electric fan install, grand prix fans (done)

[matthufham]

got some fans off a 2000 GTP, they're similar for years on the 3.1 and 3.8, and shared with impalas and possibly others. I found a spec sheet of these fans with measurements, attached picture.

wiring is upper medium skill level. they're dual speed fans, and I used 3 relays as factory does. attached picture of that. i'm running the low speed off an oil pressure switch, usually used to turn on fuel pumps when the engine is running with oil pressure. the high speed i'll be activating with a thermal switch that reads coolant temp. on at a higher temp, off at around thermostat temp. for now I just have it on a toggle switch until I find the proper temperature switch.

Low speed runs 2 fans through each other. (12v in and out fan 1, and into the fan 2, then grounded. more or less a series circuit.

high speed runs 12v and ground to each fan

I have yet to make brackets to mount the fan assembly, but it'll be easy enough with the welder and some brackets I'll fab up. the main part is complete and I thought i'd share.

and a side note. the top is square, the bottom is rounded... which fits. I found though the bottom fits better on the top with the radiator hose on the driver side. so when I mount them permanently , they will be mounted upside down.

I also attached a video that shows them running, and a glance of the relay setup.


if you click the above image, this is the video I spoke of which i'm hoping will work for you, it worked when I clicked it (opened windows media player)
If the video doesn't work for you here's a link to photobucket.
http://s1304.beta.photobucket.com/us...08567.mp4.html

[72 K20]

Looks like a nice setup !! I found this on the auction site,, would definately be an economical way to go to electric cooling fans.

http://www.ebay.com/itm/Pontiac-Gran...c9b2ab&vxp=mtr

I'll be watching for progress and performance updates !! Thank you for posting this !

Have a great day !!
Tom

[Longhorn 70]

Just curious, in pic 2 it looks like barbed wire between the grill and the radiator. Is that to keep cats out?

I think I'll try that to keep the ferals away.

[matthufham]

Yup, cats
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[BlackedOut67shorty]

What amp alt are you using and is it exteranlly regulated¿

[matthufham]

Originally Posted by BlackedOut67shorty

What amp alt are you using and is it exteranlly regulated¿

I forget because it was 2005 when I put it together, but I believe a 70's or 80's Chevy, it's a 1 wire alt, under 100 amps, then did whatever needs to be done to the regulator on the core support for the conversion, lots of how to's on here
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[VetteVet]

This thread grabbed my attention because I have a 97 GP SE and I measured the fans just to see if they'd fit in my 67 SB and they were too wide, I never thought to turn the shroud upside though. I can't use them anyway because I need them for the car but I can get some from other sources. I have since bought a 16 inch single speed fan that I will use.

Your project brings up a couple of questions on my part.
1. I have read that the dual fans are needed for cars with AC., which most all do nowadays. Also the drivers side fan is higher capacity because the radiator gets the hottest fluid through the upper left intake if the upper hose is connected there. I don't know if this is true but I have heard that. If it is true then of course turning the fans upside down would put the higher capacity fan on the opposite side. This may be a moot point with dual speed fans and they may indeed be the same capacity. If the drivers side is stronger then maybe you could just turn the shroud if both fans mount the same.

2. If you used the oil pressure switch to power the low speed windings, won't the fans be running all the time when the engine is running or is that your desire?

3. Lastly how are you going to wire the fans so that both speeds aren't running at the same time When the high speed kicks in? I think the ECM does that on the cars but we don't have ECMs on the trucks. I believe it can be done with switching relays but I want your input.

[72 K20]

why the 2 speed fans ? Does the low speed run all the time and when temp is reached the high speed kicks on ?

Tom

The above post wasn't there when I started typing. Sorry for a partial repeat.

[matthufham]

Originally Posted by VetteVet

1. I have read that the dual fans are needed for cars with AC., which most all do nowadays. Also the drivers side fan is higher capacity because the radiator gets the hottest fluid through the upper left intake if the upper hose is connected there. I don't know if this is true but I have heard that. If it is true then of course turning the fans upside down would put the higher capacity fan on the opposite side. This may be a moot point with dual speed fans and they may indeed be the same capacity. If the drivers side is stronger then maybe you could just turn the shroud if both fans mount the same.

