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Discussion Starter · #1 · (Edited)
Have not had the 57 out in quite a while. Let it idle outside to let the engine come up to temp, hood closed. I have a nice Be Cool crossflow rad. with an electric fan controlled by a 170 deg. (on) sensor at the thermostat housing. By the time the fan comes on, the underhood temp. is scorching. No airflow until the fan comes on or going down the road. Actually blistered the paint on the bottom of the brake booster. (will start another thread on that). Headers are about 6" away.
I will not let it idle sitting still again but need some suggestions.
I forgot to add that the engine temp stays at 180/190 deg. with fan on.

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Have not had the 57 out in quite a while. Let it idle outside to let the engine come up to temp, hood closed. I have a nice Be Cool crossflow rad. with an electric fan controlled by a 170 deg. (on) sensor at the thermostat housing. By the time the fan comes on, the underhood temp. is scorching. No airflow until the fan comes on or going down the road. Actually blistered the paint on the bottom of the brake booster. (will start another thread on that). Headers are about 6" away.
I will not let it idle sitting still again but need some suggestions.

Thanks
I have a 383 in ours and have an overheat issue whenever we turn the a-c on. We have a custom aluminum radiator with 185 degree (on) electric fans. The problem remained no matter what we did until I removed the hood. No more overheat problem. That told me that the radiator was getting rid of the heat but the engine bay was trapping it. I'm taking my spare hood in today to get some louvres punched at the back of the hood, near the base of the windshield, that hopefully will ventilate the engine bay enough to resolve that issue. We'll see, but it looks encouraging.
 

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I'm taking my spare hood in today to get some louvres punched at the back of the hood, near the base of the windshield, that hopefully will ventilate the engine bay enough to resolve that issue.
Have a glance at this thread here. @55 Tony pulled their hood seal and ended up getting all the hot air inside the car instead through the cowl vent.

I'd probably start with addressing the major heat source and coating, or even coating and wrapping the headers to reduce the heat load being added to the engine bay in the first place. If you're blistering paint, that's more than a little airflow needed IMO.
 
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I have a 383 in ours and have an overheat issue whenever we turn the a-c on. We have a custom aluminum radiator with 185 degree (on) electric fans. The problem remained no matter what we did until I removed the hood. No more overheat problem. That told me that the radiator was getting rid of the heat but the engine bay was trapping it. I'm taking my spare hood in today to get some louvres punched at the back of the hood, near the base of the windshield, that hopefully will ventilate the engine bay enough to resolve that issue. We'll see, but it looks encouraging.
At speed there's a high pressure area at the base of the windshield, and that's what cowl induction is all about. You might end up with more air build up. But then it might force the air out the bottom so who knows? Good luck with that experiment, and please report the results.
 

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At speed there's a high pressure area at the base of the windshield, and that's what cowl induction is all about. You might end up with more air build up. But then it might force the air out the bottom so who knows? Good luck with that experiment, and please report the results.
Actually it's a LOW pressure area at the base of the windshield. A while back I taped pieces of yarn all over the hood and windshield and took it out for a spin on the freeway. The yarn at the front of the hood and the top of the windshield revealed the expected airflow, but the yarn at the bottom of the windshield pointed toward the back of the hood and the yarn at the back of the hood was pointing toward the front of the hood, the reverse of what I'd expected. The body lines on newer cars would probably have a much different airflow, but the tri-fives are so boxy that the airflow isn't what you'd think.
 

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Actually it's a LOW pressure area at the base of the windshield. A while back I taped pieces of yarn all over the hood and windshield and took it out for a spin on the freeway. The yarn at the front of the hood and the top of the windshield revealed the expected airflow, but the yarn at the bottom of the windshield pointed toward the back of the hood and the yarn at the back of the hood was pointing toward the front of the hood, the reverse of what I'd expected. The body lines on newer cars would probably have a much different airflow, but the tri-fives are so boxy that the airflow isn't what you'd think.
I think you actually proved the high pressure area. The air at the base of the windshield curls like an upside down surf wave, and heads back towards the front of the hood. A rearward facing scoop grabs some of that air, and is forced into the air cleaner if it's sealed like in a cowl induction setup.

Smokey Yunick used that to an advantage in the 67 Chevelle race cars he built, except that he used no scoop. He fed air from the cowl vent straight to the sealed air cleaner.



