Thread: Aluminum vs Brass Radiator

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I have a 1940 Chevy coupe with a 350 SBC that has run hot for years. It has a Walker radiator that Walker repaired about 4 years ago so there is no stop leak in it. I have the biggest electric fan and shroud that Walker made and required a 50 amp relay. I have a 180 degree thermostat and on a cool day it runs right at 180 degrees on a VDO gauge with the sender mounted in the head.

On a hot day it isn't unusual for me to run 210+ on the freeway and if I hit a traffic back-up I have to pull off the road, lift the hood and let the electric fan cool it off back to 180. I really would like it to run cooler in stop and go situations. I also have a Stewart high flow water pump and my lower radiator hose does have a spring.

When Walker was in business they said brass cooled better while others said aluminum. I guess my question is has anyone went from a good brass radiator to an aluminum one and noticed a significance cooling advantage? I don't mind dropping the cash on a new aluminum radiator, but I'd hate to make that investment just to see no noticeable improvement.

I should note that my electric fan evolution has went from a Spal with no shroud, to a Cooling Components (Walker) with a shroud, to my current Walker fan and and I haven't really noticed a lot of improvement from the first to the last. Attached (I hope) is a picture of my current radiator and fan.

The only anomaly I can think of is my car has never had any inner fenders, which I think would allow more air circulation.

Thanks in advance for any ideas.

210-215 is normal for a sbc in traffic. 200 down the highway is perfect with todays fuel . i use aluminum radiators and have for over 30 years. never had much luck with walker. i opted to have the orig recored instead.

Add an oil cooler.

I have a 46 Ford coupe that is very similar to your 40 Chevy. When I bought the unfinished car, it came with a massive 4 core copper/brass radiator. Due to the engine being mounted a little too far forward, there was not much room for a large fan. The car ran hot from day one. The 383 stroker didn't help. It would run 190-200 on the highway and spike to 230+ before you could get off the road and to the pump at a gas stop. This constant overheating finally cooked the 383 and I had to replace it with a 350. I tried every fan and shroud combo I could fit (mechanical and electric) and nothing helped. I refused to believe the radiator was at fault, but finally decided to change it since that was the only option left.

I swapped it for the largest aluminum Griffin Rat Rod series radiator I could get in. Has two 1 1/4" tubes. I also fitted a Cooling Components electric fan and shroud. This combo just barely fits. Fan has a super powerful motor that requires a 60+ amp relay if ran in single speed mode. The car finally runs decent temps. 180-185 on the highway with AC and 200 in traffic on a hot day. Still can't run the AC in traffic though.

As I understand it, copper does conduct heat better than aluminum, but copper/brass radiators have to be soldered together with lead solder. The fins are soldered to the tubes during construction and the lead interface between them acts like an insulator. Aluminum radiators use various aluminum bonding processes to attach the fins to the tubes, so there is a more efficient heat path. Also, aluminum allows for larger tubes so there is effectively more water in contact with the tube wall.

I do have to add that much of my problem is airflow related. With the engine too far forward, air has much harder time making it through the engine compartment. I have plans to correct this in the near future, as well as fit a larger cored radiator.

We had that problem a while back, and we eventually got it pretty well sussed.
This thread may be of some use to you:

Bus is overheating.

But...we finally got to the bottom of the problem with help from a fella many many years younger than I...It's a Chev 400 Vortec LS3 donkey, which was purchased as a crate motor, but had an LS1 card in it.
So the computer was programmed to be sending the wrong messages out to the various components.
To suss that is well out of my tiny knowledge of electronics.

Good luck!

“…….210-215 is normal for a sbc in traffic. 200 down the highway is perfect with todays fuel ……”

I agree with shine that the temperature is not out of line. I would add that if you haven’t already, the first step it to verify the temperature gauge is reading accurately. The easiest way is to use a temperature gun and compare the readings. There not really all that expensive and are a good investment anyway. I normally like to measure the temperature as it comes thru the thermostat housing.

As you and Mike both mentioned I have the same understanding that brass/copper does transfer heat more efficiently than aluminum. The aluminum however allows for a more efficient tube design than brass. When you compare the tube size in a brass radiator to an aluminum one you will find that the aluminum tubes are usually a good deal wider than the brass tubes. The reason for this is that after a certain size the brass tubes are more likely to crack over time due to expansion and contraction. As the aluminum tubes can be made wider they expose more surface area to the air and the radiator itself is more efficient than a brass one.

That being said there are a few things to look for when choosing an aluminum radiator. The main thing is tube size and tube count. On brass radiators then you wanted a more efficient radiator you would look for one with more rows of tubes (i.e. going to a 3 or 4 row radiator). Now normally the tubes were smaller in a 4 row than a 3 row but the total amount of surface area was increased so the radiator was more efficient.

On an aluminum radiator look for one that will give you the largest amount of tube surface area, not the highest tube count. I normally go for a radiator with either 2 rows of 1” inch tubes or three rows of ¾” tubes.

