Author Topic: piston coatings  (Read 4724 times)

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Offline Vishnuatepork

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piston coatings
« on: February 08, 2011, 08:02:39 PM »
During my engine re-rebuild, it has come up several times with various marketing claims.  Either dry film moly ( on the skirt), and or ceramic coatings on top and bottom of the piston.  Its only 150$ for both pistons.  But that 150 could be spent else where....if there there is no benefit.


Thoughts, comments?

usage;
High rpm (10k) V twin motorcycle. 86mm  bore
suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline Anvil*

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Re: piston coatings
« Reply #1 on: February 08, 2011, 09:37:05 PM »
*snip* Either dry film moly ( on the skirt), and or ceramic coatings on top and bottom of the piston.  Its only 150$ for both pistons.  But that 150 could be spent else where....if there there is no benefit.

Thoughts, comments?

usage;
High rpm (10k) V twin motorcycle. 86mm  bore

OK, sounds like Harley/Indian territory, likely air-cooled... If so and normally aspirated on gas, I'd likely skip the ceramic coat on the piston, but I'd keep the lube layer on the piston. Water-cooled with oil squirters, again normally aspirated on gas I'd skip both if the budget was tight. As you add pressure and heat saving the piston becomes harder to do and anything you can do to save the piston for the return run gains value. Oil squirters, water injection, dry-lubed piston skirts, and thermal barrier coatings (basically in that order). So if you're running blown-fuel... do it all, bring luck, and keep very detailed tuning notes.

Hope that helps. With more engine/vehicle details, someone here likely has practical experience with your setup.

Offline wobblywalrus

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Re: piston coatings
« Reply #2 on: February 09, 2011, 01:21:27 AM »
South Bay Triumph coated the pistons and gudgeon pins on the Triumph with some sort of special something.  They strongly recommended it after I told them I would be using the motor for LSR.   

Offline Vishnuatepork

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Re: piston coatings
« Reply #3 on: February 09, 2011, 03:29:36 AM »
Sorry for not filling in the other details, I forget the options available.  I am going with gas and it is a water cooled engine (Suzuki 800 series  from the intruder, boulevard, c/m/s50 series).  12:1 CP pistons, Carrillo Rods +,+,+,+,+,+other stuff, but I dont think the other stuff is pertinent.

I have spent the better part of the afternoon today trying to weed out marketing jargon and trying to find actual numbers.  I saw on one website where it was used for machinery in high pressure high temp, but never did they quantify it.  I want actual numbers... I do see the possible benefits but it astounds me that no one has numbers you can actually compare.

Cheers
Alan
suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline grumm441

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Re: piston coatings
« Reply #4 on: February 09, 2011, 05:12:47 AM »
We had both the ceramic and the dry film moly on our pistons.
The ceramic has a higher melt temp than the aluminium and I have used both with good results in two stroke bike engines where
customers were chronic wreckers

This is the first car engine I have used it in, but I have seen good results in a buddies turbo charged Gen III 350
Having said that I should mention that the guy doing the coating is a friend of mine and sponsors our car
We also had the exhaust system ceramic coated, which looks great, to prevent corrosion.
G
Chief Motorcycle Steward Dry Lakes Racers Australia Inc
Spirit of Sunshine Bellytank Lakester
https://www.dlra.org.au/rulebook.htm

Offline JohnLevie

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Re: piston coatings
« Reply #5 on: February 09, 2011, 10:57:36 AM »
The $150 it costs to coat is cheaper than one failure.  Even if you don't see the immediate results, it is good insurance against that urge for the next leaner jet.  It allows for plug readings that tell you that you are to lean, not the piston.

Offline johnneilson

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Re: piston coatings
« Reply #6 on: February 09, 2011, 11:06:53 AM »
I know this will raise an eyebrow or two, but, it does have merit.

In discussion with some of the folks at Cosworth, coatings are a band-aid, if you need them then something is wrong. Materials, lubricant, clearances, configuration, etc.

Personally, I have found this true in high revving 2/ motors (up to 19k).

Just something to ponder........

John
As Carroll Smith wrote; All Failures are Human in Origin.

Offline JohnLevie

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Re: piston coatings
« Reply #7 on: February 09, 2011, 11:42:04 AM »
I wouldn't call it a band-aid.  More like a condom.  You know there is always the possibility of a failure, but you sure are happy when everything goes as planned.
« Last Edit: February 09, 2011, 11:43:51 AM by JohnLevie »

Offline Vishnuatepork

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Re: piston coatings
« Reply #8 on: February 09, 2011, 07:30:32 PM »
I know this will raise an eyebrow or two, but, it does have merit.

In discussion with some of the folks at Cosworth, coatings are a band-aid, if you need them then something is wrong. Materials, lubricant, clearances, configuration, etc.

Personally, I have found this true in high revving 2/ motors (up to 19k).

Just something to ponder........

John

John,
 Interesting  way of looking at it.  I think I will go ahead with it.  Small price to pay for a very small condom.  Keeping in mind you have merit to your veiw, we (most LSR racers) dont have the resources of Cosworth.  I know I dont!!!!!!!  Having already ate 1 set of pistons, I cant afford any more trial and error.  This time I am using a race mechanic and getting it dialed in before putting a leg over it....
suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline RichFox

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Re: piston coatings
« Reply #9 on: February 09, 2011, 07:37:57 PM »
Some years ago I wa both running a 270 GMC turbocharged on gas with cheap cast pistons, and working in the Plasma spray dept. At the airline. I sprayed ceriac on the piston tops after loosing a few and it worked great for me. Then I stepped up to Arias pistons and they also worked great for me.nnn

Offline wobblywalrus

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Re: piston coatings
« Reply #10 on: February 11, 2011, 01:31:39 AM »
There are a lot of different coating types on the market.  Are there any independent and scientific studies comparing them?

