Sammy, re your specific questions and thoughts
(I understand that the coating increases thermal efficiency, but by how much I plan to have my piston crowns and the chamber area of the head coated. My understanding is that the insulating properties of the ceramic will reflect the heat energy back into the fire, letting it extract more energy out of the fuel?)
I don't have quanitative figurers, and I suspect that 100 tests would give 100 different results, but I do know that the ceramic coatings must go on very thin so as to avoid flakeing off. This means that even though they might be very good insulators, they are only effective for a very short time, so they in efect delay the heat transfer dureing combustion, until the next fuel charge comes in and cools everything.
(HC emissions should be lower because you reduce the rapid cooling that affect parts of the mixture in contact with the chamber walls.)
I don't think you are right on this one, as even though the re is less heat lost from the combustion chamber, that which is lost is concentrated at the surface in the ceramic coating.
(Exhaust gasses should be hotter and therefore lighter)
Once again, not strictly true. If you heat a gas in an unrestricted environment, it expands and reduces density, but if you heat it in a closed environment, it cannot change volume, therefore cannot cannot change density, but it does increase in pressure. A combustion chamber is an alternating, closed, limited variable and opened by a very restrictive path environment, so it is realy quite a complex dynamic situation, but basically, the extra power comes from building higher pressurs in the chamber and higher pressure difference accross the turbo, thereby increasing gas flow and increasing turbo spool up speed
(plan to coat the header, turbo housing and downpipe).
I agree with coating the header and turbo, but the downpipe is probably not really worth it, except for cosmetics.
(Under hood temps and general operating temperature should be lower because less heat energy will be absorbed by the engine and exhaust parts.)
Wrong. The heat is not absorbed, but actually left in the combustion/exhaust gas, which allows it to be carried out the exhaust pipe, rather than released into the water, oil and air around the engine.
(This should increase oil life and give the ability to run thinner oil.)
Yes and no
If you reduce oil temperaturs enough, so as to need a change to it's viscosity rateing, so as to maintain the optimum viscosity, you end up back at the optimum viscosity, which is where you started, no net gain, except dureing warm up. Re oil life. the main limiting factor determining oil life of any good synthetic oil, is Total Base Number, not resistance to oxidation, so the oil change interval is not really changed. The main advantage of a good synthetic here is that being more resistant to oxidation, they do not carbonise as much in the area of the turbo bearing, so a cooler turbo will be less prone to the oil lines and galleries in the turbo becomeing blocked with chared oil breakdown deposites.
(What about ceramic as an aid to reduce friction? Some piston manufacturers offer ceramic-coated skirts. How does this help?)
See techline coatings site for this info
(Could the same principle be applied to maybe valve stems to reduce valve train friction?)
The gains are small, especially relative to costs, that is why most serious race cars use a variety of ceramic coatings, but auto manufacturers rarely use them.
One extra advantage of coating the turbo houseing is that it helps reduce cracks in the wastegate seat area (as does polishing and removal of stress risers). Cracks at the wastegate seat, caused leaks, severly damage boost build up, thus so greatly increasing lag times.
Regards
pat