[Henry Schmidt]

There are coatings, TechLine sells them, that actually increase surface area with a the use of a crystalline formation. The theory is that increasing the area that cool air contacts will increase overall cooling. These products were produced to reduce radar signature, drag and heat that formed on the surface areas on the SR71 "Black Bird" spy planes. This coating (offered by TechLine) is black.
The formulas for these products became available through the "freedom of information act".

It seems unnatural to coat something in order too help it cool but it works.
That said, we used it on two race engines and saw no temperature reduction. It is important to state that we really had no way to measure cylinder temperature.