Piston top and skirt coating

I am rebuilding my M96 and need advice on the value/wisdom of getting a ceramic coating on the top of the pistons and a different coating on the skirt.The better M96 rebuilders seem to use coatings Swain seem to be often mentioned for other engines and their prices seem reasonable : http://swaintech.com/race-coatings/a...s-price-sheet/ Does anyone have experience to share on which specific coating to choose and who to apply it? I do not plan to track the car but do drive it hard sometimes and plan to keep it for many years (assuming the rebuild goes well!) Thanks for any advice and I hope this thread will be of interest to others rebuilding the M96.

SpeedrII fixed a rod bearing and along the way had his pistons coated .I think a search on his handle will provide more info .

I had a maniold on an older Nissan Slalom car done by swain..still seems OK after about 3 years..also drive it on the street some..A local engine builder uses Swain for ceramic/heat coatings for nitrous cars and some that are blown...Seems OK by him too. Central CT coatings is about the best around here. Does ceramic coatings on pistons and crowns and inside and outside of headers and manifolds. I use him a lot..52 village ST E. Hartford CT. [phone removed]. Does great work..will do you chassis too if you want it done. Been in business for over 30 years. Mixes his own powders great guy to work with named Gene Schaeffer..good prices too. Check it out...Rich

Thanks for that, yes the Flying Finn did get his coated -but in Finland with a local treatment. There seem to be several rival treatments in the U.S.A. and I am curious about which is the best to use. The older/cheap ceramic coatings for the piston crowns can crack/flake which would be a disaster.The cheap skirt coatings are sometimes considered 'break-in' only treatments and wear off within a 1000 miles.They are extensively scuffed within a few hundred miles. I can't find any reliable reviews .There are plenty of ricer/snake oil hits on Google.Swain andd Polydyn are often mentioned.

Thanks Rich, I'll contact Herr Schaeffer.

Piston/coating maker should have some guidelines. The coating if any has to be chosen with the cylinder material in mind. As you probably know, the stock engine comes with some kind of iron coating on the piston skirts.

Thanks Macaster, I had read about the iron coating on the piston skirt . I found no mention of using iron coatings in the aftermarket -all Moly/poly/teflon .

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Well, I haven't really kept up on the latest coatings craze. I can recall over the years, more years than I want to remember, coatings for pistons come and go. Some company developes a coating and wondrous benefits are touted and soon it is being applied to everything. Then the hubbub dies down and that's that until the next miracle coating comes around. Teflon has been around a while. There's a peeling risk IIRC, though of course no doubt by this time that has been improved upon. (Oh, there used to be teflon buttons used, too. The skirt was drilled and these buttons installed. The piston skirt never actually made contact with the cylinder wall.) In the case of the factory application of iron I think this is intended to be a temporary thing to facilitate proper engine break in to forestall piston to cylinder contact at least initially and for sometime afterwards. The best coating is really none. There is no issue about its proper application, it is one less thing to go wrong, come loose, flake, peel, or crack or otherwise degrade. The best solution is properly selected cylinder and piston material, clearances, finishes, and suitable lubrication and cooling (in the case of the Porsche engines provided by oil jets one for each piston). This all has to be addressed anyhow as no coating will ever eliminate the need for the above.

I recommend Embee Performance coatings in Santa Ana CA. I get any exhaust pipes coated inside & out with their thermal barrier coating They offer piston coatings & new JE pistons with the coatings, leading me to think they do most of JE's coatings, since they are local, but that's just my guess. When I worked at Stillen (2000) Embee did all their coating work. LN pistons used to come with coated side skirts on their JE pistons. Embee also does Mil-spec coatings.

Bill, Thanks for that suggestion.I really appreciate the time you take to help us noobs! The credentials you mentioned are impressive. They are conveniently close to other companies I already use :- Marine Crankshaft (David) and Costa Mesa R&D (Mr.John Edwards)

This can be a slippery slope.. Especially in regard to optimum running clearances and micro welding of rings to ring lands. The micro welding is more of an issue when piston crowns or chambers are coated, as the heat is reflected back to the top ring land. I move my top ring land down when using coatings, and I will often treat the lands differently as well. I also find that engines with crown and chamber coatings will often like much less total timing that non coated components do. My recommendations to a first time builder is to not create an unknown variable by introducing coatings to the mix. Keep it simple and work your way up- that's how I instruct my engine mechanical classes. Not all coatings are created equally... Some last a number of hours, others for a decade or longer. I've been using coatings since 1995, for my first decade I learned something new every time, generally the lesson was a hard one... You'll read lots about coatings in forums, but trust that it's mostly parroted information posted by some guy who wants to act like he's been there and done that; yet he doesn't even change his own friggin oil. Lots if those clowns out here on the net......

