bigvette1

I run a 73-454 with engine mods. I have the stock radiator, shroud, fan and fan clutch, high flow water pump etc. all of which are in top shape. I installed a 16" aux. fan as a puller inside the radiator for extra cooling.

I think once the engine heats up and the extra fan kicks in via the temp control unit set to 190, it actually gets hotter instead of adding to the cooling of the fan and fan clutch. Yes, it is a puller and is wired correctly and has the blades in the right direction.

MY THEORY - I think the extra "cooler" air drawn across the radiator by the fan reduces the temps low enough so that the fan & fan clutch does not "clutch-in" and stays free wheeling. This results in less cooling as the fan & fan clutch are not "locked" to pull max air.

Has anyone experienced this situation? Thanks.




[Modified by bigvette1, 3:19 PM 8/28/2003]

adamdinat

I thought the clutch driven fan on the engine RPM driven kicking out with too much drag. The only thing I can think of is that you may be causing a restriction with the new fan and mounting bracket? What is the CFM of the engine fan?

bigvette1

The clutch is a thermal activated unit. Maybe RPM's come into play. I think when the temp gets to the preset it "clutches in" vs free wheeling and draws more air.

Yes, I have thought that the puller fan inside the radiator is blocking air, but not too much. It is a 1500 cfm fan. Thanks.


[Modified by bigvette1, 3:30 PM 8/28/2003]

mrvette

Big, you need take that electric fan out, I don't think there is much of any combination other than a dual Spal setup on one of Tom DeWitts radiators that will successfully cool a BB in a shark.....you need a double row radiator, nice secure tight fitting shroud, and two healthy fan motors, you gotta MOVE some air....
you sure you clutch fan is right??? is it a 7 blade fan??? full diameter???
you may want to try the largest diameter 7 blade flex fan you can find....it's cured many a car in the past, radiator be damned....

GENE

bigvette1

Gene, I have to agree with you on the cooling. A BBC in the vette that is more than stock makes some serious power and some serious heat.

Eventually I want to go the DeWitt and Spal route, but all the $$ are gone now in the engine.

The stock fan is a 17 1/2" 7 blade fan with a replacement fan clutch that seemed to work ok. I just think the extra fan is cooling the clutch to the point it spends more time free wheeling than clutched in and pulling large amounts of air. Thanks again Gene.

Fevre

Crazy theory, the clutch fan is not pulling as much cfm as the elec fan so there is a bottle neck between the elec fan and the clutch fan so the hot air drawn from the elec fan is 'trapped' in the shroud area and might even be pushed out the front of the rad through where the elec fan isn't covering. Damn that is :crazy: . Believe aux elec fans are usually installed as pushers in front of the rad. If it runs cooler without the elec fan running yank it out of there.