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  #1  
Old Apr 10th, 13, 04:11 AM
Big Dave Big Dave is online now
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Default Keeping Your Cool

I am frequently asked about radiators; size, as well as what is better aluminum or copper?

Since all radiators have the same tanks on the end (well there are two styles of tanks with a transmission cooler and those without if you have a manual trans) you do not measure the tanks. The radiator is sized only by the core.

There are three different sizes for a stock radiator in terms of length, a six cylinder (19 inch), small block V-8 (21 inch), and big block V-8 (23 inch). That isn't how they are actually sized, but how it breaks down with stock engines. Radiators are actually sized the same way your air conditioner is at home, in terms of BTU's. Since one third of the engine's rated capacity is shed as heat, there are three different size radiators based upon the horse power ratings of the engine. So you can see the relationship between the six and small block and the big block.

Where this classification breaks down is where you have a small block that makes as much power as a stock big block. It still needs the big block size radiator. There are also differences in the number of cores based upon extra heat loads placed upon the system such as living in a hot climate or behind another heat source such as air conditioning that pre heats the ambient air temperature up before the radiator sees it.

This is why the factory offered HD cooling as an option (RPO V01). This option was included automatically if you ordered air conditioning, or if you had a high horsepower car engine such as was included in the SS package. You could order HD cooling as an option even for an under powered six cylinder if you lived in a hot climate like the desert southwest (Death Valley for example).

You really wouldn't want to be stranded by an over heated car there, so car buyers who lived there learned early on to order the HD cooling option when they bought their cars from the dealership. The HD cooling option added extra cores to make the radiator core thicker to shed more heat to the air passing through it. This option also had a radiator with a higher fin count per inch if you had an oil cooler for an automatic transmission installed in the radiator tank.

So in conclusion the biggest (which in terms of radiators is the best one to buy) is a BBC radiator, with air conditioning, that also had an automatic transmission. The outlet neck is different on a BBC (straight instead of bent at a 45 degree angle), but you can use a BBC radiator upper hose (it has a 45 degree bend in the hose) on a SBC and it fits perfectly. So if you buy the BBC radiator expect to replace the upper hose (I would swap out both for new ones). Which takes care of the size question.

Aluminum or copper?

Copper cools better than aluminum because it conducts heat and electricity better than aluminum. Where aluminum shines, is in it's strength of construction. Aluminum radiators are welded together, not brazed together with a lead based solder the way a copper radiator is. Copper is so soft it has to alloyed with tin to make yellow brass. Because you have different metals you can not weld it together, it has to be soldered and the metal they use is softer and weaker than the base copper. This is why most radiators fail. The soldered joint leaks due to work hardening the soft solder. Aluminum is also much cheaper than copper which is why all of the manufactures have gone to an aluminum core radiator with plastic tanks glued on. They claim aluminum is lighter and saves fuel (that is a true statement), but the real reason is to save money.

Because aluminum is so much stronger than copper you can raise the pressure in the radiator by changing the spring in the radiator cap. This higher pressure allows the coolant to run hotter without boiling which prevents detonation in the motor. When the coolant boils you get steam which doesn't conduct any of the heat out of the engine; so you get hot spots that allows detonation to occur. This is a bad thing. If you have a high pressure cooling system (allowed with welded aluminum) you can run higher pressure in the cooling system. Higher pressure reduces boiling which lowers the octane requirements with modern unleaded fuel that has no octane rating compared to what was burned when these old muscle cars where new.

The only fly in the ointment is your heater core is still a brass-copper soldered assembly. It will blow apart if you run a higher pressure cap than the factory rated one. So you have to replace both the heater core and the radiator to run a higher pressure cap which is what modern cars and trucks have done.

If any one can find a late model aluminum heater core out of any modern car (even an import) that will fit in our heater boxes let me know by posting that information here. That way we can all upgrade both the radiator and the heater core to aluminum to keep our cars safer from detonation.

