Ceramic Coatings

[Chris Wright, Sydney]

Hi Guy, and all,

Here's a conundrum which just occurred to me - We all know about the benefits of aluminium cyl heads over cast iron; two that spring to mind immediately are 1) lighter weight and 2) better heat conduction to the water galleries allowing higher compression with less chance of hot spots in the combustion chambers leading to pinging.

The conundrum is this - 1) does not ceramic coating of combustion chambers reduce the ability of the cyl head material to conduct heat to the coolant galleries, and 2) would this lead back to more likelihood of hot spots and pinging? If so, it would seem a tremendous retrograde step.

A warm fuzzy feeling to the first person with the correct answer!
thank you,
Chris Wright
Sydney

[trickymex]

The only experience i have had with ceramics in engine was with small (10cc) two strokes used in model boats, but that was not ceramic coated, it was a full on ceramic piston and liner, running on a methanol based fuel

Comparing them side by side, the main difference was the normal ABC(Alloy piston,Brass liner,Chrome plated) design would finish a run with a temp of around 100 degrees, and the ceramic piston and liner version ended the run with with a temp of around 60 degrees

This was an air cooled engine and the performance difference was almost nothing about 1mph to the ceramic setup

So it disipates heat better for sure but it did'nt seem to make all that much difference to performance

Ricky

[robert kenney]

IThink a session is needed to fully understand the effects thus benefit of ceramic coating in a modern piston engine.
I am not an expert but have done a fair amount of research on the subject and can't say how this would equate to racing totally.

The implementation of piston coatings began in the very recent past as a way to increase the thermal efficiency on an ICE (internal combustion engine) by reducing the amount of heat energy lost in to the cooling system and oil. The coatings have a 2-fold effect on this.
1) The coatings are less thermally conductive than bare aluminum and act to insulate the flame from loosing as much of its energy to the surrounding metal
2) The coatings can also be made to have a very highly shiny very durable surface finish. This lowers the emmisivity (the measure of how efficiently a surface color or finish transfers IR infrared energy). Black and satin = the greatest to chrome and shiny the lowest. This also lowers the heat absorbed and reflected back in to the combustion chamber.

Both of the above effects act to decrease fuel consumption and emissions both desired in today’s greener world. They also act to decrease the piston's alloy temperature, oil temp and coolant thermal demand (when combustion chambers and cylinder walls are coated)

Personally I have been asked by potential customers requiring high performance boat power plants to add this if prudent. The info I gather supports applying it to their engines. You can investigate the cutting edge piston MFG'rs for their opinion on the many different options.

As for racing and propensity for detonation many believe the ceramic-coated surfaces will be cooler due to the reduction in IR absorption and help fend off detonation.

As usual the proof is in the numbers and only real world testing will prove or disprove the preceding. Many auto manufacturers are using special coatings inside their engines to help meet more stringent emissions requirements. So logic will tell you this does work.

I will apologize in advance if I have posted in GC/ QA out of place. I didn't notice the form until after posting. If it needs to be moved or so on I understand.

Robert

[1NRO]

It's my understanding that heat is still absorbed like an uncoated part but the ceramic coating maintains the combustion temperature for a longer time. I'm not convinced they'd be much good in anything other than mega spec and must loose efficiency when there is a layer of soot. Bling or genuine pursuit of a final few percent?

Nik

[Guy Croft]

Coat any moving engine parts at your peril. It's such a harsh environment in there. Yes, I know most of the techniques and application methods..

That's all I personally really want to say on this.

GC

[superbike]

I saw a ducati combustion chamber last year wich was coated by firm x. I did not rate it at all . It was a mess , Aluminum melted behind the coating. Even the 190 hp 15.1 compression ducatis that raced in BsB last year were not coated . This tells me if there not doing it theres no need for me to do it either. However it may have its place but im not sure where ?

[1NRO]

I think it has found a place in engines that aren't expected to last. Counted in seconds. So much fuel its on the point of locking solid. I have seen a picture of a connecting rod that was on its way to the bin with the coating all peeling off, the fact it had held together long enough to allow dissassembly was an improvment in the eyes of the builder! He'd not been far. Like everything, it will evolve.

Nik

[robert kenney]

I think it has found a place in engines that aren't expected to last. Counted in seconds. So much fuel its on the point of locking solid. I have seen a picture of a connecting rod that was on its way to the bin with the coating all peeling off, the fact it had held together long enough to allow dissassembly was an improvment in the eyes of the builder! He'd not been far. Like everything, it will evolve.

Nik.
Interesting to see a coated Connecting rod in a motor. Not sure what one could gain? Claims have always been thermal in nature.

I do know N. Arias personally and they have done testing in the realm of component (piston) coating. Also offer crown / skirt coating for special applications.

I have personally seen Bonaville motors equipped as such. Lasting also. I have been in many 8000+hp Nitro burning engines and have never seen any coated parts at all. You are correct in the fact that they do not last long. If a rod was fortunate enough to survive long if is standard procedure to scrap after 5 passes (25 total seconds at power) regardless of condition due to the fatigue life
of aluminum.

Robert

[robert kenney]

A quick follow up on this subject.


Yes, thank you for the clarification of the information you found. Surface treating of steel wear parts like the piston pin you found is common however the connecting rod was bare aluminum. That company has developed a spin on the tried and true carbo nitriding process. This process is fairly common on crankshafts/ piston pins and cams ETC. Sounds like a surface hardening where the metal surface is chemicaly altered to enhance durability.

I think the "art" for lack of a better word of specialized coatings is a growing trend in the realm of restricted class racing. Like many classes of drag racing. The governing bodies like NASCAR and NHRA keep taking things away from teams in an attempt to slow them down but the winner is always the fastest so they keep pushing the limit of parts and the like. I think they are working to get any edge possible. Coatings are surly one place to pickup a hundredth of a second in ET.

A good example is TOP FUEL / and FUNNY CAR in the NHRA. A number of years ago they figured that in they restricted the fuel pump size, nitro/methanol ratios and blower size and drive ratios they would improve the sports safety. Well as history would have it they are still breaking records along with a slew of parts. Still going faster and faster and guys are dying Scott Kaleta being the latest. Now the big guys are said to be pushing 10,000 HP on less fuel and less manifold pressure. If a piston will tolerate 1/2 second more of detonation or extreme temperature you may win.

Robert