[joshbarnett]

I am in the process of replacing a 34 inch 4-row copper rad with an aluminum one. Based on my research, all else held constant, aluminum rads are more efficient at cooling. Does that mean that a 3-row aluminum rad can cool as well as a 4 row copper rad? Anybody care to you share your experience?

 

[BogiesAnnex1]

I’ve run both on the street, rather than the lab, there was no difference in performance between a 2 row aluminum and a 3 row copper brass with the same face area and fin count.
Bogie

 

['48 Austin]

Nearly all racing classes with radiators run aluminum for light weight and efficiency. Nearly all auto manufacturers use aluminum for light weight, cost, and efficiency. All of my vehicles (Custom and Production) have aluminum for light weight, cost, and efficiency. In my mind use an aluminum radiator that is oversize as far as cooling capacity especially if running AC. Since the aluminum is lighter, you can use a higher capacity aluminum radiator and still end up lighter than a copper radiator. Full shroud, good cooling fan, and no gaps over top and sides of the radiator forcing all air coming through grill to go through the radiator instead of around it, are all essential for good highway and stop and go traffic cooling. The numbers are obvious when comparing price of a Walker Copper Radiator to a Champion or Northern Aluminum Radiator.

Which is The Best for You? Aluminum or Copper?
1. The price distinction between copper and aluminum radiators
At the moment, the market price of copper materials far outweighs the price of aluminum materials. Copper materials are several times more expensive than aluminum materials in terms of cost alone. As a result, in order to save money, many automotive radiator manufacturers and buyers will prefer aluminum car radiators.
2. The difference in welding between copper and aluminum car radiators
Soldering is used to join the copper car radiator for sale. The welding medium is tin, which is achieved by melting and cooling tin, whereas the welding of aluminum car radiators is brazing of aluminum, which uses the different melting points of different aluminum alloys, as well as melting and cooling of the aluminum alloy itself in a specific atmosphere. The aluminum car radiator has no excess components doping, ensuring consistent performance from start to finish.
3. The difference in heat dissipation capacity between copper and aluminum automobile radiators
Copper materials have a relatively high heat dissipation coefficient. Copper products therefore have a higher heat dissipation capacity than aluminum products. However, because welding of copper materials is dependent on the melting and cooling of tin, there is a layer of tin-lead alloy hanging on the surface of the copper car radiator's heat tubes and the cooling fins. Although copper has a higher heat dissipation coefficient than aluminum, there is a layer of tin-lead alloy between the heat dissipation components, resulting in a much lower overall heat dissipation coefficient for copper car radiators.

Also, check out article below for more good information:

Bulletproof cooling system

www.crankshaftcoalition.com

 

[75gmck25]

Also, don’t let anyone confuse you by comparing the quality of old-school copper to an aluminum radiator with plastics tanks (apparently common for oem). Quality all-aluminum radiators are readily available from many suppliers.

When I was shopping for an aluminum radiator several years ago, the the Champion radiators from Jegs seemed to have a much more reasonable price point than other aluminum radiators. They also cross-referenced to stock radiator numbers and sizes so I just looked for a CU161 size. I’m not sure how they compare today.

 

[johnsongrass1]

I've been buying Eagle radiators from Amazon for around 10 years now and they have been super.

 

[2old2fast]

Aluminum core with plastic tanks last just fine for me , got 21 years & 220 k miles from my truck before a tank cracked .
Copper brass in my 84 GMC has 225k miles & hasn't been out of the truck .
Welded aluminum in my T has 50k miles @ 22 years without problems .
All three do their job .

 

[curtis73]

Here is the sciencey part.

Both copper and brass have a higher specific heat capacity and better conductance than aluminum, so the physical ability to conduct heat is higher with copper/brass. The caveat, however is that copper and brass are both more malleable and can't take pressure as well as aluminum, therefore they have to be constructed with round tubes. Aluminum radiators can be constructed with flat tubes that drastically increase the surface area-to-volume ratio, which more than compensates for it's lower conductance.

A same-size aluminum radiator will almost always shed more heat per square inch than a copper/brass radiator. It will also be lighter and not as susceptible to corrosion. Nothing wrong with copper/brass, but aluminum wins in nearly every category for radiators.

