dumb and dumber
 

a friend of mine wired is fan on all the time, he has a 1987 gxl n/a and is running a perma-cool fan with 2950 cfm it a metal bladed one, will the fan rob power from the engine if the fan is running all the time or not really??

crossbar

i thought it would but i am not to sure

He has an electric fan right? If so how will it rob the engine of any power when it is ran by the battery?

'couse the fan uses power,wich will put more load on the motor via the alternator having to try and keep up and replenish the battery all the time.if the fan has no themastat,it would be real easy to wire in a switch so you can turn it off from inside.your best off with a built in thermostat,thou,dont wanna forget and overheat your engine!![dont trust them stock gauges,either!]
d

It wouldn't rob physical power from your engine, But could possibly do what was described above.. Depends on condition of your alternator, and if you have a BIG BOOMING stereo playing too with headlights on, Defroster, Windshield wipers... If your alternator is good, I'd imagine you be fine ... just watch your volt meter...

Does it take his car a long time to warmup in winter? :)

Ya I'll agree that it could possibly make the alternator work harder, would not rob him of any HP though. What he could do is hook a 3rd gen alternator up.

well funny thign is is the thermostat he got with it from permacool did not work and the fan never turned on with it and he severly overheated the car, which i think perma-cool should be liable for....voice your opinons



crossbar

nothing you can do will make your alternator work harder.
except for getting a bigger pulley put on it to overspin the sucker.

there is no work being done by the alternator, all it does is spin a magnet inside a set of wire coils. your voltage regulator caps off the voltage produced by this device at 14 volts (your alternator will produce over 18 if you let it).

if your electrical system is seeing under 12 volts from the alternator,
it will draw power from the battery up to 12 volts if your alternator isnt working at all. once the engine revs up and the alternator is producing over 12 volts again, it will give the extra to your battery to recharge it.

depending on your idle speed and what accessories you have running,
you may not be seeing 12 volts at idle. that is about the only time you wont see it though, as after as early as 2000-2500 rpm's you will most likely be hitting the 14v cap. unless you dont know how to drive your rotary powered car, you arent going to be revved that low in a race, even at the line.

so your friend isnt having any power robbed.

now here's the exception:

even if he was trying to race around under 2500 rpm's, the only result would be a dying battery. the repurcussions of underpowering your electrical system can be a weak spark. so in extreme conditions of low-rpm's, yes... you could see diminished performance. but thats about it.

i dont agree with that...the more current the alternator has to produce,the higher the resistance.ever jumpstarted a car?you know,when you go to hook up the dead battery,the engine rpm's off the car with the good battery will decrease,as the motor takes a bigger load.same with a 4000 watt generator,when you run a big piece of equipment,you can hear it "bog" down.also,you will wear out the alternator MUCH faster.just my .02
-d

Extreme example. Go to an audio SPL competition and listen to the motor when mega-watt amps start pulling current.

i heard that there is an adjustable alternator for offroad jeeps that can be put in our cars. anyone else know anything about this

Justin

Dunno about jeep ones... I've heard about several people swapping GM alts in.. do a search on that.. And the 3rd gen alt works..

As for robbing HP, it sure does. The whole "good thing" about an electric fan is that it turns OFF when you don't need it--ie, when driving at ~>40 mph.

The fan turns. The power to do that has to come from somewhere. It doesn't come from the battery, as that would drain it. It comes from the alternator, and when higher demands are placed on the alternator, that does produce a higher resistance to turning, which produces a higher drain on the engine.

Let's say an e-fan needs 10 amps to run. 10 amps * 12 volts = 120 watts. Our alternators aren't exactly "ideal", so the engine has to waste more than 120 watts, just for the fan.

The good news is that 120 watts pales in comparison to the (sometimes) hundreds of kilowatts our engine can put out, so the loss isn't very much.

-Tesla

i have the blackmagic 150 fan 2800cfm, wired so when the key is in, the fan is on. I had it like that for about a year and a half, never had any problems what so ever. kept the car super cool. but then again, ahtt was on a griffin radiator :)

this fan is also on a griffin radiator
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