Thanks Jake. I find it very difficult to find reliable info on the subject.So much sounds like snake oil. So far, I had concluded the only factual measure was how long the company had been in business -so Poly-Dyn and Swain seemed interesting. I had abandoned 'ceramic' coating on the crowns because mine is not a turbo and runs a stock tune. The skirt scuffing prevention is interesting .I found positive references to "abradable powder coating" by U.S. Chrome & Line2Line http://www.enginebuildermag.com/2014...asting-longer/ But even after 90,000 miles my 3.2L pistons have all the machining marks on the skirt and crown ,so perhaps coatings are a minor issue on a stock engine ?

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If you are referring to me as the "he" my responses convey much the same as yours. I did offer that the piston maker should be able to offer guidance on what if any piston coatings could be used. While I didn't spell it out at the time, this should come with guidelines regarding any changes to the piston's geometry or dimensions or feature locations, like piston ovality, clearances, ring positioning, etc. The selection of piston coatings adds more complexity to an already complex process (correct and proper engine building) and I wonder for what benefit? You pretty much said the same thing, with your "keep it simple" and "slippery slope" comments. You specifically noted that total timing may need to be reduced which then I suppose could require a custom tune. Since 996 engines with piston coatings are rare the tuner would be likely breaking new ground to get this right. This doesn't fall into the keep it simple category. Furthermore, I note it is not like the stock engines are suffering unduly from the lack of proper piston (any internal engine part) coatings, unless the lack of piston coating has recently been added to the list of 996 engine failures. I'd say even though I don't change my own oil (nowadays) my comments and advice was pretty much in agreement with your's. Might add that during the time I was most actively involved in engine work engine coatings were a big topic. There was as I touched upon in a previous post the periodic appearance of the next big coating. Everyone was looking for *the* coating to work miracles: more power, better resistance to heat, less friction, lower emissions, better fuel economy or whatever. Lower emissions and better fuel economy drove a lot of interest into engine coatings as my direct involvement in engines started at just about the time the first oil embargo hit the US/world and concurrent with a big push to lower auto emissions. Automakers would have sacrificed kittens to improve fuel economy and lower emissions so engine coatings were a hot topic. And here it is decades later and still engine coatings on moving parts are primarily reserved for the very special needs of the competition community. While I haven't followed the coating technology as well as I did I have yet to come across any large automaker using any coatings on moving parts. (There have been some big improvements in metallurgy, surface treatments, to improve internal engine part longevity.) With all the concern about better fuel economy and lower CO2 emissions (which determine the tax or fee each car is assigned and strongly impacts an automaker's bottom line) you would think if any coating out there would offer any benefit its use would be wide spread and touted as much as stop/start, 7/8/9 speed automatics and so on. If the OP is interested, here's a link to a nice article that appeared in Hot Rod magazine that offers some test results of various coatings and the gains they provide: http://www.hotrod.com/how-to/engine/...#__federated=1 While the article is circa 2008 IIRC I think generally the results would be the same today. 'course the OP is welcome to go the coating route and report his findings. This looks to be an expensive task though as the engine would have to be tested with and without the coatings. And then there is the question of engine longevity what benefit (if any) this has or does the presence of the coatings introduce another failure mode.

This is hilarious but I'm sure it wasn't aimed at you Mac. You always try to help. But,, seriously, worrying about piston coating on a 320 (or less) HP M96 engine is laughable.

Macaster - that is by far the best factual link I have seen - thank you.High rpm and forced induction seem to be the features that may indicate some value to the coatings for road cars. Because it predates the "Abradable Powder Coatings" ,these newer products are not compared. I'll concentrate on optimizing the lubrication system and oils.

