toofer

Decided to replace my belt driven cooling fan with an electrical fan on my 1980 928S because of a smog pump failure and with no emissions here in Florida I thought it might be a good time to ditch the smog pump and upgrade to an electrical fan. Purchased a FFD 16" cooling fan rated to put out 3000cfm at 2200rpm. Installment went nice, tied the electrical into the coolant sensor at left front of radiator and used a nearby ground. Started it up and all seemed to be fine, the fan was pulling the air through the radiator when it kicked in as motor started to warm up. However, it won`t level off, temp guage had never been passed the 3rd line, usually stays right in the middle even in heavy stop and go traffic. Now it just keeps climbing. Can`t drive it like this, if I turn on the AC hoping the aux fan would help cool it down but that just made it climb faster. I`m wondering if the fan isn`t providing enough air so I held the rpm at 2200 just to be sure I was getting max cfms but that didn`t help either. Anyone had any experience with FFD fans?? I`m contacting the vendor but I don`t know how much help they will provide. Any ideas out there. Something I overlooked or missed. Any help will be very welcome. Toofer

Louie928

Have you checked to be sure the fan is turning the right direction. That is check to see if it is pulling air in from the front and not pulling hot air in from the rear? The cooling being worse with the front fan going is a tip off that it could be wrong way air flow. How do I know this? Personal experience.

I don't think the thermo switch down at the lower front of the radiator has contact rating for the current the fan requires. You may want to check the specs on that to be sure. If it doesn't, use a relay to operate the fan with the thermo switch controlling the relay coil.

Louie

toofer

I`m possitive it`s pulling air thru the radiator and pushing it towards the motor. I have read enough posts to get that much right. current draw is another thing. Are you saying to add a relay, if so what relay, and add another temp switch??

Louie928

Hmmm. Well then, it should work. The temp sensor down at the lower front is meant to activate emergency level cooling. The top of the radiator will get hot a lot sooner than at the bottom. I don't know enough to say that would be a recommended location or some other location would be better. I'd use a different location myself. There are electric fan control units (with relay) available. I'd suggest using one of those. Possibly someone else who has installed a fan like yours will give their experience with it and what conditions they observed.

Louie

davek9

Here is a link to one the 928-motorsports sells
ftp://928m:928m@70.226.52.38/installpdf/auxfankit.pdf

also DR has this twin set up:
https://www.928gt.com/productspecs/40372.htm

toofer

Thanks guys, I think I`ll go the kit route, sounds safer than trying to reinvent the wheel.