924Board.org

[Ian89C4]

Well, I was running the race car for a little a few days ago and noticed a rather bad crunching bearing sound...needless to say I was less than amused. I stuck my head down as far as could into the front of the engine cavity listening as well as I could, revved the engine to try and catch where the bearing noise was coming from and just hoping that it was not the alternator as I just replaced it or the water pump as it is brand (ish) new and I have not ever had the car that hot.

As she was just sitting there I had the fans on low (I have them switch operated with a high and low setting) to keep her a little cool as it was like 40 degrees outside and I was only running her for 15 minutes. As I revved the engine the grinding sound stayed at a constant speed....thus leading me to the fans. I turned them on high and the sound went away, turned them back to low and the sound returned. Looks like my 30+ year old fans were heading south on me. So......

I went to local auto store and got two 10 inch Hayden fans (about $100 for both). They pull about 550 CFM each through the radiator which I figured is close to what the originals pulled (could not find anything verifying that). And they run off of a 25 amp circuit which is what ours operate off of.


I then used a few feet of aluminum stock to create a frame (I can provide dimensions if you would like)....




After measuring a million times and marking all the holes you are ready to drill the holes fasten everything together. I used 3/16th rivets on the frame and middle fans stays ( I used angle aluminum to provide strength, but wanted to allow max airflow through the center). I used grade 5 bolts to fasten the fans to the frame and over-sized the holes a little so that I had a bit of adjust-ability.



On these fans the blades and wiring have to be reversed for a puller settup.

Then, using the stock mounting brackets on the radiator, just attached her in... (photo is sideways and although there looks like there is no space between the frame and the radiator there is about 1/4 inch)


Wiring is easy. On the stock plug there are three wires going in. One is the hot wire (attached by itself to one side of the harness plug) the other two attach to the other side of the harness plus, looks like a ground and another large wire. You will have to excuse me, I am terrible about looking up where each wire goes onto the harness or what it exactly does, I just try to mirror the original harness build.

I completely cut away the original female plugs and used bullet connectors as corrosion inside my wires was causing a lot of resistance and causing my battery light to start lighting up when I turn the fans on (well, assisting in it, I am pretty sure the fans getting old and pulling more amperage to work is that cause, I hope)

If you stock harness is good, then you could just slap some male spade connectors on the new fan wires and be good to go.


To test the fans just jump the two wires that are going in the thermo switch on the radiator and upon turning the ignition to on, you should get the fans running.


The fans work on both my high and low settings and move a good amount of air. I have other components off of the engine or I would let her sit there and report how cool she stays.

You can of course paint the frame and make her look all schnazy, but I am impatient and I kinda like the raw look with marks on it.

Hope this helps, cheers.

Ian
_________________
Ian Edgerly
North Carolina

Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala")

[Rasta Monsta]

Nicely done. Did this operation lose you weight? I've always thought the factory assembly was awfully heavy. Also, did you consider using just one fan?
_________________
Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[Grenadiers]

Hey Ian, nice job as usual!
_________________
'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

[Ian89C4]

Thanks guys!

Rasta -

I thought about using just one 12 inch fan, but I am worried about those hot summer days here in the South where on track can hit 120+ at Roebling Road in August. If she over-cools her self I will probably switch to one fan, or just create a circuit for each fan.

Weight wise we are really not loosing a whole lot of weight, I would say about 1 or 2 lbs. I am really close to my minimum weight in SCCA ITB as it is, one or two lbs lost is about all I can do (2495 min weight and right now she is 2550 with me in it and half a tank of fuel)


Note: Finished doing my other stuff on the engine and let her get nice and warm. The fans on low maintain a perfect temp with the ambient air temp being ~40 F, with the fans on high they cool her down significantly.

Cheers,
Ian
_________________
Ian Edgerly
North Carolina

Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala")

[CorsePerVita]

This is a sweet writeup, thanks for sharing!
_________________
- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS