Effective cooling?

illfish · Post by **illfish** » Sat Mar 21, 2009 1:38 pm

Pretty straight forward. Running a Be Cool radiator with 2 electric fans (pullers) side by side. Big B and M tranny cooler in front of the radiator.28,000 gvw. Motor is all aluminum big block. Running warm, 190 to 220 with the setup. Given the CFM is appropriate for the fans (it is), would I be better off with a mechanical fan? I never had a problem on my motors until I went to electric fans. Do they block too much surface area on the radiator? Motor is 11:1 hemi. 70/30 mix. Street car. I can afford to lose a few horsepower with a mechanical:). 30 degrees total timing. 1000cfm 4150. INDY stuff.

beth · Post by **beth** » Sat Mar 21, 2009 1:50 pm

Is the mix 70/30 coolant/water? If it is that is too much coolant for proper cooling. 30 degrees timing is not very much for part throttle street driving. Is it at least locked at 30 so it never goes below 30? You might want to research an electronic advance during high vaccum conditions.

I am not familiar with those fans but an original hemi type fan clutch and fan would probably do a better job than most electric fans. I would stay away from aftermarket mechanical fans having had one explode on a BBC before.

illfish · Post by **illfish** » Sat Mar 21, 2009 1:56 pm

I have the timing locked out at 30 degrees. On the dyno, the motor didn't like much more than that. I think the coolant mix may be too far towards the antifreeze. I'm just thinking that a mech. fan might work better and give me peace of mind. Not sure if the clutch fan would be best. 6500 rpm redline. Maybe?

beth · Post by **beth** » Sat Mar 21, 2009 4:40 pm

I have used OEM GM fan clutches and Fans to 7500 with no problems.

At part throttle the air fuel mixture burns much slower than at wide open throttle. If the timing advance is not enough for part throttle operation the mixture will burn when the piston is far down the cylinder exposing the cylinder walls and exhaust ports to excessive heat. It's easy to see if this is contributing to the problem by setting the timing to 35 to 38 degrees and taking it for a drive around town. Do not use more than 1/4 throttle or load the engine up hills etc. with this timing. If it runs much cooler you need some kind of vacuum advance (mechanical or electronic) that will allow more timing at part throttle but return to 30 degrees when the engine is loaded or wide open.

fastvette · Post by **fastvette** » Sat Mar 21, 2009 4:45 pm

I agree, you need more timing for part throttle driving.

miniv8 · Post by **miniv8** » Sat Mar 21, 2009 5:42 pm

Are you using a thermostat? If not, put one in.

illfish · Post by **illfish** » Sat Mar 21, 2009 6:08 pm

I've got a MSD billet dizzy, 6AL with timing computer,etc. I was told that being locked out with the auto trans was the way to go. Should I go back to spring advance in the dizzy? I'll definitely up the timing if that helps.

beth · Post by **beth** » Sat Mar 21, 2009 6:34 pm

You don't want to go back to spring/weight mechanical advance. Does the dist have vacuum advance capability? If it does that is what you need. If not you may be able to use your timing computer. Is there a way to set the advance for 30 degrees cranking, 40 degrees 0 to 2500rpm and 30 degrees 2500+ ? I assume your convertor is at least 3500?

Whatever you do don't just bump the timing past 30 if the dyno is calling for 30 degrees.

RW TECH · Post by **RW TECH** » Sat Mar 21, 2009 6:56 pm

How cool do you want it to run?

If it goes to 220°F and doesn't climb I don't see where you have much of a problem.

If you want to put a fan on it, use the 4-blade fan like Ford used on some of their older production vehicles - it pulls a T-O-N of air.

Keith Morganstein · Post by **Keith Morganstein** » Sat Mar 21, 2009 8:05 pm

My recipie for a big block corvette with headers that finally solved a difficult overheating problem was. Big Flexalite plastic fan, use of restrictor discs instead of thermostats - start with the middle size one and raise the rear of the hood 1/2 inch.

Similar things have helped many others: the powerful fan, restrictor discs and more air movement under the hood.

Generally all three parts together has made the solution.

MadBill · Post by **MadBill** » Sat Mar 21, 2009 8:32 pm

A couple of other tips:
o Make sure the grill opening is sealed to the rad, so that air can't 'detour' around the core. I found some plastic material which looked just like corrugated cardboard that worked very well.
o A spoiler of some sort below the bumper will usually deflect more air through the rad while creating a low pressure area behind it. I found an inexpensive roll of 5" wide plastic garden edging that worked well and would survive contact with parking curbs, etc.
o If you try raising the back of the hood, tape a few wool tufts along the opening and see which way the wind blows. Most times I've tried this the air flowed in rather than out, thus pressurizing the underhood area and reducing rad air flow.

D.Cecere · Post by **D.Cecere** » Sun Mar 22, 2009 7:08 am

Ensure you are getting correct voltage to your fans, ensure your alternator is supplying enough power otherwise your fans will not be spinning at designed rpm. Also check direction of fan rotation is correct.
Had a very similar problem on a customers vehicle....fans were not getting enough power and were not wired with a relay in the circuit.

LM406 · Post by **LM406** » Sun Mar 22, 2009 8:51 am

Are the fans mounted in a shroud that covers the entire rad or are the fans attached to the directly to the rad using the crappy plastic clips leaving surface area unused.

MadBill · Post by **MadBill** » Sun Mar 22, 2009 10:16 am

Are we talking high temps in stop 'n go traffic, or over say 40 MPH? If the former, remarks about fan efficiency apply. If the latter, rad ducting, core size and fin/tube design or damage are more relevant

Steve Smith · Post by **Steve Smith** » Sun Mar 22, 2009 11:23 am

I went nuts chasing an overheating problem until I found a lower rad hose collapsing on a competitors car. That's when the lightbulb finally lit and I replaced my hoses with alloy tubing. Problem solved!