Thread: underhood heat management

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I'm having a few issues with underhood heat in my BBC powered S-10 Blazer. I have a good Griffin radiator and 3 Spal 10" e-fans and an aluminum water pump. I currently do not have inner fenderwells and a stock flat hood. The engine runs fine and keeps relativly cool when driving. I do have a problem with the front brakes getting very hard and seizing the calipers when temps start to rise. If I open my hood and let the engine run the temp will go from 215 to 195 fairly quickly, so I'm guessing that the under hood air is overheated. This superheated air can not be good for horsepower either.

I've considered making some inner fenders to help keep the heat from the headers out, but what can I do about the heat from the radiator? Would some sort of NACA duct in the hood help? I know a bit about aerodynamics from some college courses, but I'd like other opinions.
Here is a link to what I mocked up today, as you can see space is limited.

http://www.cardomain.com/ride/753520/6

Maybe a cowl induction hood is in order. I'd like to use the flat hood for the sleeper look. I could possibly duct cool air from the area where the wiper rods reside in the cowl. How do I get all of that hot air out from under the hood?

I plan on adding a few ponies this winter and don't want to compound the problem. I was going to build a 540, but I'm broke. So I think I'm going to just change to some domed pistons so I can use an aftermarket aluminum head.

Oh yeah.

BTW - after I drive for a while the whole front of the Blazer gets so hot you can't touch it.

get a scoop of some sort, cowl induction could also work. also a small duct type thing from under the bumper leading up wouldn't hurt.

You know how in the front bumper people put those god lights there? I say put two 3" diameter holes on eachside of the bumper with the duct stuff into the compartment. Hard to explain and I dont mean to leave just holes, I mean put metal tubing behind like it's a metal hole going in and all smoothed out and nice. Make them point up and have the air blow on the motor and taking the heat since they will be pointing up and back and it will shoot more air through the cowl. See what i mean?

You've got other issues if you're siezing brake calipers. They should be able to operate at temperatures well over 300 degrees.

Getting your headers ceramic coated will drop your temperatures considerably. Wrapping them with a header wrap will drop them even more. There have been some issues with wrapped headers cracking, but if you've got access to a welder so you can repair your headers, I would give it a shot.

Is there a splash pan from the bottom of the rad to the bumper? Hot air circulating under (or over) the radiator will be drawn back through the rad, causing heating at low speeds. I agree that engine heat won't bother the brakes, you've got other problems. Is there a residual pressure valve in the front brake circuit? If so, remove it.

OK, I looked at your pics. Those cardboard fender liners would be better if they didn't go all the way to the firewall, there has to be somewhere for all that hot air to go. Louvers would work. Don't duct the heater plenum into the engine compartment. That's OK for carb air, but not enough flow for cooling. Besides, S10's don't have any way to shut off air flow through the heater duct, you'll get heat coming in all the time. If it's a fairweather cruiser you can delete the heater/AC, but in the real world, that ain't an option.

I have Earl's stainless flex hoses to the calipers. When it happened last time I was going to the track and about 3/4 of the way there the pedal got so hard I could barely push it. As I was waiting to get in to the track I could see the smoke rising from the calipers and hear what sounded like the fluid boiling inside them. I have a factory manual brake booster and SSBC Force 10 calipers on factory discs up front. When the bleeder was cracked open nothing came out? This problem is very confusing. I also lost all fluid pressure to the rear brakes, so maybe the heat damaged the master cylinder and/or Wilwood prop valve too.

The cardboard was just a little brainstorm I had on a lazy afternoon. I was going to fabricate some ducting from the cowl area and a air box for the carb, but instead got sidetracked. I also started making some templates for some steering stops. I'm afraid of blowing a tire from them rubbing on the headers.

