Ceramic coating pistons
Discussion
Anybody got any opinions on this?
www.camcoat.u-net.com/pistons.htm
Is this a reasonable preventative method of protecting against detonation without going mad and buying forged pistons?
Any opinions gratefully recieved
Paul
www.camcoat.u-net.com/pistons.htm
Is this a reasonable preventative method of protecting against detonation without going mad and buying forged pistons?
Any opinions gratefully recieved
Paul
Anybody got any opinions on this?
www.camcoat.u-net.com/pistons.htm
Is this a reasonable preventative method of protecting against detonation without going mad and buying forged pistons?
Any opinions gratefully recieved
Paul
Paul,
I rebuilt the engine on my Lotus Esprit this past summer, replacing the stock cast aluminum pistons with a set of forged aluminum pistons.
I did quite a lot of research into ceramic coating pistons and decided to have it done. The company I used was here in the states and they used a different material than shown on the link you provided.
The company I chose was Swain Technology in New York State. Swain is one of 3 ceramic coaters in the USA that are worth their salt. They have been in business over 25 years and have a proprietary material and coating process, are contracted by NASA and several CART & F1 teams.
I had occasion to inspect my pistons after 4,500 miles using a lighted bore scope inserted into the spark plug hole. The pistons look like new. I have noticed the slightest drop in operating temp, but as I also swapped the intake cam, increased the compression ratio from 7.5:1 to 8.5:1 and increased the turbo boost from 0.55 Bar to 0.69 Bar, I am probably making a little more heat as well.
They did a thermal barrier ceramic coating on the domes and a dry film lubricant (molybednum disulfide) on the skirts. Cost was $120USD for the set of four pistons. Turnaround time was 6 days. Here is their link...Hope this helps...Jim '85TE
www.swaintech.com/coatings.html
>> Edited by lotusguy on Friday 3rd January 08:10
For the record i raced a golf some years back and built a 16v 2 litre with Mahle pistons. these along with the head were sent to Camcoat and had the coatings applied. I did this as a precautionary measure against detonation as the Nitrous i was applying to the 188bhp engine would take it to 320 approx. So any help to deter/protect detonation was a bonus! On strip down the engine was untouched. Obviously many other factors contributed to that (correst air/fuel mixture, timing etcetc. the point i make is it was piece of mind.
350matt said: Lotusguy
What was the difference in power after the mods? as I have to say my expierience of this type of practice is that it's detrimental.
Thats not to say that you haven't got it to work of course
Matt
Matt,
My experience has been nothing but positive and that's after 4,800 mi. on the clock after completing the rebuild in mid-Sept.
I have not documented the horsepower/torque increase via a Dyno, but I have had several SE owners drive the car. Their comments, as well as my own experience, is that I can easily run with the SEs albeit breathing slightly heavier. One driver stated that my car was faster/more powerful than his SE.
My rebuild consisted of new alloy forged JE pistons - ceramic coated, raising the compression ratio from 7.5:1 to 8.5:1 (vs 8.0:1 for the stock HC motor), new mains and big-ends, a 104 cam (slightly higher lift: .412" vs 3.78" stock), a 3-angle grind, new valve guides and springs, rebuilt turbo (over-bored to accept a roller bearing) and rebuilt and recalibrated wastegate to allow 10lbs. boost over the stock 8 lbs., ceramic coated the exhaust manifold and exhaust (hot) side of the turbo housing, rebuilt carburettors w/ 0.62 idle jets vs stock 0.52's - left the mains alone, but will probably play with these in the coming season. Of course, all new seals and gaskets. Switched to a cooler plug. Have not experienced any problems w/ detonation or knock.
My car now comes on cam at around 2,800RPM vs stock 2,500RPM. This smoothes out the 3k RPM changeover and the power delivery curve flattens out through 6,800RPM. Idle is smooth, although the slightest amount of low end torque was given away in favor of high-end HP. I am very pleased and the only thing I would do different would be to port the intake side of the head, which I may do in coming years. Hope this helps...Jim '85TE
My actual concern is in the heat dispertion theory, surely is it much better for the piston to allow the combustion heat to travel away into the block and cooling jackets. Insulating the crown will retain heat and surely increase the risk of det?
Make any sense?
Thanks for the replys so far
Paul
Make any sense?
Thanks for the replys so far
Paul
Depends on cr and boost used.
I didnt apply it to gain any power, rather just to afford some protection from det.
Youre right about the heat being retained in the chamber and as we all know, heat is the enemy of a turbo motor.
The theory about coating the pistons is to simply keep the heat out of them in the first place.
Have to see how it pans out....
>> Edited by deltaf on Friday 3rd January 18:30
I didnt apply it to gain any power, rather just to afford some protection from det.
Youre right about the heat being retained in the chamber and as we all know, heat is the enemy of a turbo motor.
The theory about coating the pistons is to simply keep the heat out of them in the first place.
Have to see how it pans out....
