Piston coatings

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07-31-2009, 09:01 PM
bobqzzi

Piston coatings

Hello- I just wanted to check something here:

The rules say:

"The application and/or use of any painting, coating, plating, or impregnating substance (i.e. anti-friction, thermal barrier, oil shedding coatings, chrome, anodizing, etc.) to any internal engine surface, including intake manifold internal surface, is prohibited."

Fair enough, but I am assuming that OEM pistons that come with a skirt coating are allowed.

If so, if you are making replacement pistons, can they have an equivalent skirt coating? I'm thinking no, but has this been discussed?
08-01-2009, 09:44 AM
joeg

Don't believe its been discussed.

Would have to be a fairly new car with OEM coated pistons. Care to share the make?

I suppose you may not be able to coat equivalent repalcements only because the OEM is likely not specing out the coating publically--so what would you be putting on??

Cheers.
08-01-2009, 01:38 PM
Z3_GoCar

I think I've brought this up in another thread, so it'd be hard to find. I think it was Jeff Young who expressed the opinion that if the OEM pistons were coated, then the only equvalient pistons would also be coated.... My OE pistons were coated, and I'm running non-coated CP forged pistons....
08-01-2009, 07:01 PM
Streetwise guy

Its actually easy to find a coated direct replacement piston. Every Sealed Power piston I've seen lately, forged or not, has a coating on the skirts, which would eliminate one of the largest aftermarket manufacturers from the game.

That is a fairly limited sample size, though. The pistons I see, strangley enough, are for engines that have trouble with piston shrinkage and rattles. The good ones I seldom take apart.:D
08-02-2009, 10:25 AM
tnord

why wouldn't this be like the RR shock issue where you can run the OEM ones, but if you replace them they can't be coated?
08-02-2009, 08:34 PM
bobqzzi

Quote:

Originally Posted by joeg

Don't believe its been discussed.

Would have to be a fairly new car with OEM coated pistons. Care to share the make?

I suppose you may not be able to coat equivalent repalcements only because the OEM is likely not specing out the coating publically--so what would you be putting on??

Cheers.

Newer VWs come with a "grafal" (mahle trade name) coating which is some sort of moly. I was thinking of putting on a similar moly coating. Unless it has been done and found legal, I won't take the chance.