And unlike copper, aluminium corrodes badly inside with age which further stuffs up the heat transfer.
Most Ford taxis here in Sydney fling the crap alloy 2 core rad and fit a copper/brass 3 core. Way better.... I had one in my tow car.

Car makers went to alloy rad cores with plastic tanks for 1 reason only, to save $$$.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I thought that copper rad's are better at getting the heat out of the water, but alu rads are better at radiatiing the heat away? Either way i dont think you would notice the difference between the two if they were both well designed and suited to the car.
Would make sense why a lot of heatsinks have alu fins with a copper slug pressed into the middle.

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Mini - The Wizardry on Wheels!

Copper is just a far better conductor, heat or electricity. End story...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Provided the radiator is capable of cooling the car in all conditions you would be correct, but size for size copper will always transfer more heat than aluminium. Aluminium is used to reduce weight. Copper radiators are heavy and expensive to manufacture.

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Chris

Everything I like is either
illegal, immoral or fattening.