Ceramic coated pistons

[88v8]

New one on me.
Mentioned here (in a Stag V8)
http://www.ebay.com/itm/331641303051?forcerRptr=true&item=331641303051&viewitem=

I find plenty of references on the web, going back some years.
Merit? Or smakeoil?

Ivor

[MG four six eight]

Coatings on piston skirts are common on latter OEM engines. Almost all of the newer GM engines I have taken apart have some type of coating on them and it wears surprising well. Even with over 100K miles on them the coating is still intact!

I would say it's legit as manufactures would not go to the added expense to have them coated if it wasn't effective.

BTW, that looks like a good build on that Stag engine.

[Nexxussian]

Various coatings have excellent merit on pistons, as well as other components, especially since several of the OEs today are using piston skirt coatings for friction reduction and gall prevention.

I seem to recall some are even anodizing the crown and top ring land.

However, the ebay listing mentions "ceramic" coating and says it's for both heat and friction reduction.

In the applications I've seen, a different coating was used for thermal barrier (crown) and friction reduction (skirt), with the possibility of a third type for the underside if oil shedding or better thermal transfer was desired (much discussed, but I hve yet to see that one used).

Much like any other coating, the quality of the product and the care in its' application will determine if it performs and lasts as intended.

Then comes the other caveat, it's ebay, are they actually coated?

Before I would buy such an engine, the current owner would have to convince me it not only had what they claimed, but it was something I wanted, which would include telling me what actual coting it is, and who applied it.

Not much is more disapointing than loosing an engine because the oil pickup is packed full of something hat was supposed to be beneficial.

[BlownMGB-V8]

It's an added expense. The main question is how long will it last before either wearing through or coming loose. That will depend on the quality of the application. I was one of the first to try ceramic exhaust coatings by a most reputable coater at considerable expense and it was nowhere near as good as the generic coating you get today by anybody. Began to fail immediately on exposure to road salt.

So it's generally a slope. First adopters get to pay to experience early failure as the product gradually gets better. Can't really say where on the slope we are.

Jim

[britcars]

I've used ceramic and dry film lubricant (DFL) coating a number of times, ceramic on headers, combustion chambers and piston tops and DFL coatings on piston skirts, cam bearings, lifters, etc.  Sprayed and cured in an oven and the ceramic coating polished with glass beads.  A set of headers on my Rover v8 is holding up well after 7 years of use.

http://www.techlinecoatings.com/hi-performance/bs-internal-engine-coatings.html

[88v8]

So how do you allow, dimensionally, for skirt coatings?

Ivor

[quietone]

The pistons that come coated say do not consider coating film in clearance. Some of the new hi-tech engines from GM have a clearance spec of 0.000 to -.014. I read somewhere the new allowed oil consumption is 1 qt./ 7000 mi.