Aluminium is easier in manufacturing and is lighter than copper/brass radiators. Copper is much more expensive, heavier, required a combination of welding and brazing to patch up the inevitable quality differences. Classic car restorers have to scrounge early 70's cars for copper radiators to use for parts to restore their classic radiators. The design of the alumnium radiator is higher flow, so the heat transfer ability of the metal is less important. Over the years I have replaced 3 copper radiators with same sized aluminium and they weren't as efficient for those cars.
The problem with that was the lines I used were too small. Pressure at idle was ok, but as soon as the revs (and oil flow) increased the pressure dropped right off. If I used -16AN lines it would have been fine.
thats really interesting and more so seeing as it seems to confirm my personal beliefs. interesting though because the last radiator guys I spoke to insisted that a copper radiator was less efficient than an ali one (of the same dimensions) and that I should dump my copper cored Z radiator for an ali one.
Copper has a much higher thermal conductivity than Aluminium. http://www.extron.com/technology/img/thermalmgt1_ts_2-lg.jpg For the same reason higher quality computer systems have Copper heatsinks whereas cheaper systems will have Aluminium. Particularly at higher temperatures. AFAIK Copper will maintain a much higher thermal conductivity than Aluminium at higher temperatures. However I would also take into consideration the type of core used. Ie would a radiator of higher flow, in one material, dissipate more or less heat than another with less flow, in the other material. However in terms of longevity, I would expect the Aluminium to last longer. Mainly in terms of corrosion of the thinner material used in the actual radiator core.