Offline Vishnuatepork

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Re: piston coatings
« Reply #11 on: March 07, 2011, 03:28:20 AM »
I have sent out alot of emails on this topic, and I wanted to share my findings.

In the end I have no idea what to do, but some here may find the items I bring to the table useful, or at least questionable.

These two appear to be viable, as they are not actual paint, as most coatings are....

http://www.wpctreatment.com/index.htm

I dunno if their claim that it makes things (alu) harder. Please feel free to comment. WPC seems to be just about the only people that do this stuff.  Snake oil?

and

DLC Coatings or Diamond Like Carbon Coatings...

http://www.bekaert.com/~/media/Files/Download%20Files/Automotive/Cavidur%20on%20racing%20engine%20components%20brochure.ashx


lastly a whole article on coatings.

http://www.highpowermedia.com/mall/ret/RET047_Sample.pdf

Interesting on what you can do for rads.....
suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline wobblywalrus

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Re: piston coatings
« Reply #12 on: March 07, 2011, 11:50:49 PM »
It would be a simple test in a V-8 engine.  Simply coat every other bearing, rod, piston, valve, etc.  Then race the engine, tear it down, and compare the parts. 

Offline F104A

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Re: piston coatings
« Reply #13 on: March 08, 2011, 01:20:42 AM »
I run a 258" Hilborn injected Chev. I did the coatings on my piston skirts and valve stems. I coated the tops of pistons and valves with ceramic. I polished the entire crankshaft so it looks like chrome then cryogenically treated the crank. I normally shift at 8000 and it has held together quite well over the 10 years I've run that engine. I recommend the coating.
Ed

Offline Vishnuatepork

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Re: piston coatings
« Reply #14 on: March 08, 2011, 10:37:07 PM »
Well today I finally got to speak with someone whom could actually answer my questions!  

I talked with a Head Tech at Swain coatings (only after telling 2 preceding ppl my questions and lsr plans). As well as a tech at Intellectual Alliance.

To paraphrase, in particular order:

ptfe (teflon based) products.  Here he had very strong cautionary words.  Essentially ptfe (teflon is a dupont name but...its the same stuff) is oil phobic, so oil wont stick to it.  Not good for a skirt coating, obviously.  {{Now he didnt say this but these are my thoughts on the subject of teflon - teflon is a paint product. It can be applied via spray or silk screen. Caution should be used in using it (paint) in side the engine close to the piston, as high heat can degrade the paint to point of uselessness.  }}

molybdenum disulfide skirt coatings -   Much better for skirt coatings. Even though moly is not hard it is tough and has very good lubricity.  {{ I havent talked with or discovered how it can be applied, but my cautions for paint remain.  Heat degrades them.  I will continue my search for application methods.  If plasma is available I would think it is the better method.}}

skirt coatings- general comments from the tech at Swain.  frequently not alot of measurable benefit is achieved. If proper tolerances are created and lubrication are present, it shouldnt (friction) be a big issue.  WHAT skirt coatings do, do is to create a barrier when the aforementioned tolerances and lubrication are absent. In addition he said that only in very highly stressed applications are benefits observed and needed.

dlc coatings or Diamond like carbon - *here I want to paraphrase both the conversation with swain tech, and a conversation with Intellectual Alliance in Vaughan Ontario* (Intellectual Alliance provided me with some links to a scientific journal from 2006 that talked about measurable results - New Diamond and Frontier Carbon Technology Volume 16, Number 4 -2006 ).

ok, DLC coatings are very hard and require special surface prep. nearly mirror smooth surfaces or else when the DLC is grown (its a crystalline structure) it will wear what ever it mates to like sandpaper, only harder. Period.  That makes surface prep $$$. I had linked to beakert.com previously and they shown pistons (highly unlikely outside of designed specs due to their required prep) but valves are possible, but if the valves require something with a "super low coeffiecent of friction", (then there is likely a design issue with normal lubrication) , but I didnt realize that the pics in Beakert too should have been  regarded as marketing (ooooh look at the farkle..).  In the tech article I mention above, they do talk about upto a 40% gain/savings in torque in the valve train when dlc is applied to the shim/bucket.  That being said I dont recall what the input torque was (<4kg/m?).  But if the potential input is large, like from a large V8 with cam driven gears the savings may not add up to much at all. It must be noted that their best results were achieved using an ester based oil.

It was suggested that dlc be applied to the rings, as they are the biggest contact point (for friction) in the piston assembly.  Interesting thought.




lastly ceramic coatings - now this is more application specific.  Keep in mind that my project is intended for the Mojave mile not a long track or short track salt racing, nor is it going to be running on race fuels, just pump gas.  So with that being said a ceramic coating on the top or bottom likely wouldnt be of much use.  The ceramic helps prevent heat build up and with run durations of (possibly) under 3 min, I would not see any net benefit.  For guys running longer with lots of power (ie  heat potential) then it maybe of benefit.  Or track racing where it is constantly being run at wide open throttle.  Then maybe, but not me.  


Read the article it really is quite intriguing.  If you want a copy and cant figure out how to find it, then pm me.

Cheers
Alan
« Last Edit: March 08, 2011, 10:52:44 PM by Vishnuatepork »
suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods