Copper or Aluminum Core Radiators

[IPD]

I'll definitely have to read up on it more...

according to wiki
copper has a conductivity of about 9 watts/inch degree C
Aluminum, about 5 watts/inch degree C

in other words, copper conducts heat almost twice as much as aluminum. However, that doesn't necessarily mean the copper part will work better,


-Aluminum has a low thermal capacity, and a very high thermal conductivity.
-Aluminum just wicks heat away with little concern for anything else. It won't wick as much as copper, but it sure will move it quickly; Dumping it's capacity as soon as any heat leaves the sink, and quickly soaking up more.


-Copper moves heat as well, Copper very efficiently absorbs and transfers heat as does aluminum. It does it faster, as well. That said, copper has an incredibly high thermal capacity.
-Copper won't readily dump all the heat energy it picks up, because it holds so much of it before it changes temperature to any great degree.

so copper needs help. Somehow, you have to remove all that heat from the copper, as it will just hold on to it otherwise. I get that a copper radiator can work better than an aluminum one, but you will have to have loads of tubes,thin tubes, lots of fins, airflow and design... I hear that aluminum is easier to form and tool. And is much stronger, Copper is pretty soft. This means you can fabricate fins with "higher resolution" and much thinner fins with aluminum than you can with copper so the greater surface area that aluminum affords negates any advantage copper provides though it has a superior heat transfer property.

that's another point. PURE copper is more malleable, so it's potentially more prone to fin damage with extended use.

[PaulL]

I'll definitely have to read up on it more...

according to wiki
copper has a conductivity of about 9 watts/inch degree C
Aluminum, about 5 watts/inch degree C

in other words, copper conducts heat almost twice as much as aluminum. However, that doesn't necessarily mean the copper part will work better,


-Aluminum has a low thermal capacity, and a very high thermal conductivity.
-Aluminum just wicks heat away with little concern for anything else. It won't wick as much as copper, but it sure will move it quickly; Dumping it's capacity as soon as any heat leaves the sink, and quickly soaking up more.


-Copper moves heat as well, Copper very efficiently absorbs and transfers heat as does aluminum. It does it faster, as well. That said, copper has an incredibly high thermal capacity.
-Copper won't readily dump all the heat energy it picks up, because it holds so much of it before it changes temperature to any great degree.

so copper needs help. Somehow, you have to remove all that heat from the copper, as it will just hold on to it otherwise. I get that a copper radiator can work better than an aluminum one, but you will have to have loads of tubes,thin tubes, lots of fins, airflow and design...

just like quoted before, aluminum is easier to form and tool. And is much stronger, Copper is pretty soft. This means you can fabricate fins with "higher resolution" and much thinner fins with aluminum than you can with copper so the greater surface area that aluminum affords negates any advantage copper provides though it has a superior heat transfer property.

I will follow up on that with what I just read not too long ago.

The thermal conductivity or heat transfer rate of copper is 92% versus aluminum which is approximately 49%. However, the copper fin bonded to the tubes, or water passages, using lead solder is very inefficient and slows the heat transfer rate to just slightly better than that of aluminum. This can be a disadvantage of copper if the bonding process does not allow the copper fin to touch the brass tube, and why not all copper/brass cores of similar design, but different manufactures, transfer heat equally.
Copper/brass radiators, because of their weight and durability, have been around a long time and can be easily disassembled and reassembled for cleaning purposes. Not the case with aluminum, unless speaking of the O.E. version that comes with crimp mounted plastic tanks. As a result the life expectancy of the aftermarket aluminum radiators will be far less than that of copper/brass.
To better understand the function and performance of any given radiator it helps to understand the “cooling” process and think of it in a way that allows for comparison. The words cooling, or better cooling, or efficient cooling are thrown around a lot in advertising and promotional terms but for the most part un-quantifiable at best without a reference or yardstick to measure by.
To measure and control the cooling processes you have to take several variables into consideration. Variables include engine temperature production at different rpm’s, or engine operating btu output, coolant absorption rates, coolant flow rates, or gpm’s, and coolant temperature reduction rates that will vary with the size of the radiator and the amount of (cfm’s), speed, and temperature of the air flowing through the radiator. The only device to actually compare one radiator vs. another with absolute control is to have a wind-tunnel that can duplicate actual driving conditions under various specified conditions. U.S. Radiator built radiator dyno or test stand in 1999 and tested every core design and manufacturer, in both copper/brass and aluminum, for plain and simple temperature drop, inlet to outlet, at specific and controlled parameters.

