Once knew a harley mechanic who was making his own custom bikes way back in the day. He'd had to fix or trash too many chromed motors due to heat problems. Most of the bikes with chromed blocks were strictly for show and were never meant to be run but the idea, and the bling, picked up and ran away.
They look great but all the heat energy is reflected back into the block instead of radiating away. This is a classic demo of physics in action. Black is the optimal color. The raw aluminum would be next and chrome would be the worst.
