6.0-928S

I'm at the point where my stroker is almost ready for initial startup. It's time to buy a cooling fan setup. I removed the original clutch fan. I plan on getting an electric fan kit from one of the 'List suppliers. I intend to use one of the 951 type multiple fan switches to run both the auxilliary & primary fans. While price is not my primary concern it factors in, I will not overpay. Who has purchased what kit & what are your reviews? How do you like what you've installed? Are you happy with the balance of performance versus cost? I'm interested in hearing from those who have done it.

TIA, Hammer

danglerb

I don't think any of the aftermarket kits are OEM quality. I use a fan off a Lincoln Mark VIII with a DC Controls PWM controller, but its not plug and play. The Mark VIII flows more air than anything else I know of for a car, 18" optimum 50% coverage blades in a ducted shroud with a Siemens 35 amp continuous motor. The slightly smaller Taurus fan is pretty good and so is the dual fan out of the Ram Charger.

Lincoln Mark VIII Motorcraft RF64 sells new for around $300, used on ebay about $80.

Unfortunately DC Controls doesn't like pesky new customers, so they only sell to the Mustang and rock climbing jeep types groups, but they make the best controller and the only PWM with enough current for the Mark VIII fan. 75 amp Bosch relay and a temp switch work fine for many, and one ebay guy sells a relay package for two speed operation.

That said ....

With a big enough radiator almost any fan is ok, and if the radiator isn't big enough almost no fan will make it work.

IcemanG17

I think 928 Specialists and Carl are the only ones who make kits?

One thing to consider since you are coming from a non electric fan setup is how you want to control the fans.....the S4+ had a variable speed setup with LOTS of different inputs (air & water temp, AC & AC pressure etc).....

In my race car I elminated the stock variable (uses a temp sender bottom of radiator) system and went with a straight 180F switch right in the stock senders place...then wired a simple fuse-relay right off the hot post...so at 180F the fans come on at full voltage and turn off just under it.....

PorKen

Great tip! I was wondering how to wire my dual 11" SPAL in sequence.




I did a little searching, and found that the 3 terminal fan switches are used on many VW, Audi, SAAB, etc. Note the middle two appear to have different on/off ranges. The middle terminal is the common.

191959481C | 95-81/102-91c
321959481 | 85-80/93-88c
251959481K | 85-74/93-82c
25195948175 | 75-70/82-77c

6.0-928S

Exactly Ken. There are more temp choices/switches than you have listed. There's a guy on ebay that sells about 10 different ranges. I don't have the link, I ran across it a few months ago doing a search.

Hammer

UncleMaz

I notice vendors on here selling in-line adapters. I would use two senders, kicking on at diff temps., with a relay for each fan. off of one fused line from the battery with a one way circuit breaker for blow back.

PorKen

What's nice about these 3-term senders is that they have two switches inside, which come on at different temps.

I am going to wire one fan to the stock electric fan circuit (plugs right in), using one of the terminals, and another relay to drive the other fan with the second.

UncleMaz

Nice. Thanks for clearing that up. I have only used the two post type.

danglerb

Great find on that double switch. Does it fit our radiators spot?

How about we come up with some relay circuits, with maybe a few options and features.

The radiator only has the one spot for a thermal switch in the front of the return (not hottest) tank.

Dual fans, or a dual speed fan.

Manage the Aux fan, which I think generally should be off if the main fans are working, but turn on if the main fans don't.

What should happen with the AC circuit? I'm thinking if low temp main fan switch isn't tripped, then turn on main fan at low speed. If the main fan low temp switch is on, then main fan to high speed. Maybe if main fan high speed switch is on then main fan to high speed AND Aux fan on.

Comments? Suggestions on a relay circuit?

Any sources for the dual switch connector?

Ideas for the set points of the two thermal switches?
Note, during normal operation I think the return side tank is about 150 F.

David L. Lutz

Good question and are the threads/size the same on an MY87 Rad.

Does anyone know the thread size on the sendor?

chrly924s

I just got one for my 951 from Autohaus for $12.53. The threads seem to be 22mm. This is a 85/93 degree switch.

chrly924s

Sorry-PN is 951 606 48100

6.0-928S

The switches are all the same thread as our rads have. As I said in the original post, I will run the auxiliary (a/c) fan post from one terminal & the main cooling fan from the other.

Hammer

soontobered84

I used the Audi two fan/two speed setup for the '83 and it basically just dropped right in and bolted where the upper shroud bolts. Jim M. has the part number for the assembly in his PDA. There are two fans: one driven directly by a motor and the other driven by the same motor and a small belt.

GlennD

Just wondering if the switches in the temperature sender are capable of dealing with the current required for the fans.
I would wire the switch contacts to a set of relays (one relay per switch) and use the relay contacts to drive the electric fans. The relays can be purchased with the correct current ratings (e.g. 20 amps per contact set). The relays could be simple (e.g. SPST) 12 volt relays.
If you decide to use relays, I would also suggest putting a snubber diode across the coil (IN4001 or similar) to prevent the back EMF from getting into the electrics of the car.
Back EMF (electromotive force) = induced voltage when power is removed from an inductor (the relay coil). This induced voltage is equal to
V = L dI/dt or the inductance of the coil times the change in current over the change in time (time would be short since the relay coil is being driven from one to off in the time it takes the temperature switch to open).
Cheers