Dave, that's very good thinking. I don't have answers but maybe some ideas will trigger others.

If one is drag racing and it's over in 10 seconds or less, overheating the engine is the last thing to worry about. Keeping the heat in the chamber to do work is the goal. The same goes for dyno numbers. How long does a dyno run last? so if you want max dyno numbers, the coatings are a must.

There was an interesting article in Motor Trend about running the new Corvette on the Nurburgring. After one or two laps the engine temp got warm and the control system started limiting power. Lap times increased noticeably. What good is a high performance car if it only works for 10 minutes and then limits power?

The cats at Chrysler wanted the Hellcat to be able to crank out max power indefinitely and so they paid a lot more attention to getting the heat out, thus the use of a more conductive alloy. I don't think it is a night-and-day difference in thermal conductivity, I am not aware that different aluminum alloys vary that much. But as an engineer, I understand the concept of making choices that increase the value of a product. Why not do it on every Chrysler engine? Because it slightly decreases fuel economy, and every hundredth of a mpg is worth money. The Hellcat is limited production and losing a couple of tenths of a mpg is part of the cost of doing business.

Heat transfer is tricky stuff. Each type of transfer has its own constraints, and some are not very intuitive. For example, the heat that transfers through an item can be limited by the conductivity of the item, but it can also be limited by the heat transfer into the item or out of the item. So one could use pure silver to conduct heat better than about anything else, but getting the heat into the silver might limit the total heat flow so that aluminum would work just as well. That's an oversimplification used for demonstration.

R.