Well today I finally got to speak with someone whom could actually answer my questions!
I talked with a Head Tech at Swain coatings (only after telling 2 preceding ppl my questions and lsr plans). As well as a tech at Intellectual Alliance.
To paraphrase, in particular order:
ptfe (teflon based) products. Here he had very strong cautionary words. Essentially ptfe (teflon is a dupont name but...its the same stuff) is oil phobic, so oil wont stick to it. Not good for a skirt coating, obviously. {{Now he didnt say this but these are my thoughts on the subject of teflon - teflon is a paint product. It can be applied via spray or silk screen. Caution should be used in using it (paint) in side the engine close to the piston, as high heat can degrade the paint to point of uselessness. }}
molybdenum disulfide skirt coatings - Much better for skirt coatings. Even though moly is not hard it is tough and has very good lubricity. {{ I havent talked with or discovered how it can be applied, but my cautions for paint remain. Heat degrades them. I will continue my search for application methods. If plasma is available I would think it is the better method.}}
skirt coatings- general comments from the tech at Swain. frequently not alot of measurable benefit is achieved. If proper tolerances are created and lubrication are present, it shouldnt (friction) be a big issue. WHAT skirt coatings do, do is to create a barrier when the aforementioned tolerances and lubrication are absent. In addition he said that only in very highly stressed applications are benefits observed and needed.
dlc coatings or Diamond like carbon - *here I want to paraphrase both the conversation with swain tech, and a conversation with Intellectual Alliance in Vaughan Ontario* (Intellectual Alliance provided me with some links to a scientific journal from 2006 that talked about measurable results - New Diamond and Frontier Carbon Technology Volume 16, Number 4 -2006 ).
ok, DLC coatings are very hard and require special surface prep. nearly mirror smooth surfaces or else when the DLC is grown (its a crystalline structure) it will wear what ever it mates to like sandpaper, only harder. Period. That makes surface prep $$$. I had linked to beakert.com previously and they shown pistons (highly unlikely outside of designed specs due to their required prep) but valves are possible, but if the valves require something with a "super low coeffiecent of friction", (then there is likely a design issue with normal lubrication) , but I didnt realize that the pics in Beakert too should have been regarded as marketing (ooooh look at the farkle..). In the tech article I mention above, they do talk about upto a 40% gain/savings in torque in the valve train when dlc is applied to the shim/bucket. That being said I dont recall what the input torque was (<4kg/m?). But if the potential input is large, like from a large V8 with cam driven gears the savings may not add up to much at all. It must be noted that their best results were achieved using an ester based oil.
It was suggested that dlc be applied to the rings, as they are the biggest contact point (for friction) in the piston assembly. Interesting thought.
lastly ceramic coatings - now this is more application specific. Keep in mind that my project is intended for the Mojave mile not a long track or short track salt racing, nor is it going to be running on race fuels, just pump gas. So with that being said a ceramic coating on the top or bottom likely wouldnt be of much use. The ceramic helps prevent heat build up and with run durations of (possibly) under 3 min, I would not see any net benefit. For guys running longer with lots of power (ie heat potential) then it maybe of benefit. Or track racing where it is constantly being run at wide open throttle. Then maybe, but not me.
Read the article it really is quite intriguing. If you want a copy and cant figure out how to find it, then pm me.
Cheers
Alan