Thermal Barrier Protection Coatings on Piston Dome and Skirts..Good or Bad Idea?

Determined · Determined's Garage

Hi everyone,

I'm planning to have my 3.2L Euro pistons send out for ceramic coating on the domes and lube impregnated on the skirts, has anyone had any experience with this. What were your results and is there anyone is California that can do this for me. I'm running high compressions and I have an MSD 6AL, I'll be running high octane or some race mixture...not sure yet. I don't want to have detonation and I can't afford twin plugging it. Comments are welcomed! Oh, what about thermal protection on the cylinder fins and/or other parts like valves, heads, springs, etc..Thanks a million!

Best Regards,

Alex

jpnovak · 03-14-2005, 06:54 PM

STart here

Ceramic coatings and dry film lubricants. your experiences?

piston top ceramic coatings

Determined · Determined's Garage

JP,

Thank you very much, it was very interesting material to read. So, how was your experience and how much did you pay? Who did the work?

Best Regards,

Alex

cnavarro · 03-15-2005, 04:56 AM

I would try Calico Coatings, as they have really fair prices, a great reputation, and actually do really nice work. There are some pictures of the kind of work they do on our web site at http://www.LNengineering.com if you click under type 1 or the porsche 356/912. I would do the crowns in combination with the ring lands (I prefer not to coat the skirts) then do the combustion chambers. I would also coat the intake ports (if doing FI) and the exhaust ports. Thermal dispersant coatings are pretty useless on aluminum, as in our tests they did nothing to affect the cooling on aluminum heads or cylinders.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

jpnovak · 03-15-2005, 05:55 AM

I have not actually applied the coatings yet. I just split the case on Sunday and took off the rods from the crank last night. Time to start cleaning and measuring. I am planning to coat all the wear surfaces on the engine with a dry film lube. This will include all the bearings, etc. I will be coating the combustion chamber, intake and exhaust tracts with a thermal barrier coating, ie piston crowns, head, valve heads.

You must be careful with the coating on the valve head to valve seat. they must not be coated.

I have heard great things about Calico. I will likely be buying from Techline. I have had lengthy discussions with Techline. They are very helpful and somewhat local in the event I have problems.

Charles, Why don't you use coatings on the piston skirts? Is it because of the tight clearances you run with Nickies? Which coating do you use on the ring lands? Do you use any of the oil shedding coatings on the underside of the pistons?

Determined · Determined's Garage

Thanks Charles and JP,

It sounds like this is going to be a learning experience for me and not to mention a fun one. I'll keep you posted on my progress, I am ready to send parts out and begin the final machining and reassembly process.

Best Regards,
Alex

cnavarro · 03-15-2005, 06:30 AM

Exactly JP, since we run real tight clearances and nikasil itself is very oileophillic (oil liking), there isn't a real high wear issue with the skirts. I'm pretty sure that the coating for the ring lands is a dry lube, but I may be mistaken. There have been reported incidents of ring land microwelding in cases where the crowns were coated but nothing was done to the ring lands, although I haven't had any customers experience this problem with the Nickies directly. I also agree with you JP about coating the sealing portion / tulip section of the valve, since I am weary about valve seating/sealing in longevity engines and recommend only thermal barrier coating the valve face (the side in the combustion chamber).

Although I was also weary about coating the bearings, I have seen first hand what our bearings look like when they have been run in severe duty applications after having been coated with calico's bearing coating and was quite impressed. You just have be be really careful and double check clearances everywhere when these coatings are applied, as they tend to apply .001" thick at a minimum which can cause other problems, unlike nanotech coatings such as DLC (diamond like carbon) that can be applied without changing clearances.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

jpnovak · 03-15-2005, 07:18 AM

Interesting note about DLC. My employer used to specialize in those films, although I am not involved on that side. I agree that they would be hard enough to prevent wear. Wouldn't they be cause wear on the opposing surface? I guess you could coat both wear surfaces. HMM this is not good. More ideas to float around in my brain.

