulator will keep a absolute 12VDC to the IC control. Without the regulator and how the 12VDC doesn't stay the same on a car, you could get erratic operation. I dunno because I never tried it without the regulator.
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