Big Dave
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  #2  
Old Jul 1st, 13, 09:43 PM
ruffy ruffy is offline
 
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Default Re: Keeping Your Cool

So, if I decide to put an after-market a/c into my 77 Nova, with a 305 ci, will I need to consider changing my radiator?
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  #3  
Old Jan 5th, 15, 04:32 PM
vt69nova vt69nova is offline
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Default Re: Keeping Your Cool

Dave,
I just posted a question, guess I should have read here first!!!!!! THANKS FOR THE FYI on the hoses!!!!
Million dollar question, can you use the SB fan shroud on a BB radiator or is it ok to use the BB shroud with a 350?
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  #4  
Old Jan 5th, 15, 04:39 PM
Big Dave Big Dave is online now
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Default Re: Keeping Your Cool

BBC fan shroud on a Nova is offset by an inch so no they are not interchangeable.

Big Dave
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  #5  
Old Jan 5th, 15, 06:59 PM
vt69nova vt69nova is offline
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Default Re: Keeping Your Cool

So dave,
I had taken the mounts off the front cross member and put SB mounts in place. So it would be ok to have left the BB mounts in for the 350? Also using the BB Shroud? Sweet.
So at this point, all I would need to change is my SB clutch linkage?
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  #6  
Old Jan 13th, 15, 09:40 AM
[email protected] Justin@EntropyRad is offline
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Default Re: Keeping Your Cool

Guru-worthy post..glad this is a sticky!
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  #7  
Old Feb 24th, 15, 07:22 AM
57-Z06 57-Z06 is offline
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Default Re: Keeping Your Cool

Dave, I have a base model Nova that came stock with a 307 V8. I plan to use a large crossflow radiator, so my question is this; will I need to change the radiator core support to a "big block" model, or will the large crossflow radiators work with the stock core support? Thanks in advance.
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  #8  
Old Feb 24th, 15, 08:50 AM
Big Dave Big Dave is online now
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Default Re: Keeping Your Cool

Quote:
Originally Posted by 57-Z06 View Post
Dave, I have a base model Nova that came stock with a 307 V8. I plan to use a large crossflow radiator, so my question is this; will I need to change the radiator core support to a "big block" model, or will the large crossflow radiators work with the stock core support? Thanks in advance.
For the additional area of the bigger big block radiator to work it must be exposed to air flow. This requires a larger hole. That is the best way of cooling a larger horse motor since heat load rises with horsepower.

The second best way that doesn't require a bigger hole is to go with a thicker core area. In NASCAR racing where aerodynamics requires a small frontal area they use a C&R, or Ron Davis radiator that is four to six cores thick As opposed to three to four on a stock radiator. They can obtain the same results (cooling a 750 to 800 horsepower small block engine) because they are averaging 130 to 150 miles per hour depending upon the track. That air pressure that builds up in the front of the car forces air through the ticker radiator cooling the engine.

On the street you depend upon a big mechanical (an 18-1/8th inch in diameter for a car and light truck with 5, 6 or 7 blades depending upon the motor and A/C being an option) to move air over the radiator below 45 mph. As the core becomes thicker (such as installing an A/C evaporator and an automatic oil cooler in front of it), or by adding cores the resistance to air flow exceeds the ability of just one fan to move enough air to cool the motor.

The solution to this problem is to add a second electrical powered fan in front of the radiator to push additional air through the radiator. I would point out if you are going to add an electric fan to cool a thicker radiator and it is thicker because you added a big transmission oil cooler why put it in the front of the car? You can locate the electric fan and oil cooler anywhere on the vehicle there is a supply of ambient temperature air. I use a pair of long thin oil coolers attached to the frame rail (I had a 582 BBC in a 1985 Impala that was the same size and weight as a 1970 Chevelle, but no one would confuse the two cars, or expect anything at all out of the 1985 Impala other than it being a worn out Taxi). In a Nova with frame connectors you could mount it onto the out side edge of the frame connector and free up the added heat to the air going through the radiator.

