[Bicycle Bob]

Moving a standard rad to another location is not usually recommended, because it needs air flowing through it. A surface radiator, with air just flowing over it, has to duplicate the surface area of the regular one, which is considerable. If you are able to have true laminar flow over it, you need far more area. However, the usual case is a turbulent, but attached boundary layer. So, how to produce a large, contoured heat exchanger, able to contain pressurized fluid? The tube and panel solar collectors are a good model. It should be possible to make a composite panel using aluminized fiberglass (40% by weight) to improve heat conduction, and mold in coolant ducts that double as panel stiffeners. Vulnerability to damage is certainly an issue, as is weight, however, the potential savings are about 20% of the total drag. Perhaps a combined radiator/belly pan would make a good add-on, for more combined savings.