Quote Originally Posted by Cathar View Post
...It is (of course) impossible for the air-temperature to ever be more than the water-inlet temperature though. So the proof that they are defying the laws of physics still holds true based upon the analysis in this post...
Two factors that may or may not be worth considering are compression and friction.

Air will get slightly compressed entering the radiator, then heated to up a maximum of the water inlet temperature, then decompress on exit thus lowering exhaust temperature.

Dunno if there is any noteworthy friction coefficient at these airspeeds, if there is it could heat the exhaust past water inlet temp.