 

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Do you have headers they generate lots of heat
 

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I think you actually proved the high pressure area. The air at the base of the windshield curls like an upside down surf wave, and heads back towards the front of the hood. A rearward facing scoop grabs some of that air, and is forced into the air cleaner if it's sealed like in a cowl induction setup.

Smokey Yunick used that to an advantage in the 67 Chevelle race cars he built, except that he used no scoop. He fed air from the cowl vent straight to the sealed air cleaner.



We'll see in a bit. I took my spare hood in for some louvres earlier today. When I get it back and mounted I'll put some yarn in the louvres and see which way it blows. Into the engine bay; high pressure area. Out of the engine bay; low pressure area. :)
 

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This is really no different than any other electric fan auto, literally almost a billion of them out there.

The reason your paint is blistering off your brake booster is the residual brake fluid residue from any of the brake services preformed.

As for trying to control air flow via louvers you would be much better off installing an air dam under your radiator support so that the hot air will travel out under the car as later cars are designed. This will also improve high speed front end lift and possibly gas mileage.... Louvers in the rear of the hood are about the worst thing you can do if you want to lower under the hood temps. They will work much better immediately after the radiator, but this will also increase cowl air temp heating the interior of the car.
 

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You kind of answered your own question.

By design your engine bay had a mechanical fan that produced a constant "flow" that marginalized heat soak. When you switch over to electric fans that do not run all the time you have a static or stationary compartment that will get rather hot quickly.

A couple things to consider.

Manual transmissions with a neutral safety switch to be used as a fan switch. is a great one however does not address sitting stationary in gear.

Two speed fan circuit; A fan controller that allows a programmable set up to switch on the fans on a low speed when ever the engine is running and then be thermostatically activated to attain full speed when needed.

Simple answer is switch on your fans when the car ain't moving and the engine is running.
 

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I have several friends who've had the same issue with excess heat, and not just burning paint on the booster, but boiling brake fluid in the master cylinder!!
What they did doesn't remove the heat, but it protects the master/booster setup. They bought or built aluminum heat shields that mount to the firewall, or to the booster and sit under the master/booster to shield them from the extremely high temperatures from the headers.
Some shields only cover the master, but you can buy or make one that goes back to cover the booster also, and sandwich the two under the same mounting bolts so they are both shielded from heat.

Only way to reduce the heat in the engine bay is to make louvers, or some openings to allow it to exit. But even those don't work well when standing still, idling. So best to shield the master and booster, so they're protected.
 

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I have several friends who've had the same issue with excess heat, and not just burning paint on the booster, but boiling brake fluid in the master cylinder!!
What they did doesn't remove the heat, but it protects the master/booster setup. They bought or built aluminum heat shields that mount to the firewall, or to the booster and sit under the master/booster to shield them from the extremely high temperatures from the headers.
Some shields only cover the master, but you can buy or make one that goes back to cover the booster also, and sandwich the two under the same mounting bolts so they are both shielded from heat.

Only way to reduce the heat in the engine bay is to make louvers, or some openings to allow it to exit. But even those don't work well when standing still, idling. So best to shield the master and booster, so they're protected.

Shields only address radiant heat.
 

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Discussion Starter · #16 ·
You kind of answered your own question.

By design your engine bay had a mechanical fan that produced a constant "flow" that marginalized heat soak. When you switch over to electric fans that do not run all the time you have a static or stationary compartment that will get rather hot quickly.

A couple things to consider.

Manual transmissions with a neutral safety switch to be used as a fan switch. is a great one however does not address sitting stationary in gear.

Two speed fan circuit; A fan controller that allows a programmable set up to switch on the fans on a low speed when ever the engine is running and then be thermostatically activated to attain full speed when needed.

Simple answer is switch on your fans when the car ain't moving and the engine is running.
After losing some more sleep at nite thinking about this, I've decided on 2 things to try...
I'm putting a toggle sw. inside to manually turn the fan on untill the engine temp. sw. takes over.
Do not let the car idle before engine is up to temp. (hit the road...lol)
 

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Yes I do, and I think they are the major cause of the heat.
This is the first thing I'd address. The easiest way to get heat out of the engine bay is to add less heat in the first place. Some of the ceramic coatings reduce heat shed dramatically, some say 50%. I'd also wrap the headers if this works for you aesthetically. Wrap can increase header corrosion in cars used in wet weather, but it's less of an issue once they're coated.

As a bonus, you'll see minor power gains just from keeping the exhaust gas velocity higher and the intake charge cooler.
 
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