So what did U.S. Radiator learn? First and foremost, they discovered that where the radiator is concerned core design and NOT material had the greatest effect on temperature drop. While all radiator cores might look the same they perform differently based on tube spacing and fins per inch. Heat transfer points where temperature is actually allowed to leave the radiator are where the fin is bonded to the tube. The more transfer points, the greater the temperature drop. A 60’s core for example had a 1/2” tube spacing (ie, 1/2” fin between the tubes) and by going from a two row radiator to a four row core design they were able to double the heat transfer points which resulted in a 15-20% increase in temperature drop without changing the other variables (air flow, coolant flow). In the 80's the Japanese came out with a core design in response to the need to down size, which has become the standard, and was efficient enough to allow the re-introduction of aluminum (a less efficient heat transfer material) at the O.E. level. By changing the tube spacing to 3/8", a design referred to as High Efficiency in the industry, more tubes or water passages and fins were allowed across the face of a core with a specific width in inches. The design was simple enough but proved to be very efficient in that more heat transfer points created greater temperature drop inlet to outlet. At this point the move to aluminum construction was purely financial in that raw materials are purchased “by the pound” and a finished aluminum radiator weighs about 25% of a copper/brass unit (dollars per pound being almost equal at that time) and resulted in huge savings to the O.E.’s . This is why we’ve seen most copper/brass manufacturers either switch to aluminum or fold up their tents permanently. It is important to note that this decision was based solely on financial savings and should not be confused with more efficient.

Edit: According to this article, the aluminum radiators wont last nearly as long as the coppers. The copper can possibly provide more reliable cooling over time as well.

[mb7050]

hmm I think i need to find me one of these copper radiators

[PaulL]

Someone posted on one of the other threads that he found out that his 3SX single pass radiator was restricting his coolant flow. He put the stock radiator back in it helped out with his engine temperatures.

[PaulL]

Someone posted on one of the other threads that he found out that his 3SX single pass radiator was restricting his coolant flow. He put the stock radiator back in it helped out with his engine temperatures.

On this topic, now that I think about it, is it unnecessary to have a 2" radiator? If the inlet and outlet of the radiator can only flow so much coolant at a time, then IF the 2" core can outflow these openings, it almost seems to be pointless to have a 2" core unless the inlet and outlet were a larger diameter. I would only assume that mitsubishi engineers would have made size of the openings to be appropriate for 1" OEM core. Anyone ever tested this?

Another thing I noticed as that the stock fan shroud doesn't make a real good seal with the aftermarket radiator as it comes in contact with the slightly elevated sides to allow that much less sucked in through the radiator.

[IPD]

On this topic, now that I think about it, is it unnecessary to have a 2" radiator? If the inlet and outlet of the radiator can only flow so much coolant at a time, then IF the 2" core can outflow these openings, it almost seems to be pointless to have a 2" core unless the inlet and outlet were a larger diameter. I would only assume that mitsubishi engineers would have made size of the openings to be appropriate for 1" OEM core. Anyone ever tested this?

Another thing I noticed as that the stock fan shroud doesn't make a real good seal with the aftermarket radiator as it comes in contact with the slightly elevated sides to allow that much less sucked in through the radiator.

regardless of how much flow a 2" core with stock feeds can flow, if it has more surface area for heat-exchange, the coolant will exit the radiator at a cooler temp--assuming sufficient airflow under identical conditions.

[PaulL]

regardless of how much flow a 2" core with stock feeds can flow, if it has more surface area for heat-exchange, the coolant will exit the radiator at a cooler temp--assuming sufficient airflow under identical conditions.

Well, that leads to the question, can the fans move more air through a 1" core vs. a 2" core due to less resistance?

[BigTyla]

Well, that leads to the question, can the fans move more air through a 1" core vs. a 2" core due to less resistance?

All things being equal, absolutely.

[PaulL]

All things being equal, absolutely.

I know the two radiator designs aren't equal, but its worth trying an OEM radiator to see if it helps the heating up at idle issue. I will have to give that a try when I can free some time and spare money up.