Big Dave
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  #9  
Old Feb 24th, 15, 09:22 AM
57-Z06 57-Z06 is offline
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Default Re: Keeping Your Cool

Thank you Dave. I very much appreciate your time and knowledge.

Ray
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  #10  
Old Aug 10th, 15, 11:00 PM
GBJ GBJ is offline
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Default

Dave, when I put my a/c in I put a PRC double pass radiator only no trans cooler and a Spal puller fan. When I put my 700R 4 in a few weeks ago I put a Derale 13900 trans cooler with a puller fan and 180 degree thermostat. Also 2" Goodmark cowl hood. I went from 3400 rpm at 70 mph to 1800 rpm in 4th gear lockup. My question is my engine temp did not change, 100+ heat index on the TX/LA coast this time of year. I'm running 190 degrees on highway and climbs to 200/210 in slower traffic. I've tried various water/glycol mixtures, water wetter and no change. Right now I'm with one bottle water wetter, half gallon glycol and the rest mineral water and running the temps above. I know my little short stroking 327 adds to this. My biggest concern is the underhood heat on the other components, alternator, belts etc. Of course with stock shock tower's it holds even more heat. Can the heat from a puller fan increase engine temp? I've been thinking about cutting slots in the shock tower's and other areas in order to let some heat out. I know pullers are more efficient and with a big condenser in front of the radiator a puller is the best bet but would love to figure out a way to lower traffic temp and get some of that heat out of the engine bay.

Thanks as always,
George
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  #11  
Old Aug 11th, 15, 07:54 AM
Big Dave Big Dave is online now
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Default Re: Keeping Your Cool

You are fine. Modern cars have a 224 thermostat and under hood temps are even higher. If you put a cheap dial meat thermometer on your hood by the windshield you could measure the temp of the air coming out of your engine compartment.

I say this because unless you have a flat under hood with a circular hole in the underside for the air cleaner to go through and then seal it with foam; all your hood scoop is doing is allowing more hot under hood air to exit your engine compartment by way of the scoop. Theoretically this will improve air flow through the radiator by lowering the friction to air trying to leave under the car.

The only thing you might want to try is an air dam under the chin to force more air through the radiator at a lower car speed. But other wise you are having air flow issues due to using an under powered fan not being able to move air at idle. There isn't an electric fan combination made that can move as much air as a factory mechanical fan with a shroud can.

Big Dave
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  #12  
Old Aug 11th, 15, 03:37 PM
GBJ GBJ is offline
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Default Re: Keeping Your Cool

Big Dave, do you or anyone else on the forum know anyone or have used a front air dam from Spoilers by Randy? Heard good and bad like always. Here is a pic of the plain spoiler, he has a pro touring spoiler also but it's to big for my taste. Just looking for another toy and if it adds cooling that's a bonus.

Thanks,
George
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  #13  
Old Aug 11th, 15, 08:10 PM
Big Dave Big Dave is online now
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Default Re: Keeping Your Cool

That's what you are looking for in a chin spoiler to drive air into the radiator at speed. You can also find them lying in parking lots where people knock them off of modern cars while parking by ear.

Big Dave
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  #14  
Old Aug 11th, 15, 08:35 PM
brian oneil brian oneil is offline
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Default Re: Keeping Your Cool

I got a 2005 Monte Carlo, and I smack the chin spoiler on that car into the parking blocks all the time. Luckily it is still on the car
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  #15  
Old Aug 12th, 15, 03:38 PM
GBJ GBJ is offline
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Default Re: Keeping Your Cool

As I noted if it provides any extra cooling that's just a bonus, I happen to like the way it looks in that small of a version. Just asked if anyone has heard of the guy building them. Purely cosmetic. To each his own.

Thanks,
George
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