Aluminum vs Copper Radiators, Discuss.

Posted by slowgsr, Feb 20, 2008
Bolt-on Tech - 4G63 intake, exhaust, intake manifold, ignition, fuel system, cooling, etc.

  1. slowgsr

    slowgsr Proven Member

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    Alright.. I need a new rad for my setup, the old ones is rotten.

    So do i go OEM and run a copper core or an aluminum core? What i have always thought is aluminum is better, it cools better etc.

    But what actually cools better, what material can disipate heat better aluminum or copper? I know copper weights more, then aluminum. I think that aluminum rads are used for weight savings only, and copper actually works better then the aluminum just weighs more, but aluminum does the job fine.

    Just a though, any input?
    #1
  2. kahl23

    kahl23 Proven Member

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    A quick google search gave me the numbers that copper has a thermal conductivity of 231*F BTU/hr-ft whereas aluminum has a conductivity of 136*F BTU/hr-ft. Unless I am mistaken, and I very well could be, this would mean that a copper radiator would absorb more heat than a comparable aluminum radiator. Now, the purpose of the radiator is for the heat to be dissipated into the air that flows past it, not into the metal of the radiator. So, the copper core heats up more quickly than an Al core, possibly actually heating the coolant up, depending on how hot the coolant is as it cools (laws of thermodynamics, heat flows from high to low). I'd say if money is no object, go with Al, theres a reason why Fluidyne, Koyo, etc use Al.


    Someone please correct me if I'm wrong, I'm curious here.
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  3. 2gGSX

    2gGSX Proven Member

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    It's all limited by the thermal conductivity of air in the end. The copper radiator would "heat soak" earlier since it is removing the heat faster per unit time compared to the aluminum radiator. Once you add decent fans or start moving the car, then the copper radiator would do a better job at actually transferring the heat to the air (assuming you have enough airflow across the radiator).

    Based on other peoples' research, it seems that radiator design is much more important than radiator material. Their conclusion is that for a performance application, the weight savings of an aluminum radiator would outweigh the slight cooling advantage of a copper radiator.

    U.S. Radiator Testing
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  4. kahl23

    kahl23 Proven Member

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    Cool, thanks for the link :thumb: You learn something new every day. One thing that I didn't see addressed in that test, though I just skimmed it, was the impact of more coolant volume in the radiator from a thicker core, or is this another non-issue?
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  5. 2gGSX

    2gGSX Proven Member

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    They said something about row density somewhere in there, but I'd think that would fall under the "design" advantage.
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  6. kahl23

    kahl23 Proven Member

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    There it is, so, like you said before, its really about design and airflow. I do find it interesting that most DSMers with aluminum radiators (myself included) negate the advantage of the lower weight of their radiator by hanging a frontmount right in front of it...
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  7. dsm-onster

    dsm-onster DSM Wiseman

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    The way I've understood it, aluminum is easier to form and tool. And is much stronger. This means you can fabricate fins with "higher resolution" and much thinner fins with aluminum than you can with copper. This MUCH greater surface area that aluminum affords negates any advantage copper provides though it has a superior heat transfer property.

    An illutrative comparison would be water injection vs. meth injection. Water has a much higher specific latent heat of vaporization than methenol. It soaks up 2.7 times more heat. But if you mist identical amounts of eact, methenol soaks up MUCH more heat. This is because the surface tension of meth is lower. Thus, the droplets are finer. Finer droplets increase the surface area greatly. Just like an aluminum radiator core, the air molecules have more opportunity to colide with a methenol surface to actual do an exchange in energy than it does with a water mist.
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  8. slowgsr

    slowgsr Proven Member

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    well, thanks for the replies!
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  9. Defiant

    Defiant DSM Wiseman

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    Brass/copper radiators are becoming more rare due to the cost of materials. Just call 1-800-RADIATOR and have a new one on your porch in an hour. It'll be aluminum.
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  10. 97GSTAUTO

    97GSTAUTO Proven Member

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    I vote for aluminum. Copper oxidizes and will "rot" Aluminum will not.
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  11. PieEyedPiper

    PieEyedPiper DSM Wiseman

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    Spot on.
    In layman's terms aluminum is also much easier to remove heat from. The copper core would absorb heat more quickly but it would retain it more so than the aluminum.

    If I were to make one, I'd choose to build the core or the heat contact surfaces to be made of copper while I used aluminum fins to dissipate the heat.

    [​IMG]
    Scroll to the bottom for a comment about this practice.
    Zalman's CNPS7700-AlCu cooler - The Tech Report - Page 1
    #11
  12. jumpfroggy

    jumpfroggy Proven Member

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    I'm speaking only from my limited knowledge from college thermodynamics physics class...

    From what I know, copper will transfer heat better than aluminum. As far as I know, if copper "absorbs" heat faster than aluminum, then it'll also dissipate it faster to the air. Plus, if it heats up faster then it'll be hotter, increasing the rate of heat transfer (which is dependent on the temp difference between the radiator and the air... the bigger the difference, the faster the heat transfer).

    But what others said before is basically that the heat transfer properties of copper vs. aluminum don't matter. Copper is pretty soft, I don't think it's as corrosion resistant, and it's heavier and more expensive. Those seem to be the real reasons copper is not used. Combined with the evidence that the heat transfer properties are negligent, it looks DOA for radiator use. Plus, there's always the possibility of the electric properties of multiple metals interacting through the coolant system (some water cooling setups for computers have this problem, not sure if it applies to car coolant systems).

    I'm in the market for a replacement radiator myself. I'm pretty stock right now, don't have any overheating issues. I'm thinking of getting a Mishimoto 2G rad with 2 12" fans, since it looks like a aluminum (ie. slightly better than stock) radiator, not too much more expensive than generic plastic replacements, and would look cool.
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  13. mavisky

    mavisky DSM Wiseman

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    The trick is calculating the volume of water in the radiator (aluminum radiators are typically thicker) along with the surface area of the fins (aluminum will have more fins per square inch typically) and see if the ratios offset copper's heat transfer advantage. If so then aluminum wins.

    I've never seen a copper radiator in a race car, only aluminum though just as a little bullet point there.
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  14. RipperXX

    RipperXX Proven Member

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    mavisky put it pretty much perfectly.


    But you also have to account for any increase in capacity. As more coolant means more weight. Also I have read some where that adding a copper radiator to a coolant system that is going to be flowing though a aluminum head and other parts may be a bad idea for other reasons. Suposedly it can start to store electrical energy in the coolant similar to a capacitor.



    Also since I have never seen a race car using a copper one. There must not be an advantage or they would be doing it.
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  15. slugsgomoo

    slugsgomoo Proven Member

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    I bought a good quality copper core radiator (basically stock replacement) for my galant and it worked fine. However, for the talon I got a good deal on a used fluidyne and I'm totally sold. With less fan, my temps stay lower and the fan runs less.

    I think it's a good mod if you can get one for ~175 used.
    #15
  16. slowgsr

    slowgsr Proven Member

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    I ended up using a new koyo aluminum rad with a 12" and 10" slimfans on the rad, shouldn't have any problems keeping temps down!

    Thanks everyone.
    #16
  17. Mikael SS

    Mikael SS Proven Member

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    who cares? did the stock one not keep your car cool?


    copper is a better material, but aluminum can be better formed to be more efficient. So the simple answer is aluminum ones are better. That's why intercoolers aren't made out of copper.
    #17

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