A lot of times if you buying on-line, the cheaper radiators will list the row count but not give you tube size. I usually avoid these because when you get the radiator you will often find that you get a 2 row with ¾” tubes or a 3 row with ½” tubes.

After one experience with 4 row aluminum radiators, I avoid them like the plague. Back when I was in my El Camino phase I had ordered a 4 row with ½” tubes to the El Camino I built for my wife. When the car was done I drove it to Tucson AZ (about 75 miles away) on a 100+ degree day. On the interstate it was running about 220 degrees…..a little warmer than I like. I had new radiator I had picked up for another El Camino I was building that was a 2 row with1” tubes so I changes the radiators out. Technically I had the same amount of tube surface area on the 2 radiators, but the 2 row ran 10 degrees cooler when I duplicated the trip a few days later. I read a few different theories over the years why the 4 row radiators are less efficient, but who knows.


Basically for me I have found that a well designed aluminum radiator works better than a brass copper one. If I have any complaints, it’s that on some cars, to my eye, a shiny aluminum radiator can look out of place (lately I’ve tended to go for a nostalgia look). Although it’s generally not recommended, I’ve never had a problem using a light coat of black paint on an aluminum radiator to make it blend in a little better.


Anyway that’s my 2 cents.



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years ago my radiator guy told me that the reason my walker radiator ran hot was it was too thick. he recored my stock 47 ford radiator with a thin 3 row zcore. worked like a champ. he said that wrecker guys would come in and want bigger thicker radiators so they wouldn't overheat setting around. he would set them up with a 3 row and then not tell them. he loved it when they would bring in another one for that thicker core. the look on their face was priceless.
it's about air flow , not number of tubes. brass/copper goes out the window once you cover them in black paint. i prefer cross flow aluminum over anything else.

one more thing. you must have 1/2 in or more between your ac condenser and radiator. that's what was wrong with walkers .

The fan blade rotation speed on the electric fans can be a problem-----If the fan is not powered it will rotate at a rpm that effectively is sorta like an airplane propeller on a engine out situation---and it basicly takes up the drag coefiecant of a complete circle---so it really becomes an solid disc? BLOCKING the flow of air---
If your fan is in front of the rad, this is happening all the time----

Looking at the pic of your radiator the amount of airflow thru that is really limited by the amount of visable fin that you can see between the blades----------

Ok I'm posting this again, because it received no feedback. Add an oil cooler.

Originally Posted by firebird77clone

Ok I'm posting this again, because it received no feedback. Add an oil cooler.

For a street car I don't see that an oil cooler makes any sense. Extra capacity (added cost at every oil change), increased failure points, and little if any benefit. The temperature of the oil, contained in the pan, does little to nothing to affect the coolant temperature which is much more dynamic. External oil coolers are for track cars that operate at sustained high RPM's, and perhaps for tow vehicles pushing the limits on tow capacity. Other than that they are a liability.
Concentrate on getting the coolant flow right and controlling the air flow through the radiator and you'll solve your problem.

thanks for the feedback on the oil cooler.

I'm not sure we see eye - to-eye on this, let me throw my perspective your way, let me know if it makes sense.

Sometimes a cooling system is simply not sufficient. Whether this is insufficient air flow, radiator surface, flow rate or combination is a different discussion. Not enough heat is being removed.

Consider for a moment that the oil is just as capable of moving heat as the water.

SO, if the cooling system isn't removing enough heat, then provide a second path.

By cooling the oil, you are removing additional heat. It's not about reducing the temperature of the oil pan.

It's like turning the heater on full, you increase the cooling capacity by whatever the heater core will move. (You'll sweat, but the engine will drop a few degrees). Only in this case, the additional heat isn't blowing into the cab.

And, cooling the oil has a distinct benefit to the viscosity.

Anyway, beyond an additional failure point, did I change your perspective?

Thanks for your input.

I doubt you'll change anyone's mind and for a variety of reasons. Actually I think you are both right. If the cooling system is configured correctly - adding an oil cooler becomes redundant, and adding an oil cooler as a band-aid will present other headaches such as squeezing more components in an already tight engine bay.. where will you place this cooler? In front of the radiator?? That doesn't seem logical does it? Again, I don't think you're wrong but maybe they go through all that work and expense and still overheat in traffic or sitting downtown... You're still faced with the cooling system isn't correct. And from my memory, the whole number of rows was maxed at 4 and proved to be awful.. to many rows prevented the air from flowing. So then it was the tube size. There needed to be enough flow of coolant being exposed to the tube surface to get max cooling. For quite a long time the honeycomb type was head and shoulders above... except for so many points of failure! LOL.

Originally Posted by firebird77clone

Anyway, beyond an additional failure point, did I change your perspective?

Nope. Fix the coolant problem.

Thx guys. Good discussion.