Why paint the engine?

Many people, especially so called “VW Experts” claim that painting the engine case, cylinders, and anything else is useless, and actually can hurt the engines ability to disperse heat. You can see that Aerovee Engines are “normally” painted in the following manner:

  • Engine Case painted flat black. The case is usually magnesium.
  • Cylinders painted flat black. The cylinders are usually steel (they WILL rust if not painted).
  • The cylinder heads are NOT painted. They are aluminum.
  • The valve covers come with a baked chrome finish. They don’t get that hot anyway, so why paint?

Everyone has heard that a black surface will take on heat faster than a
lighter surface. What everyone does not know is Kirchhoff’s law in heat
transfer, i.e. the emissivity of a body equals its absorptivity. Thus
a black object will give up its heat faster. The problem is that most
paints have a lower thermal conductivity than bare aluminum. So a black
painted surface is better than a silver painted surface but can lose to
bare aluminum. This all changes if you move from ordinary paint to a
purpose designed thermal dispersant which can exceed the thermal
conductivity of bare aluminum. Techline coatings makes them among other
manufacturers.

Comments are closed.