I have some header wrap in the shed. I've used it before. I was trying to avoid using it because the headers rust much more quickly. After I first installed the small block I wrapped the Hooker long tubes and they damn near disintigrated after 2 years. I am going to get the outsides of the headers black ceramic coated over the winter. If I add another 100 hp with a piston and head change then there will even more heat to deal with.

get the brake lines away from the headers i think thats is the brake deal. make some alumimnum heat sheilds leave some are gap for a heat boundary for the brake line with out the inner fenders in the heat may be getting push down and not out down on the lines. i have built header for small block S10 and the line on the frame get close on the drive side keep the brake lines at least 3inch or more from any header tub the master could be getting hot heat will rise to. but i would work on the line the heat may not be getting out were you think try a house fan in front of your S10 and you can find were the air is moving put a piece of yarn on a stick and move it to find the path of air movement

im sorry a big block ??? that thing must get hot on the frame with all that engine sitting on top of it look at the lines on driver side i think they need to be moved big engine small engine compartment had the same thing with my 548 blown 50 chevy the gas was getting hot all this fits under the stock hood but with the small compartment air dose funny things and my car runs hot some times to so i took the hood off .this did not do any thing i made a air dam is did not do nothing at the end of this i think the air can not get out were i want it to go so i am going to open up the core suport to try to get force more air movement thur the engine compartment this may help you

If by "open up the core support" you mean make holes beside the rad, you'll just make the problem worse allowing air to bypass the rad. The hot air has to get out after going through the rad.

may be may not if all you have is hot are under the hood it will go up not out so there is not much you can do if you have a small grill open it up with let say two 4 inch holes can not be to bad the way it was from gm on the 50 chevy for the heater intake this was the way my car was and did not get hot till i weld the core sport closed and it seams to get hotter yes it has to get out to but heat will rise to ? in my case i have inner fenders he dose not so in his case this may work in my case i may have to puch holes in my inners thats why i said try the the house type fan to see air movement .after saying all this i do not have all the answers but i had a 66 gtobig block 1/2 filled with block filler bored out to 477 13to1 with no fan on it no core support or inners and it seam to work good it had a small gm electric fan on it .my land lord builds aro batics air planes and i have talk to he but he has not much to say on this and i think he know what air will do. but he has told me it is not that easy. so ???

You don't need to get more air in . You need to get the hot air out. I went throught this with my Willys Station Wagon. Ended up grafting in hood louvers from a (gasp) Honda Accord. Solved my problem.

Originally posted by 53 Willys
You don't need to get more air in . You need to get the hot air out. I went throught this with my Willys Station Wagon. Ended up grafting in hood louvers from a (gasp) Honda Accord. Solved my problem.

I agree with getting the hot air out. Punch the hood full of louvers or make some spacers to space the back of the hood up 1-2 inches so the air can escape.

no this may help S10 but read what i did have the hood off the car and if you know any thing about a 50 chevy they are a bitch to get the hood off when it all black and shiny this thing has hood spring from hell and hook to the bottom of the cowl and catch at the top of the spring i made a tool for this. i lost all my friends on this . you my be rigth but this car is way way to nices to jack the back of the hood up and there is no way it will work on the 50 chevy hinges they are not like the gm newer hood hinges heat will need to come out and i know heat will rise but i think of this like a box with to small of a hole in front like a pice of plywood in front of your rad. i do not know? so i think it may need some louvers in the inners just not to sure this is. the way to go by it. the cowl i have a lot of places for hot air to get out but the air under the car may not let the air out of the hood to slow air speed that is why i put the air dam on it and did not work thanks for bouning it off you guys more cool air in the carbs is what i think is what i need to help .with the super heated air so some more air in were it is not running thur a hot rad is what i need have lived with it this way for 4 years just not ready to start cutting in to it when i spent all the time pluging all the holes :

I agree with those that said you need to get air out of the engine compartment. To cure the problem with my Studebaker, made vent holes in the inner fenders to let the air out. Weeg had an even better idea for his. He is putting vents in either side fenderwell and mounting an oil cooler on one side and trans cooler on the other, then putting a sucker fan on those to pull air out of the engine compartment across the coolers. If the air is kept moving well enough it should be cool enough for the coolers. Another alternative is to leave the coolers out and just put sucker fans behind the vents that you can control. The vents would dump into the wheel wells where the hot air should be able to escape.

I also agree with the ceramic coating, the Jet Hot people promise you will see a major drop in temperature and the cost is not outrageous, they perform better, look great and last longer too.

http://www.jethot.com/

good luck!

Pat