Ducman82

i was thinking about getting my pistons / lifters coated. i have read a few posts on here about DLC and some others. any one have any experiences with that?

thanks a bunch!

BC

Pistons coated by swain tech. Haven't run the engine... (yeah, engine was built in 2007, pistons were coated in say, 2004)

GregB uses a form of the DLC on lifters. It reduces stress on the valve train.

The pistons you took from the 5L need to be coated because it looks like the tin/iron coating on the pistons has been worn off.

Ducman82

thats what i figured. when i get them back form getting the machine work done ill get that coating done. im just not sure on what is available.

Ducman82

i called the local hot rod guys, they sent me to this site.

http://www.polydyn.com/coated_pistons.htm

seems like a good idea.

BC

Make sure you check out swaintech.

Ducman82

o i will. email send to you as well .

RKD in OKC

When I had my 944 Turbo rebuilt, Swain was considered best for internals.

tmpusfugit

I have an engine (not a 928) that was treated to Polydyne coatings on all the bearings, ceramic coated piston tops, ceramic coated combustion chambers and exhaust ports, graphite coated piston skirts, oil shed coatings on all the rods and counterweights of the crank and undersides of the pistons....also had all the rotating parts cryogenicly treated, along with valves and valve springs. Cam was also Polydyned.....how does it work? Quite well so far...unfortunately I don't have anything to compare it to directly....would I recommend it for a build? For the street, maybe not, but for serious racing or other performance related driving...yes I would. It was not as expensive as I originally expected, but it was not cheap. I knew I would be pushing the engine and I wanted it to last a bit, so maybe I went overboard, but it sure is fun....

namasgt

I think the coating for the lifters (dimond coating?) is very expensive, last time I talked to someone about it, they were quated more than 1000 dollar just for the coating and the lifters had to be brand new. I would not consider coating the pistons, If your piston skirts are not damaged and the cylinder walls look good why risk it. Some have attempted the coating on the piston skirts and the engines have failed after a few hundred miles.

slate blue

The big step forward that started about 5 years ago in F1 is dlc coated pistons which would work well with our alusil. A "substantial" reduction in friction and increase longevity in race engines. It was one factor in the increased engine life of F1 engines. Normal pistons coated with dlc do not show a reduction in friction, they need to be specially made and have highly polished skirts before application. They are expensive but the cost is coming down.

BC

Any links to that technical info?

Rob Edwards

As a data point, I bought a new set of lightweight lifters for $720, paid $240 to have them clean enough for the DLC process, and $1280 to get them DLC'ed. A few out of the set were not 'good' enough to be DLC-able.

No idea what the hp/dollar cost was, but whatever it is, there's probably cheaper hp to be had elsewhere.

Ducman82

from what i have gathered, the 16v lifters are just to complicated to take apart for the DLC coating to work right. i can think of better things to do with that kind of money for the car. now the pistons have me thinking. i know a few buddies in the muscle car biz ( i got out of that years ago) that now coat the skirts and domes of the pistons, and seem to really like the out come. my bores are in great shape, no wear. the side of the pistons look fine as well, some light spots but no major damage in my book. if i could get them re factory coated that would be kinda cool. but i dont see any info on getting that done.

slate blue

Brendan that info was a pay for information basis, occasionally they (Race Engine Technology) release free info as bit of a bait. Also I did speak to the coater in the UK, have details somewhere, and his opinion was it would work in our engines on the basis that it does work in the piston pins of all types of pistons, i.e high silicone and low silicone and MMC. No guarantees though.

Rob Edwards

FWIW, here are the skirts from the GT pistons I pulled from the stroker donor motor and had Greg clean. He said their coatings were were fine to use as is, in a stock block, they were a set of tolerance group 2's that I sold to Abby.





These sat in the Berryman's on their side and left an impression on the skirt, still not a problem: