[sdold]

Why would you want to paint the inside of an engine? What would be the benefit? Possibly smoothing of the airways, but connecting rods and rocker boxes? If it came off it would be a disaster because it would fill up the oil filter.

The color of the paint doesn't matter, white or black or anything else, it all looks black to the infra-red (heat) spectrum unless it's a metallic paint. Bare aluminum reflects heat better than paint.