I’m bringing up the coated pistons thing again..
So it’s my understanding, that in an internal combustion engine, a simple theory was explained to me like this: 33% of the combustion is LOST to heat absorption, 33% is LOST to parasitic/frictional losses (to drive the piston/crank), and 33% is useable power... SO, with that being said, any type of coating that decreases friction, or keeps heat in the combustion chamber, makes the engine more efficient!
Now for a short but significant time of my life, I worked at an engine shop as an engine machinist and builder. We built all sorts of engines, from dragsters, sprint cars, pulling tractors, hot rods, etc... Piston and combustion chamber coatings were just coming of age (back around 2008 or so) and were being used in a lot of high-end racing applications. Coating the combustion chambers, piston tops, and valves keeps the heat from being absorbed into the parent materials, allowing a more complete burn. And anti-friction coatings on the piston skirts is self explanatory, but still useful to reduce extra heat/friction loss. In fact, in V8’s they even started coating the crank and rod bearings with slippery coatings to prevent minute frictional losses.. I guess my point is, although costly, coatings serve to make our engines more efficient by keeping heat where it needs to be to make power, and also to reduce friction.
Lastly, that being said about heat: it is a common misconception in the hot rodder’s world to keep an engine cool - by way of installing colder opening thermostats. While 180 and 165 degree thermo’s have their applications, for most engines this actually reduces power and the efficiency of the burn, by robbing too much heat. Things to think about..