Fabricating Custom Alumnium Fan Shroud...Overheating - Third Generation F-Body Message Boards

CamarosRUS · 09-26-2009, 07:39 PM

"Custom" 383 runs hot; very hot in traffic and won't cool back down when it gets hot.
Upwards of 260 degrees, maybe more if I let it idle long enough. Bottom air dam is in place, car runs cool on a cool night cruising in the country away from traffic.

Running single 16" Proform fan 2100CFM
http://www.summitracing.com/parts/PRO-67016/

JEGS 31x19 2 Row 1" cores aluminum rad (555-52009)
http://www.jegs.com/p/JEGS/JEGS-Univ...52961/10002/-1

Stewart Stage II Reverse rotation water pump

Wanting to fabricate a shroud since I am not currently running one. Any tips?
I read you should have 1.5-2" between the shroud and radiator core. The fan sits 1/16th" off the radiator core.

Hopefully this will solve my issues. If not I will purchase a second fan to act as a pusher as well.

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8t2 z-chev · 09-26-2009, 08:27 PM

A shroud will help a little,but the main problem is that
fan is just too small-those thinline fans with thin,shallow
pitch blades just don't move much air-a stock single
electric will have quite a bit more airflow,a higher power
fan should cure the problem.

CamarosRUS · 09-26-2009, 08:35 PM

Thought about getting a more quality fan for the puller, using this one as a pusher, and fabbing up a shroud but this fan claims 2100CFM....that's quite a lot!!?!?

one92rs · 09-27-2009, 09:25 AM

from my experience thise thinline fans pull that much without being mounted. when they are mounted to a rad. they pull a lot less. and the proform fans have given me trouble before. i would look for the better fans if it were me. flexalite or derale have given me trouble free service for years.

CamarosRUS · 10-01-2009, 10:27 PM

I'm going to try the shroud thing and see what that does.

What about this? Am I just wasting my time making a "box" shroud like this. It will be approx 1.5" deep. I don't know if I can get any more out of it due to the pitch of the rad...the shroud will hit the bottom tray if it is much thicker.

I don't have the skills to radius and funnel the shroud.

8t2 z-chev · 10-02-2009, 08:15 PM

well worth a try-you can always adapt a larger fan to it if
the fan you are using is too weak

CamarosRUS · 10-03-2009, 01:50 AM

Well I'll be using a 16" fan so I can't really go any bigger but maybe a little bit better....and also run a second pusher fan.

CamarosRUS · 10-07-2009, 09:39 PM

Thinking about a pre-fabbed shroud from JEGS. Its only 1/2" deep, however.

Any thoughts on that?

deadbird · 10-07-2009, 10:45 PM

Quote:

Originally Posted by 8t2 z-chev

A shroud will help a little,but the main problem is that
fan is just too small-those thinline fans with thin,shallow
pitch blades just don't move much air-a stock single
electric will have quite a bit more airflow....

...against the resistance of drawing air through the radiator.

The shroud isn't the problem...

The fan you have shown in your post would do good to draw air through a screen door on your house, let alone a radiator and a/c condenser.

Thin pitched bladed fans are not good at drawing or pushing air against resistance. In general, a bladed fan period is poor at doing that. A mech fan does better because it can use a high pitch (like a big 440v warehouse fan) because it's power source is the HP from the motor. It's also placed further back and the shroud acts as a venturi in a way.

There is a good reason why the electric OE fans run a good amount of amperage (or even aftermarket), have a fairly high pitch on the blades and most important, have the venturi ring around the blade tips if they don't have a shroud.

Granted, that's just one's opinion...

CamarosRUS · 10-08-2009, 07:03 AM

Nice post. I have a used SPAL 16" straight blade fan coming from eBay. Don't know much more than that but being SPAL it has to perform better than my Proform, correct?

Not wanting to run a mech fan, what are my other options (also cannot drop $150 on a fan).

deadbird · 10-08-2009, 10:03 PM

I wish I had a real aftermarket fan answer for you but, I've never had a problem to date using junkyard OEM fans for any of my cars.

My '91 is currently running a single fan from a 94 Gran Prix and actually works better than the original fan.

I ran 2 v6 dodge dynasty fans onf mt 3/4 ton '76 suburban with a 400ci without any issues.

I have a 16 flex-a-lite fan on the 71 and it will overheat just idling for the 15 mins I have to **** with the p.o.s holley on it (long story in the pre flight tune to even start the heap).
While you can feel the air from the engine bay side, you can't feel the air draw from the front (pulling air through the radiator) like you can with the GP fan on my 91. Blade pith on the GP fan and venturi ring are the difference. The '71 obviously isn't an A/C car either (though was an option for the year).

CamarosRUS · 10-08-2009, 10:08 PM

I think I may have tackled the issue by bumping the timing to 20* initial and 34* total. Won't know fo sure until I can drive it but I would still like to run a shroud...just can't justify $90 for sheet aluminum if I don't really need it.