 

[joshbarnett]

Here is the sciencey part.

Both copper and brass have a higher specific heat capacity and better conductance than aluminum, so the physical ability to conduct heat is higher with copper/brass. The caveat, however is that copper and brass are both more malleable and can't take pressure as well as aluminum, therefore they have to be constructed with round tubes. Aluminum radiators can be constructed with flat tubes that drastically increase the surface area-to-volume ratio, which more than compensates for it's lower conductance.

A same-size aluminum radiator will almost always shed more heat per square inch than a copper/brass radiator. It will also be lighter and not as susceptible to corrosion. Nothing wrong with copper/brass, but aluminum wins in nearly every category for radiators.

Interesting point. So I guess the answer to the question of "Does that mean that a 3-row aluminum rad can cool as well as a 4 row copper rad?" is "maybe", because it's hard to quantify the benefit above and beyond simply that aluminum cools better.

 

[curtis73]

As to your initial question, Yes, a 3-row aluminum will almost definitely cool better than a 4-row copper. This is partly because a 3-row aluminum will have significantly more surface area on the tubes, but also because each successive row added to a core drops efficiency a bunch because it's getting hot air from the row in front of it.

 

[Racer-X-]

all else held constant,

In the real world, that's never the case.

aluminum rads are more efficient at cooling. Does that mean that a 3-row aluminum rad can cool as well as a 4 row copper rad? Anybody care to you share your experience?

Copper and brass are better for heat transfer. And tin/lead solder isn't as bad as one post above seems to make it sound. However, copper and brass are not as strong as the aluminum alloys used for radiators. As a result, the material in copper/brass radiators is usually thicker than the same materials in an aluminum radiator. Copper/brass radiators nearly always have significantly fewer fins per inch than aluminum. And as has been pointed out, round tubing is used in copper/brass radiators, where aluminum radiators use oval or rectangular section tubing.

Just as a general rule, one row of oval aluminum tubing with the typical fin count found in most "all aluminum" radiators has about the same cooling capacity as 2 rows of copper tubing with copper or brass fins.

I'll also agree with something mentioned above and restate this a little differently.

Installation, fan(s) and shrouding, and ducting or aero deflectors make a huge difference in the total cooling capacity of a radiator. If the installation is properly sealed and ducted so that absolutely all the air coming in the grill opening goes through the radiator, and the fan is efficient and adequate and is shrouded so that all the air coming through the radiator must pass through the fan(s), the system will be much more efficient at cooling the engine than if the radiator has open space around the edges or the fan is unshrouded. For the fan shroud, another alternative is "flaps" that open for greater air flow at higher speeds, those flaps are closed and relatively sealed when the vehicle is stopped, so the fans don't draw air in through the flaps, but rather draw all of their air flow through the radiator core.

 

[cerial]

The biggest diffrence is in the sides. Most oem use plastic sides for aluminum while with brass they (often) have no plastic.

Plastic sides can and do crack over time. The plastic also insulates vs sheding heat like metal sides can.




Here is my best recent comparison.


This 91 geo had a brass radiatior factory with the stock fan.

I replaced it with a slightly taller and larger capacity aftermarket radiatior using a new stock fan.

The aluminum radiatior is noticably lighter. I want to say 2 to 3 pounds.

It holds .6 more quarts. Which does not sound like much until you consider the normal capacity is 4.1 quarts(yes tiny engine). So for about the same weight(of the added fluid) around a pound lighter overall. I have a 4.7 quart system. That is a 14.6% increase just from running aluminum.


The cost of a fully aluminum radiatiors have come down significantly. Actually on a few silveradios I have found direct bolt in full aluminum for less then the cost of a oem replacment with plastic sides.

Full aluminum is often less cost then full brass and the chance of you finding an aluminum replacment in 5 years is much higher then finding the same brass replacment for a similar price point.

 

[Eduramac]

The biggest diffrence is in the sides. Most oem use plastic sides for aluminum while with brass they (often) have no plastic.

Plastic sides can and do crack over time. The plastic also insulates vs sheding heat like metal sides can.