cnavarro · 03-15-2005, 07:38 AM

We've tried the DLC coatings and they have worked great on wear surfaces such as rocker shafts, bearings, and even on valve stems and even though they are very hard, they have nearly immesurable coefficient of friction. Reason would stand that the same thing would go for the sintered silicon nitride we use for flat tappet lifters- since they are just a rockwell or two shy of diamond that they would kill camshafts, but it's the opposite- camshafts don't even wear enough to measure, even in full blown race motors after multiple seasons of high-rpm use with heavy springs/large amount of lift/radical ramp rates.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

jpnovak · 03-15-2005, 08:51 AM

Greta info here! Have you tried any coatings on rocker pads and cam lobes?

cnavarro · 03-15-2005, 08:55 AM

The DLC coating can be applied to the rocker pads or cam lobes, but not both, but it's mightly expensive (~$80 per rocker) or 1800 per cam! :-)

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

jpnovak · 03-15-2005, 09:26 AM

Thanks Charles, Time to go see if our plasma chamber is still hooked up to its powersupply.

I know at least a handful of rockers will fit inside...

James Renfroe · 01:08 PM

From what I have read, the later 911 piston/crown temperatures are held in check by the piston oil squinters. If the pistons crowns are thermally coated, the heat normally dissipated by the pistons will have to be dissipated elsewhere, like through the combustion chamber, exhaust port, and exhaust valve.

I think crown thermal coatings are ok to water cooled engines but not the air cooled 911s. I would follow porsches lead (as on the 996s) by thermal coating the exhaust ports and potentially the exhaust valves (not the stems of course). This puts more of the heat outside the engine (through the exhaust gas) so the engine can make more power and protect those exhaust valves!

As far as coating the wear surfaces, leave them alone. Thermal ceramic coatings are formulated for there thermal properties, they are not intended as a wear surface like Teflon.

Tinker · 03-17-2005, 07:51 AM

Looking through a recent Jeg's catalog I received, I noticed they are offering forged Mahle pistons that come with Mahle's 'Grafal' anti-friction coating to the piston skirts.

Tinker

beepbeep · 03-17-2005, 12:35 PM

I've heard few engine experts that claim that ceramic coating on the top of pistons is actually making things worse. Anti-friction coating on pistons skirts is OK, as it lowers the friction and thus wasted energy.

Unfortunately (accordin to theese gentlemans), ceramic coating on the top of the cylinder does insulate piston from the heat due to ceramic having low thermal conductivity, but it just leads to ceramic layer heating up much more instead, which leads to pre-ignition and detonation.

Proper non-detonating engine will never melt it's pistons, especially if oil-squirters are present. There are certain car engines with EGT's over 900 degree Celsius (that's 1650 deg. F). I've disassembled one of those (equipped with oil-squirters) and you could still read the numbers on the top of the piston.

I'm personally leaning towards this theory: coating piston crown is a waste of money and will lead towards more knock-prone engine (even though it might lower oil temperature).

YMMW

strokher racing · 03-19-2005, 09:52 AM

Ceramic coating has several benefits. It reduces hot spots on the pistons, improves flame travel, and increases combustion chamber temps. As for saying that is causes pre ignition that is the same thing as twin plugs. You just have to tune for things. I can tell you from running at least 10 engines with coated pistons etc that there is much more insurance on blower, turbo and nitrous engines for failure. My guys have pages after pages of testing results on this. The new thing is berrylium coating on the pistons instead of ceramic.

Eric Hood

strokher racing · 03-19-2005, 09:57 AM

Piston skirts are not done in ceramic or any kind of thermal barrier coating they are done in Teflon which is what is used on bearings, valve springs etc. Valve springs respond to being teflon coated more than anything. Springs usually last anywhere from 3-6 times longer than uncoated springs. Coat springs!

Eric Hood

Determined · Determined's Garage

My pistons are back, ceramic tops, lube on skirts, lube on wrist pins, and oil release on bottom. I can't wait to try them.

Alex

strokher racing · 05-17-2005, 07:47 PM

Alex how much did that cost you in your area?

Eric

Determined · Determined's Garage

Eric,

Actually, I had them done by Stan Wilder in Texas. He did a fantastic job and was very reasonable on pricing, I highly recommend him. No to mention he was very fast and excellent communication. Everything I said I had done was only $198.00.

Best Regards,

Alex