First off, it wasn't aimed at Macster, and if it was I would have stated that it was. I am a very black and white type of person, I say what I think, no matter the consequences. Sorry, you'll always get me at face value. Secondly, who in this thread has direct, hands on experience with internal engine components and coatings? You can read all the articles you want, and more than likely the guy writing them has less experience than you do. Believe nothing of what you hear, 1/2 of what you see and only about 5% of what you read. This is especially true today, when most every article has some secondary initiative behind it. I stopped submitting information and content when publications asked me to sway things one way or another, and a close friend of mine recently quit writing for a major publication because of similar issues. This is how I've learned everything I know about coatings. Some of that comes from building an engine specifically used for coating development. I have even built 1/2 of an engine with coatings, and the other half without and have even done the same thing with individual pistons, or chambers, or etc. Run a crankshaft with 1/2 the rod bearings coated, and the other half not coated and compare the results if you really want to see the differences. Induce knock/ detonation purposely to see which bearings are worn into their different layers first. This is what I do, and I do it all day long, unless I have taken a break to be a keyboard warrior. Then run the hell out of it, and vary the environment to include extreme conditions, mixed with normal old driving and see what happens. This is the only way to learn what works and what doesn't with a specific engine, or tune, or fuel, or oil. You don't read it from articles, and you don't learn it in a classroom. That said, in my experience the coating it's self isn't the biggest variable in regard to how well the longevity of the coating ends up. The surface preparation and proper coating that is to be applied is by far the biggest variable. Lots of the coatings are snake oils and lots of people report failures and enhancements falsely, because they don't know how to evaluate the data, or some variable was introduced that they didn't know, or think about. Variables are the developers biggest enemy when gathering data. In this photo I was testing a couple of different coatings. The engine lived at wide open throttle on the dyno for over 4 hours without being given a break, and with total disregard for its health, or even the test vehicle's health. I only shut it down when all the fasteners for the exhaust system had failed and we gained exhaust leaks that were going to start a fire. This is what we do, and this is how we learn what we learn. I enjoy every minute of seeing just how tough our components, and engines are, and how new things hold up, or how they fail. I fail more than I succeed, and I am fine with that. This engine didn't fail, its still alive and will have a punishment session coming its way after my next engine rebuild school coming up in early December.

Jake, Thanks for sharing your experience.Great photo and story. I promise to spend some of the money you've saved me on your book aka : The M96 Definitive Guide. Thanks for taking the time to improve the knowledge base on this Forum.

Hi Schnell Gelb, I have done 60k km's after the rebuild, and still runnig strong. So the method that we used, seem's to work well on M96 engines. There are lot's of race engine's here in Finland, that had have the same coating with good results. I mean better dyno results etc. Even some formula 3 teams use this method to coat their diff gears to get more top end speed. Oh, and I allso do change my oil's

Thanks for your info from the land of Valmet-assembled Porsches (and tractors and Saabs ).Anyone who follows your posts knows change your own oil-and more! I suggest there should be a special icon on this Forum to distinguish those of us who do engine rebuilds. Like in the military where you have a special badge on your uniform to designate 'Paratrooper' for example. Wayne at Pelican uses a wrench/spanner symbol to designate how difficult a job is. Oil change is one wrench, M96 rebuild is 10 ! So you have certainly one of the very few to have earned your stripes/spanners.

Jake, That is a cool picture! 996 a la F1 test.

"But,, seriously, worrying about piston coating on a 320 (or less) HP M96 engine is laughable." Porsche fitted pistons with coatings on all Boxsters. As previously mentioned by the oracle Mcaster ,it is an iron coating & is called Ferrocoat. Kolbenschmidt/Pierburg and MAHLE hold the patents to do this iron-spray coating of the piston-skirts. This is old technology and has been superseded by moly type coatings like PC-9. http://www.stle.org/assets/document/...rt_Coating.pdf

Those Boxster pistons were cast, not forged... The iron coating was used to create a dissimilar wear surface to allow for more favorable compatibility with Lokasil bores. Those coatings changed in their type and thickness over the range M96/ M97 production. These coatings also fail; which is the underlying condition which leads to cylinder scoring. This is especially true with engines that feature forged pistons from the factory.

Jake, Thanks for the info. So it seems some really knowledgeable experts think piston skirt coatings may be a good idea. I thought the Boxster S 3.2l pistons are forged? My source is Auto Atlanta who say "These pistons are as strong as the forged pistons found on "s" engines , but use a lightweight forged side relief design for improved strength while being lighter than the factory pistons." 3.2-3.4l Boxster 99mm Piston Set Boxster/cayman part #1069869 http://www.autoatlanta.com/Porsche-9...tons-srch.html And this from Baz at Hartech: "For sure an aluminium piston will not survive in a Lokasil bore without a coating of some kind" http://www.pistonheads.com/gassing/topic.asp?t=1320349 Just trying to learn all I can so I can keep up when I get accepted into the M96 class..