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Benefits of ceramic coating chamber parts

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SammyDaFish

SammyDaFish

Mechanical
Apr 1, 2002
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Does anyone have some information on actual test results and hard data in regards to ceramic coating combustion chamber parts? I understand that the coating increases thermal efficiency, but by how much? I plan to have my piston crowns and the chamber area of the head coated. My understanding is that the insulating properties of the ceramic will reflect the heat energy back into the fire, letting it extract more energy out of the fuel. HC emissions should be lower because you reduce the rapid cooling that affect parts of the mixture in contact with the chamber walls. Exhaust gasses should be hotter and therefore lighter, this should increase flow through the exhaust and therefore turbo spoolup (plan to coat the header, turbo housing and downpipe). Under hood temps and general operating temperature should be lower because less heat energy will be absorbed by the engine and exhaust parts. This should increase oil life and give the ability to run thinner oil. Am I correct in my thoughts here? How material are these gains? What about ceramic as an aid to reduce friction? Some piston manufacturers offer ceramic-coated skirts. How does this help? Could the same principle be applied to maybe valve stems to reduce valve train friction? Again, how material are the gains? Where can I read about research done on the topic?

Thanks
 
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Sammy, re your specific questions and thoughts

(I understand that the coating increases thermal efficiency, but by how much I plan to have my piston crowns and the chamber area of the head coated. My understanding is that the insulating properties of the ceramic will reflect the heat energy back into the fire, letting it extract more energy out of the fuel?)

I don't have quanitative figurers, and I suspect that 100 tests would give 100 different results, but I do know that the ceramic coatings must go on very thin so as to avoid flakeing off. This means that even though they might be very good insulators, they are only effective for a very short time, so they in efect delay the heat transfer dureing combustion, until the next fuel charge comes in and cools everything.

(HC emissions should be lower because you reduce the rapid cooling that affect parts of the mixture in contact with the chamber walls.)

I don't think you are right on this one, as even though the re is less heat lost from the combustion chamber, that which is lost is concentrated at the surface in the ceramic coating.

(Exhaust gasses should be hotter and therefore lighter)

Once again, not strictly true. If you heat a gas in an unrestricted environment, it expands and reduces density, but if you heat it in a closed environment, it cannot change volume, therefore cannot cannot change density, but it does increase in pressure. A combustion chamber is an alternating, closed, limited variable and opened by a very restrictive path environment, so it is realy quite a complex dynamic situation, but basically, the extra power comes from building higher pressurs in the chamber and higher pressure difference accross the turbo, thereby increasing gas flow and increasing turbo spool up speed

(plan to coat the header, turbo housing and downpipe).

I agree with coating the header and turbo, but the downpipe is probably not really worth it, except for cosmetics.

(Under hood temps and general operating temperature should be lower because less heat energy will be absorbed by the engine and exhaust parts.)

Wrong. The heat is not absorbed, but actually left in the combustion/exhaust gas, which allows it to be carried out the exhaust pipe, rather than released into the water, oil and air around the engine.

(This should increase oil life and give the ability to run thinner oil.)

Yes and no
If you reduce oil temperaturs enough, so as to need a change to it's viscosity rateing, so as to maintain the optimum viscosity, you end up back at the optimum viscosity, which is where you started, no net gain, except dureing warm up. Re oil life. the main limiting factor determining oil life of any good synthetic oil, is Total Base Number, not resistance to oxidation, so the oil change interval is not really changed. The main advantage of a good synthetic here is that being more resistant to oxidation, they do not carbonise as much in the area of the turbo bearing, so a cooler turbo will be less prone to the oil lines and galleries in the turbo becomeing blocked with chared oil breakdown deposites.

(What about ceramic as an aid to reduce friction? Some piston manufacturers offer ceramic-coated skirts. How does this help?)

See techline coatings site for this info

(Could the same principle be applied to maybe valve stems to reduce valve train friction?)

The gains are small, especially relative to costs, that is why most serious race cars use a variety of ceramic coatings, but auto manufacturers rarely use them.

One extra advantage of coating the turbo houseing is that it helps reduce cracks in the wastegate seat area (as does polishing and removal of stress risers). Cracks at the wastegate seat, caused leaks, severly damage boost build up, thus so greatly increasing lag times.

Regards
pat
 
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The University of Michigan (Assanis), among others, (check SAE) has done some fine work in this and related areas... and I can say that one has to understand the "system" as opposed to just a single component. My opinion is that unless an entire system solution is followed (assumingit's well-planned) it's a waste. And there's a lot of hype out there. Seem's that everyone wants to get some coatings for this or that...
 
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By chance while searching for another document I came across the one below, which I previously sent to this forum on another thread :

The heat insulation by ceramic coating of pistons and cylinder head combustion chamber surface in a diesel (and I suppose in a SI engine as well) doesn't directly affect its efficiency : it lessens the proportion of heat lost to the coolant and increases the proportion lost in the exhaust. So, unless some energy of the exhaust is recovered, the only gain to be expected is a reduced power needed to for the cooling fan and coolant pump.

If the engine is turbocharged, heat insulation should improve somewhat low end boost pressure and torque, but a much more efficient way to go is turbocompounding. Turbocompound engines include the Wright R-3350 Turbocyclone of Super-Constellations and DC 7s, the fabulous Napier Nomad and latest 12 liters 6 IL of Scania and Volvo. Caterpillar recently released on the web a document showing 10% efficiency gain at full power with electric turbocompounding along with the suppression of turbo-lag and greatly improved low-end torque:
More text at:

This thread remained me of the Eslbett engine. An impressive paper from Ing.Ludwig Elsbett was published in MTZ 42 (1981) 3, p. 99-105: "Entwicklung eines Dieselmotors mit wärmedichterem Verbrennungsraum". They still have a webpage:
Unfortunately, more than 20 years latter this remarkable development still seems almost completely unknown, all the other papers on the subject being in German. But the Google translator's efficiency is alright…

Cheers
Aorangi
 
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Above about 2400°F NOx emissions begin to increase
substantially. That's always a problem if you are
building a production street legal engine in areas
subject to emission control laws.

