95 Grand Prix 3100 Cooling Fans. CFM? Amp draw?

[jmgtp]

I have a set of 2 cooling fans from a 95 Grand Prix with 3100. I want to use them in my 3.7L Dakota 4x4. I’ve already converted it from clutch fan to electric and I used the fan I had on hand at the time (and free) from a Nissan Sentra. It has worked fine and keeps the engine at just the same temp as the clutch fan did. I’ve had it on for months and I gained on average about 1-1.5 mpg. Which isn’t bad considering this truck only gets 15mpg.

Yesterday was brutally hot on the east coast and finally the Sentra fan showed its weakness. Sitting in traffic with the a/c on it couldn’t keep up and engine temps slowly ticked up. I let it get a few ticks above the ½ mark before I determined I’d rather be too hot than my engine and I shut the a/c off. With the a/c off it brought temps down in about 2 minutes to its norm.

I want to install these 2 fans from the w-body but I’m curious as to their individual cfm ratings. Regardless, I’m sure they’ll more than double the cfm of the single Sentra fan.

Second question – does anyone know the amperage draw of each of these fans? The circuit I made is good for 40 amps. I may add a 2^nd relay/circuit as a failsafe in the event of a relay/fuse failure so I won’t lose both fans.

[pocket-rocket]

You know what I would do? Use a fan from a late model (94-96ish) Tbird. It's a single 2 speed fan and it's thinner than the DOHC fans, unless those are what you had on hand. I've often thought about nabbing one for my car but I think they are a little taller than the radiator in my car.

Either way I don't see either drawing 40 amps.

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[robertisaar]

after they're fully spooled, i doubt that the pair would draw 40 amps total. probably closer to 20. when they're getting up to speed though, i imagine more.

i would add a redundant relay, just in case.

[pocket-rocket]

I bet if you did the two speed fan, if you staggered turn on times/temps, that second fan kicking in wouldn't draw a whole lot since the blades are already turning.

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[robertisaar]

that's probably true....

the later GM dual fan stuff went from having two fans with only one speed to using a 3 relay setup to have both fans come on at low speed and both come on at high speed. same situation, less of a surge.

[jmgtp]

that's probably true....

the later GM dual fan stuff went from having two fans with only one speed to using a 3 relay setup to have both fans come on at low speed and both come on at high speed. same situation, less of a surge.

Indeed, thats how my Vette works. But I believe it actually can control each fan independently. I know when I reprogrammed the PCM the software allowed me to pick individual on/off temps for each fan - it only has 2 fan relays though. They are much larger than regular fan relays so they may incorporate more than one switch within each. I was surprised to see that the factory programming in the Vette PCM will run the fans even at road speeds up to something around 80mph before it will kick them off! I didn't change that, but I did adust on/off temps to accomodate the lower temp thermostat.

Anyway, back to the truck:
I know a lot of people love to use the Taurus 3.8 fan which is 2 speed and can flow something like 4000 cfm. I don't think the 2 W body fans will flow that much combined but then again I don't need that much. I'm guessing that combined they will flow somewhere in the ballpark of 2500-3000 cfm. I looked into the Taurus fan and it isn't cheap, ebay sellers have caught on that its a popular fan to use. The 1995 Grand Prix fans I already own.

I know at running speed the current draw shouldnt be 40 amps, but the startup draw could be quite high, especially since I only have 1 controller so both would kick on at the same time. I'll probably try it on the existing circuit, if it works once it should work every time (I hope!).

[TGP37]

Next time your engine starts to overheat in traffic, turn on the heater at full blast. It will augment the cooling system....it really does work. Only problem is the occupants will need to stick their heads out the window.

[jmgtp]

Next time your engine starts to overheat in traffic, turn on the heater at full blast. It will augment the cooling system....it really does work. Only problem is the occupants will need to stick their heads out the window.

Wouldn't want to put myself through it! Turning the a/c off was just enough to bring the temps right down. I neverl let the truck get close to overheating. It usually sits a tick or two below half, and in this instance I let it get about a tick or two above half before saying enough was enough.

Few more days and I should be able to install the GP fans. Epoxy coated the garage floor last week and can't drive on it just yet and don't feel much like working on it outside in the heat. Now that temps are more normal (for here) the truck has no problem cooling, but last week we had two days in teh 95-98 degree range that were problematic.