Not an engineer but here's my thought. A small cars radiator is not square but rectangular. Why? Figment. So what fits better 1 or 2 fans? In this size 2 fit well side by side. But you'll see them in opposite corners, and one big one small. And realistically I know every fan setup is different as far as cfm output ratings are concerned.

I don't know what the cfms are with this setup but here's what I do know.
They blow hard even on low, and match my leaf blower on high.
They will do the job, if not better than the flex fan I had on here.
And I know nothing about a fast fan/slow fan on a certain side. to me that makes sense, but I feel these are the same fans and they get equal voltage, blow the same.

Thinking of air conditioning on rooftops at work or home, a lot use just one fan. it's pretty much whatever gets the job done in relationship with the shape of the condenser. I think I answered all that

2. If you used the oil pressure switch to power the low speed windings, won't the fans be running all the time when the engine is running or is that your desire?

Yes, yes

3. Lastly how are you going to wire the fans so that both speeds aren't running at the same time When the high speed kicks in? I think the ECM does that on the cars but we don't have ECMs on the trucks. I believe it can be done with switching relays but I want your input.

I did attach the wiring diagram I used for reference. It's a switching relay in the middle of 3, that wires through the normally closed side for low, and normally open side for high... well not exactly like that because the ground that's cross tied and other tie ins, but that's the gist of it.

If you follow the wires on the diagram and eliminate the 2 of 4 fan circuits (3.1/3.8) then here's what's left. 2 motors, 3 relays (poles 30, 85, 86, 87, 87A), fuses for 12 v input, and an ecu that just sends 2 ground signals. You can choose what you want to send a ground signal to the relays to close the circuit (oil press switch/ thermo switch, toggle switch, even brake switch for heavy traffic) so I think it's fairly simple if you can match the pin out numbers which are common to every automotive relay. And know you have pos and neg on the coil (85/86) then wire in (30) out 87 n.o. Or 87A n.c. Or as in this case running from 87a backwards out 30 for the middle relay. I'm over speaking the relay subject, and a terrible teacher. So any more relay comments will be linked to a couple great online resources on automotive relays.

Hopefully that answers all.
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[72 K20]

I like this setup !! And if it works for you in Texas it should work in Iowa !!

I'm saving this thread !!

I have yet to make brackets to mount the fan assembly, but it'll be easy enough with the welder and some brackets I'll fab up.

So,, how did you end up mounting them to the radiator ?

Thank You !! Tom

[matthufham]

Originally Posted by 72 K20

I like this setup !! And if it works for you in Texas it should work in Iowa !!

I'm saving this thread !!

I have yet to make brackets to mount the fan assembly, but it'll be easy enough with the welder and some brackets I'll fab up.

So,, how did you end up mounting them to the radiator ?

Thank You !! Tom

I work overnight and this is like the first thing I've done on this truck in years. If my lazy butt will get it done this weekend I'd be surprised. Basically some wings will be added because the core support has two flat places beside the radiator.
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[VetteVet]

Thanks Matt I see you are up on all this and have given it much thought. You certainly answered all my questions. I know that my Grand Prix fans blow pretty good on low as well, and I don't recall they've ever kicked in on high. I haven't been in heavy traffic on hot days with it though. I guess I'm trying to say that if the fans on low will keep the engine cool most of the time Then triggering them on the low side with a temperature sender might be better than having them run all the time the engine is running via the oil pressure switch. JMO and please don't take offense, because you have done a great job on this project and helped a lot of guys including me.

[matthufham]

In my street sense opinion.... Fans on high are loud and annoying. That's why I would rather them be on low mostly, and I know many cars turn on high whenever AC is on.
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[airdale94]

That barb wire is BA! If you could get it chrome that would really set it off.