Nitrogen (N2) from the intake air is present in the
combustion chamber at concentrations around 75% to 78%
as a triple bonded diatomic molecule. As the combustion
temperature reaches about 2400°F and above, more of the
N2 molecules dissociate and compete with the fuel for the
attention of the available O2 molecules. That forms more
NOx which is an endothermic reaction meaning it absorbs
energy from the combustion process which is no longer
available to expand gas. So clearly, like everything else
inside an engine, there are limits which beyond a certain
point more isn't always better.

As the combustion temperatures/pressures rise, there is
always a point where detonation begins to occur if the
fuel octane is insufficient. Detonation, in addition to
destroying engine parts is famous for NOx production.

Hope this helps,

Chumley

 
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Aorangi said, in part:
"Caterpillar recently released on the web a document showing 10% efficiency gain at full power with electric turbocompounding along with the suppression of turbo-lag and greatly improved low-end torque:
"

The current url is Tantelizing rather than informative, as the pdf is the slides without the accompanying text, which I'm sure contained the information detail.
The associated (which worked for me) gives a possibly more accurate view of the current situation, as it refers to the areas of difficulty that had been identified. I realise two years have passed, but the reader begins to understand why the technology isn't yet available in the Dealers forecourt, in my view.
Cheers, David.
 
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Pat, thanks for your response. And thatnks for the links guys. I read through all the info on the sites, but unfortunatly, it's more semitech sales pitch than actualy test data. Nowhere yet have I seen actual quantitive numbers. It all sounds good though. Basicaly I'm still where I started though, knowing about tons of theoretical gains from it. Techline had a lot of good info on coatings reducing wear, but that's not as much of a concern to as the chamber coatings. Though I might coat my bearings to reduce frictional losses (again something I've seen no quantitive data on). If anyone can direct me to an SAE paper or something of the sort I'd really appreciate it. I can't imagine that coating manufacturers can sell this stuff without ever testing it. (I'm contacting some manufacturers to try and get info from them).

Chumley raises a good point here. Even with the use of EGR to reduce combustion temperatures, would ceramic coatings be enough to negate it's effects? I'm still looking for more information on the subject. The Caterpillar idea sounds great, especialy for large diesel engines, but it's simply not practical in my application and I don't see how it would really be an efficiency gain in gasoline cars, especaily becasue the engine and turbo speeds are so much higher than diesels.
 
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All,

OK so it sounds like a no net gain yet in the latest engine masters shootout coatings were credited with gains that lead to the win. Now how about a twist, what do you think will happen with an air / oil cooled motor say Porsche???

PFM
 
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Has anyone read any of the following SAE papers? Do any of them give the type of information I'm looking for?

900402
Ceramic Piston-Cup--Design and Testing

892495
Reinforced Composites for Piston Engine Components

891984
Exhaust Heat Containment System

91A105
Ceramic Coating for Aluminum Engine and Components

91A108
Microarc Oxidization Process--A Perspective Technology Used for the Obtention of Qualitative Ceramic Coatings

911719
Ceramic Coatings for Aluminum Engine Blocks

900968
Metallic-Ceramic Coatings as Replacements for Cadmium Plating

870720
Potential Use of Ceramic Plasma Sprayed Coatings in Combustion Engines

If anyone has read or has access to any of these papers, I'd love to hear about them. Do SAE members get a doscount on papers? I let my membership lapse a few years ago. [neutral]
 
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rmbuilder, did you happen to find any dyno results showing improvements on the coatings? Have you done business with Swain Tech? So far I've been able to find the most information on people using them, still though, no quantitative data :(
 
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Sammy,
Actually Swain is about 10 miles from my house. Let me call Dan out there and see if I can get some solid quantitative, apples to apples data to specifically answer your questions. I know that Joe Sherman was mentioned in an earlier post regarding his win at the Engine Masters competition and he gives significant mention to coatings contribution to his victory. I will enquire about both friction and thermal and get back to you ASAP.
Hope this helps,
Bob
 
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An inordinate amount of research was done in ceramic engine development throughout the 80s. By generating high temperatures and maintaining them in the combustion chamber, the thermodynamic efficiency of the combustion increases (less heat required from the combustion to sustain further combustion).

Some useful books:





If you need more specific advice, my email is:

jintrater@matmod.com
 
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Toyota has used a ceramic coating on the piston crowns on the 4agze engines, I believe the purpose being mostly to lower the oil temperature somewhat and raise the pistons heat tolerance.
 
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Pat, not on the 7M-GTE, that's the application. Possible the 1J or 2J engines as they were a little more expensive. There was a special production JDM only 7M-GTE that might have had it. I'm busy now, but I'll post more about the application tomrow. Thanks for the references so far... what do you think are the chances I'll find those book in a library? Probably should check a univercity library huh.
 
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I only ever pulled one down & it had ceramic coating, but I don't know the full history, so it might have been modified, or it might have been a special. I only learned as much about them as I needed to keep the head gaskets in mine at 10# boost

Regards
pat
 
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David Vizard have dyno results on ceramic coatings in one of his books. As I remember he states approx. 5% hp gain by coating piston crowns and 10% by coating piston crowns, valves and combustion chamber in a typical US V8 engine. He is an independent engine tuner and parts tester.

HOW TO BUILD HORSEPOWER, VOL.1, ISBN: 0931472245

regards
Ragnar
 
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