I agree that this aluminium copper rad debate for PC cooling is pretty academic as other factors probably make more difference. An all copper system would probably be the same as the same system but with a aluminium rad, the all copper system might be better as you wouldn't need an antifreeze solution. Yes you could use water wetter but in using it in motorsport applicators I'm not convinced of it's long term corrosion protection.
I work in Motorsport F3000 & Formula Renault sport mainly and in the cold UK the battle, like Michael said is to get the engines to run hot enough. Hotter up to a point is more efficient, on the Renaults we used to tape up the rad ducts to get the temps above 90°C, simply because the extra heat made the gearbox hotter, and so the gearbox oil thinner which = less transmission drag which = a tenth or two.
One of the main reasons motorsort use aluminium rads is nothing to do with specific performance, just they are much lighter than copper and weight saving is a big part of motorsport. A fully copper pair of rads on an F3000 car would be 4 or 5 times as heavy and it matters on a race car weighing around 570 KG all in. Aluminium rads in road cars are now cheaper & easier to make with the modern high quality plastics they use for the end caps. Copper and brass was just the best way back then partly because soldering copper is so easy.
Michael Huck
I've had many fast cars in my wild youth, but a fun one, (because others would try to race you, and loose mostly), was a tatty 75 uk ford Capri with mustang running gear 400+ hp 351 Cleveland. It would run mid 12's on slicks. Current project, (if I ever get it done), is a pro street 70 Superbird with a blown 440
