John..

After searching and trying to fit the S4 fan pack in my car, I have finally arrived at a solution.

I will be removing the viscous coupling mechanically driven fan and the aux. backup fan and replacing both of them with a new electric fan on the engine side of the radiator.

The fan is made by Spal and is the most powerful fan on the market. It draws a whopping 20 amps and will flow over 2300 cfm at 13.8 volts. It is a 16" fan. Their only more powerful fan set is a twin pack 11" fan, like on the S4 cars.

I can now say the Bastard will have a part from the new Ferrari Enzo.

Brittany Chen Li

John, Hi was that fan expensive? The fan switch is on my wish list. Britt

John..

$200.00 with the relay and mounting hardware. I will be using the aux. fan circuit to power the relay to switch the high current power to the fan. It should be a sweet deal.

The cheapest S4 fan pack I found was $250, and unfortunately it would not fit in my car with the turbocharger air feed pipes.

The Spal is supposed to be the best available for aftermarket applications. Their number is 1.800.345.0327. I went with a puller fan to free up the real estate occupied by the aux. electric fan.

WallyP

If you can afford the room, fans work better if they are shrouded to operate partially as centrifugal blowers - that is, the most effective way to mount the fan is with half to two-thirds of the blade tips behind (out of) the stock shroud.

You should also make an effort to keep air from circulating back thru the radiator under the car or around the radiator.

BC

INteresting idea Wally. So you mean that the fan is spinning with half the blade in the shroud, and half the blad "width" outside the shroud?

_____ - Looking DOWN from top of shroud

________

________ - Fan blades

________

_____ - Other adge of shroud

User 4221

John,

I'm trying to understand how this works together. With the deleted viscous fan, and electric only.... Does the electric run all the time or only when directed from the factory fan circuit?

Meaning, you have no fan running until the temp switch/AC turns on the fan?

I'd like to switch to the electric setup but with a dual approach:

1) Normal operating conditions, one fan runs when car warms up (controlled by a thermistor ckt.)
2) The AC/Temp switch will run the other fan.

The upshot is that you have two levels of cooling... Light load and heavy load.

A thought.....

Scott

John..

Yes, that is best but I could not fit a twin fan pack in the car (from the S4), there simply was not enough room.

I have ordered a lower temp thermal switch for the radiator.

So in short, the viscous coupling fan will be replaced with the Spal 16" fan.

The aux. fan will be removed (opening up space for my CAC)

The Spal will be activated with the circuit for the Aux. fan from the coolant temp or the condensor temp switch.

This has been done in the past and works really well. If I am lucky, the fan will only run in traffic or while parked.

I investigated trying to drop the speed at idle, but it is too complex and kills the motor life (so I am told).

User 4221

Thanks for the quick reply.... I have some ideas for the variable speed fan but it would require some additional circuitry and consume space.... Something I don't think you have too much of.

Scott

Normy

Wally- my company could use you in the maintenance department to figure out why the number three engine on one of the planes keeps compressor stalling! Good information. I've noticed that the fan seems to "hang outside" the shroud on most cars with longitudinaly-mounted engines.

John- I bet you've read about my radiator fiasco earlier this spring. The long and short of my point is that I tried to re-engineer my car by using an aftermarket radiator. I'm not a mechanical engineer. I know that particular qualification does not automatically ensure that modifications made by the individual are going to be valid...

Why do you want to remove the engine driven fan? I thought long and hard about doing this too. I HATE the "bwAAAAA" sound that the belt driven fan makes during acceleration...primarily because I think it detracts from the great sound of our engines. In the end, I decided that I most likely would not enhance my car by doing this, and could wind up with multiple expen$ive problems.

You're bearing down on that magical 500 hp level like a freight train. You don't think that the 3-4 hp that the fan eats is going to make any difference do you?

My recommendation: Leave the fans alone, unless you are having cooling problems.

N!

ViribusUnits

John, on my car, the aux. a/c fan is fused for 25 amps. It would seem that you would not have to use new wireing for a 20 amp fan. Anyways, just a thought.

Flint

Normy, were not the Euro's orginially devoid of the belt-driven fans, and had to have one added for the benefit of the US smog pump requirement? There was discussion of this before, regarding removing the whole smog pump unit on Euros.

Normy

Flint- the Euro's fans were the same as the US models, with the exception that the belt driven fans themselves had more blades than their American counterparts.

My car has an air pump, though I'm not sure if it was built this way. It is belted, but doesn't have any air hoses, since the cat had its air tubes removed. I'm probably going to remove the pump at the next belt change.

N!

Ketchmi

I have a 18" 2500cfm (Perma-cool #PRM-19117 Summit) fan installed in the factory shroud in my 86.5 which runs off of another relay tied into the aux. fan switch (75C) so that both fans come on at 75c. My car usually never budges off of the lower white line (75c thermostat also) but today in traffic and 100 degree heat it went near the top white line. And that's with no A/C!

I'm thinking that 2500cfm isn't enough in high heat situations. As soon as I hit the highway, it cooled back down, but that's not good enough. I also use about 25% anti-freeze to water and water-wetter as it gets really warm here during the summer.

I had replaced the front aux. fan with an 1850cfm unit earlier and both fans running couldn't maintain temp in about an hour's worth of in town stop and go driving. Even at 90 degrees, it's never moved off of the bottom white line, today was a new experience. I plan on going with a custom shroud and dual 14" fans (5900cfm), or a 14" and a 12" (4600cfm). We'll have to see how things shake out.

I had no cooling problems during the Bonneville 100 running 125 mph for 101.6 miles, never got above the bottom white line. The fans usually only come on when I come off of the highway and sometimes when sitting in traffic.

I would rather err on the side of excess than be caught shy. Marc Thomas (DEVEK) was developing a shroud for dual electric fans for OB's last year but I guess it's not finished. Time for a DIY'er to see what he can do. The fans are cheap, the shroud will be the hard part. We're looking at 2 weeks of high 90's right now, better get off of the computer and get to work.

Dave

John..

We will see how it works. The reason I am replacing the old mechanical fan is to get rid of the backup fan on the front side of the radiator...that is what is holding me back from installing a larger charge air cooler.

I would say the Aux fan coupled with the mechanical fan at idle is still not approacing the 2400 or so cfm of the new electric fan.

Others have done this and it works well.

My car is far from stock, so why stop now?

The mechanical fans are supposed to eat 10+ hp, but that was not my reason for removing it. The damn 928 should have been engineered with more frontal cooling area, then I would not have this issue.

PorKen

Here's one way to increase the frontal cooling area, especially if you are blocking the regular entry with big-**** driving lights...

(2) 3-1/4" holes (made with holesaw) per side.
(The four small holes visible are the factory mounts for the fog-light.)

Without the flash the holes are not visible thru the black-painted 1/4" chicken wire.

I bought a spare bumper support off E-bay before doing this!