Here is my best recent comparison.


This 91 geo had a brass radiatior factory with the stock fan.
View attachment 629238

I replaced it with a slightly taller and larger capacity aftermarket radiatior using a new stock fan.
View attachment 629239

The aluminum radiatior is noticably lighter. I want to say 2 to 3 pounds.

It holds .6 more quarts. Which does not sound like much until you consider the normal capacity is 4.1 quarts(yes tiny engine). So for about the same weight(of the added fluid) around a pound lighter overall. I have a 4.7 quart system. That is a 14.6% increase just from running aluminum.


The cost of a fully aluminum radiatiors have come down significantly. Actually on a few silveradios I have found direct bolt in full aluminum for less then the cost of a oem replacment with plastic sides.

Full aluminum is often less cost then full brass and the chance of you finding an aluminum replacment in 5 years is much higher then finding the same brass replacment for a similar price point.

When you are comparing the two for cooling effects you must consider the fan setup. Many times you see a copper brass rad replaced with a alum unit with a less than efficient fan set up. Fans stuck to the rad with no shroud. Where the copper brass had a fan driven blade with a proper shroud. So in order to compare the two they both need equally placed fans and shrouds.

 

[joshbarnett]

So in order to compare the two they both need equally placed fans and shrouds.

That's fair and I do realize that. That's why I pointed out that "all else held constant, aluminum rads are more efficient at cooling...".

 

[cerial]

If the radiatior thickness is different from brass to aluminum then a spacer(s) can be used to maintain the shroud geometry.

Much easier way is to move the radiatior closer to the engine then use a spacer between the core support and radiatior then putting the spacer between the radiatior and shroud.

If the shroud needs to be shorter then the face(that meets the radiatior) can be cut back and a new face fabricated.

Much easier way is to move the radiatior away from the engine. It may require core support modification. If the core cant be or you simply dont want to take lets say 1/2" off the core then cutting the shroud is the alternative.

Another alternative is a shorter waterpump. But most engines do not offer a shorter pump.



The clutch fan to shroud should be able to be maintained. Despite radiatior thickness. In most cases your talking about 1/2" of modification if your fitting a larger radiatior then some modification should be expected.

Unless your switching from a engine driven fan to a electric of course.

Going from a "bolt in" brass to "bolt in" aluminum there should be little modification.

Take lots of measurments like fan blade depth inside shroud before removing things so you can maintain that. Also make sure you take and mark the center of the shroud to core support refrence. In some cases the "bolt in" radiatior will move the shroud horizontally. Not much. But enough where that fan is not centered and contact may happen when things flex/twist.

 

[joshbarnett]

Thanks for the input guys. Just to sum this up, last night I swapped my copper rad with an aluminum one. Again, the only difference was the new rad has 3 rows instead of the old 4, so the new rad is thinner, but otherwise the dimensions are pretty much identical. I put the shroud back in place and made sure there are no gaps by pushing the (thinner) rad forward using some spacers. Drove it today for about 30 minutes. And... there is no noticeable difference in operating temp from the old one - the temp gauge stays consistently between 170 and 180, just like before.

 

[2old2fast]

What was the ambient air temp during your test ?

 

[joshbarnett]

What was the ambient air temp during your test ?

About 70 degrees.

 

[johnsongrass1]

Thanks for the input guys. Just to sum this up, last night I swapped my copper rad with an aluminum one. Again, the only difference was the new rad has 3 rows instead of the old 4, so the new rad is thinner, but otherwise the dimensions are pretty much identical. I put the shroud back in place and made sure there are no gaps by pushing the (thinner) rad forward using some spacers. Drove it today for about 30 minutes. And... there is no noticeable difference in operating temp from the old one - the temp gauge stays consistently between 170 and 180, just like before.

To me that means the systems is over built for it's capacity and simply didn't care. That sounds like the thermostat is the regulator of the temps.

 

[MikeTudor]

Aluminum core plastic tanks are in the top 5 for cooling and weight

 

[MikeTudor]

To me that means the systems is over built for it's capacity and simply didn't care. That sounds like the thermostat is the regulator of the temps.

Along with the fan/s.