Originally Posted by Sniper
Fins in a radiator are copper, not brass. the tubes are brass.

copper/brass is better at heat transfer than aluminum. Though that level of better is limited by the lead solder connecting the fins to the tubes but even with that limitation it is still better than aluminum and the design of the fin tube interface can ameliorate the silder issue.

https://www.hotrodhotline.com/content/aluminum-vs-copper-brass-article-us-radiator#.XjJI8Yh7mM8


as per link:

"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."

Doesn't address directly the issue of the lower conductivity of the brass tubes vs/alum.

Explain the method of ameliorating the copper/brass interface to any significant degree in this situation.

I'm also wondering, what exactly does "92%" and "49%" referenced to, pure water?

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.