Another overheating situation 63 Slant six

Further to post #39: Copper v alum
"Copper is fairly weak, so to avoid coolant tubes exploding due to water pressure, the tubes must be kept quite narrow. Alum on the other hand is much stronger so the tubes can be twice as wide. The flow characteristics of a four row copper radiator are pretty much the same as two row alum core. However, when we consider the heat transfer area, the alum tubes easily win o the tune of up to 20% gain. The fins, which transfer het to the air passing through the core, only contact the flat sides of the tubes. The rounded ends of the tubes have no finning, so there is no heat transfer of any significance from this area. Thus with only twice the number of tube ends, the alum core will give up more heat to the fins.