Coated Piston skirts and engine bearings, Yes or no?

[Youngblood]

Anybody have some good or bad opinions?

I'm getting ready to rebuild a roller cam Chevy 350 and I'm looking into coated bearings (a hot street motor). From what I can tell some of the coatings are PTFE based and I don't really want that (remember Slick50). Maybe for the bearings but not the piston skirts? I don't really like PTFE in the cylinders but the bearings probably would be ok or am I just wasting money.

Matt

 

[kschachn]

Coated pistons and bearings are typical and are nothing like snake oils that tried adding PTFE powder to motor oil in direct opposition to what DuPont recommended.

 

[AJB0009]

I have no idea, so I'm just asking a question that came to my mind:
What is the cost?
What is the actual, real world benefit; if any?
If there is an actual, real world benefit; is it worth the cost?
Increased HP? Torque? Longevity?

 

[bullwinkle]

Seems like coated bearings would be better in race applications, where engines are rebuilt often. As opposed to conventional applications, where a longer lasting surface would be desired. I would think that wearing off the coating might make oil clearances too large? With a resulting loss of oil pressure?

 

[bdcardinal]

Yes absolutely. The Mahle pistons with Grafal coated skirts are used often in racing engines. Also the Clevite coated bearings are pretty common also.

If you want to get real cool, have the wrist pins DLC coated along with the valve stems and lifter bodies.

 

[930.engineering]

Coated pistons are pretty common today. I've seen them pulled after 100,000 km
and they coating still looked like new. I'd love to be real cool and have as many
parts DLC coated as possible if I ever have an engine revision.

 

[nthach]

The OEMs have been using moly-Teflon coatings on pistons for years now. Nissan and Ford are using plasma-arc spray for their bores instead of Nikasil/Alusil or pressing in steel liners.

If anything, better durability and better tolerance to oil starvation.

 

[K.Aoi]

The OEMs have been using moly-Teflon coatings on pistons for years now. Nissan and Ford are using plasma-arc spray for their bores instead of Nikasil/Alusil or pressing in steel liners.

If anything, better durability and better tolerance to oil starvation.

VW too now on the plasma spray bore on the new 1.5T as well. But yeah coated pistons are the norm Joey, every manufacturer uses them for good reason.

 

[Youngblood]

Thank you for all the replies.