SQLGuy

Hi folks,

A while back I installed a Murf kit in my '88 S4. Not wanting to pull my louvers and louver motor, I went with two 11" pushers fans in front instead of the recommended 16" pusher fan. The kit comes with 4 8" (? or maybe 9") puller fans, but no pusher fan(s).

Anyway, since the install, the car's been running hot under most circumstances, and the six fans running, with water wetter in the system, still hasn't been enough to keep it cool in traffic in summer with the A/C on.

I was thinking of trying to build a 928Motorsports style air intake to try to reduce the amount of radiator surface blocked by the air intake box of the Vortech, but, after looking closer at the system, I don't think that's my real problem.

All of the electric fans are mounted directly against the radiator, with no shrouds other than the cage that's part of the fan itself. This means that the hubs of the fans, which don't allow airflow, are right up against the radiator. For the six fans, this adds up to 87 square inches of blocked radiator from one side or the other. I would think that this would tend to reduce the efficiency of the cooling system quite a bit.

I'm not sure whether I have enough room to offset and shroud both of the pusher fans... I may need to remove one and reposition the other; but on the back side, I certainly have room to back the fans up about 2/3" and shroud them with a bit of a box. What do you folks think? Would that be worthwhile, or does the hub blocking half the area of the fan not really make that much difference?

Oh, BTW, I did verify that when very hot, the louvers are fully open, and the fans are getting full battery voltage.

Thanks,
Paul

Maleficio

Watter Wetter is decent. Royal Purple coolant additive works great. I had trouble getting my engine to ever warm up last fall. It kind of worried me. Overkill on my stock motor, maybe just what yours needs.

Cosmo Kramer

My S/C car runs hot as well, I have a single 12" puller and a 16" pusher on my setup, wired to an adjustable thermo probe in the radiator. If you look in the Summit or Jegs online catalog you will see not all fans are equal. For example 16" pushers can vary from 2000 to 3600 cfm. My plan is to put the maximum CFM pusher/puller I can fit and that should do it.

SQLGuy

Hi Ted,

Yes, I know about different flow rates of fans, but I haven't been able to find anything useful about shrouding electric fans or how far away from the surface they should be mounted. The factory clearly didn't put the electric fans right up against the radiator without a shroud, so I'm not convinced it's the correct approach for generic fans either.

Cheers,
Paul

dcrasta

IMHO (and experience) you need a shroud when using a puller fan. Have you tried a 2 speed taurus fan. Search the forums someone used one and did a nice write-up on them. The Taurus fans are pretty nice flown +3000 cfm in high speed mode. I would suggest looking into those. (the SHO fans).

dprantl

For a pusher fan, no shroud is usually used. A pusher fan is usually mounted as close to the heat exchanger as possible, preferrably with no air gap inbetween.

For a puller fan, a shroud is preferrable. It will greatly reduce the inefficiency of having a fan cage right up against the heat exchanger. Also, it can be smaller in dimensions but be able to pull air from a larger surface area with a well designed shroud.

Dan
'91 928GT S/C 475hp/460lb.ft

Rob Edwards

WWMD?


EDIT: If you can do the Murf install, the flapectomy is comparatively not a big deal. If you get the suggestion that you need more/bigger fans and you HAVE to do the flapectomy, here's a thread on when I did it to my GT. It's a 2-3 hour project, max, as long as you have the car up in the air.

https://rennlist.com/forums/928-foru...-question.html

Imo000

There is no room in OP's setup for anything like that.

Same size but more efficient fans might be the only solution, but what did Murf had to say about this issue?

Tampa 928s

I am in the same boat in Florida I have tried various fans and it still runs hot.
With the S/C intake blocking a large portion the radiator I am not sure what can be done.
It is fine except in traffic with the air on this seems to be a common theme with us hot climate guys.

SQLGuy

Hi Dan,

Can you expand a bit on the "why" here? I can see not being too concerned about the dead zone when you have a 16" pusher, with a 4" hub, where the blades are going to cover 15 times more area than the hub blocks, but in my setup, the blades maybe cover 4 times the area that the hub blocks (looks like even less from the pictures).

SQLGuy

Murf doesn't include the 16" pusher fan, but recommends it be installed (which requires removing the flaps). I discussed the dual pusher setup with him, and he didn't really have any opinion on it.

I have not asked him about shrouding the puller fans.

auzivision

I'm in the same boat. Running hot with 4 pullers and 1 pusher. I haven't switched to the 3000 cfm yet, but have used water wetter. Runs warm under normal driving and hot under anything spirited even when it's not hot out. I'm most concerned about the air box up against the radiator because it blocks part of the radiator plus I’m guessing it adds heat to the charge.

Cosmo Kramer

What I was told is if you are mounting pullers without a shroud you mount them as close to the rad as possible. With the shroud space them back to allow them to pull air through the larger surface area.

I could see you having heat issues with just the 4 small pullers and no pusher. You may have to add one.

S4ordie

Will one of the aftermarket radiators fit in front of a Murf kit?

auzivision

Both Brian and Davids have had failure with after market radiators.

https://rennlist.com/forums/928-foru...-2-cooler.html

https://rennlist.com/forums/928-foru...stage-iii.html

https://rennlist.com/forums/928-foru...adiator-3.html

I bought Davids old C&R with the hopes of figuring out a way to modify it with a little 'forward tilt'.