Considering ALL the factors of copper v alum for radiators, alum wins out. As long as it is welded/brazed not epoxied.
- while copper is a better heat conductor, larger tubes can be used in alum radiators which allow for more efficient fin design, the fins being what actually sheds the heat.
- the brass & solder used in copper rads are poor conductors of heat.
- the alum rad is more robust, especially in vehicles where it is NOT rubber mounted. The soft solder can crack/leak in copper rads from road shock/big pothole.