>> Edited by deltaf on Friday 3rd January 18:30
I read that thermal coatings only give limited resistance to detonation but it will be longer then a non coated piston to be destroyed. Were only talking seconds, not minutes. In other words this means IMHO that there is a small safety margin that can be valuable to an engine running on the edge. Do most of us have engines that close to detonation? My other concern is that when a manufacturer designs a piston he allows for heat transfer from the crown down into the bosses and skirts. He then decides how much they will expand and does the final profile. If the heat is reflected back into the chamber, what happens to the piston below the crown? I have ceramic coated manifolds but they were still untouchable by hand so I have some doubts about manufacturers claims in the real world application. If I saw a piston manufacturer coating their own pistons I would have more confidence. I think it's a great idea for use on the exhaust valves. If money's not an issue then maybe it's just a bit of extra safety. Does anybody know which F1 teams do it? Keeping heat in the chamber is how we produce power.
>> Edited by boosted ls1 on Friday 3rd January 20:32
>> Edited by boosted ls1 on Friday 3rd January 20:32
Radar said: My actual concern is in the heat dispertion theory, surely is it much better for the piston to allow the combustion heat to travel away into the block and cooling jackets. Insulating the crown will retain heat and surely increase the risk of det?
Make any sense?
Thanks for the replys so far
Paul
Paul,
The whole purpose of ceramic coating my forged alloy pistons was to protect them from destructive heat.
One of the reasons for my rebuild was a piston which 'crowned' from heat cycling. When this happened, the piston pulled away slightly from the liner wall. This allowed combustion gasses to pass the compression ring and was able to melt the top edge of the crown and totally destroyed 1/4 of the ring land. After that, enormous blow-by of oil occurred.
Since temperature is a component of tensile strength, if you can run the pistons cooler, they will be stronger. Tests with the coating I used showed an operating temperature reduction of nearly 100°F. The alloy used in this piston has twice the tensile strength at temps 70°F lower than the normal operating temp.
As the coating is a heat insulator, the heat passes out of the engine through the exhaust gasses as well as being carried off by the coolant through heat transfer into the water jackets and the head. My temp gauge runs slightly lower than it did prior to the rebuild...Jim '85TE
Yeah im with Lotusguy.
Theres no way the likes of the headers will be cool enough to touch.Bbecause the coating on the pistons reflects/insulates it from worst of the heat, the material used in its construction runs cool enough to hold its strength.
Its the difference between boiling hot and very hot...ya cant put ya hand in it , but the difference is there!
Theres no way the likes of the headers will be cool enough to touch.Bbecause the coating on the pistons reflects/insulates it from worst of the heat, the material used in its construction runs cool enough to hold its strength.
Its the difference between boiling hot and very hot...ya cant put ya hand in it , but the difference is there!
boosted ls1 said: I read that thermal coatings only give limited resistance to detonation but it will be longer then a non coated piston to be destroyed. Were only talking seconds, not minutes. In other words this means IMHO that there is a small safety margin that can be valuable to an engine running on the edge. Do most of us have engines that close to detonation? My other concern is that when a manufacturer designs a piston he allows for heat transfer from the crown down into the bosses and skirts. He then decides how much they will expand and does the final profile. If the heat is reflected back into the chamber, what happens to the piston below the crown? I have ceramic coated manifolds but they were still untouchable by hand so I have some doubts about manufacturers claims in the real world application. If I saw a piston manufacturer coating their own pistons I would have more confidence. I think it's a great idea for use on the exhaust valves. If money's not an issue then maybe it's just a bit of extra safety. Does anybody know which F1 teams do it? Keeping heat in the chamber is how we produce power.
>> Edited by boosted ls1 on Friday 3rd January 20:32
Hi,
I hate to disagree with you, but it seems I do on at least a couple of points. I do agree with you that the thermal protection afforded by ceramic coating is limited with respect to detonation. That is correct, but thermal coating of pistons is not an effective means of controlling detonation. It's purpose is to lower the operating temp of the piston so maximum strength can be preserved. And, extra protection is just that - extra protection. If you are arguing cost/benefit there will always be some subjectivity to this as all pistons are not tested in all applications.
You ask if many of us run our engines close to detonation. This really isn't the point as detonation occurs mostly as a factor of compression ratio, engine timing, fuel octane rating and boost pressure. True, you can have detonation occur if you get on the gas, but this is mainly a product of timing changes and fuel flow due to the increased RPMs. Generally, the factors governing detonation are 'pre-set' with the driver having little influence over them. Also, the protection is not for excess stresses and heat at peak RPM, but rather the repeated heat cycling of normal operation.
As in my case, Lotus chose to remain with an alloy cast piston as used in the N/A S1 and S2 when they added the turbocharger. This cast piston didn't like the harsher conditions of the turbo environment, especially the heat. It begins to crown after so many heat cycles which translates roughly to 36k to 40k mi. My piston failure was not an aboration, but is a common fault of the early 'G' Turbos. It took a couple years production for the earliest Turbo models to accumulate this kind of mileage, so the fault didn't really manifest itself until 1984. To correct this, Lotus introduced the matched forged alloy piston w/ Nikosil alloy liner in the '86 model year. The fix for the early turbos was a switch to nikosil liners and forged pistons, but at $1,200/hole USD, this is cost prohibitive. But, a switch to a forged alloy piston mainly solved the issue.
Your anecdotal information regarding your coated manifold does not mean that your manifold isn't running cooler, just that it still operates above the temp where one can touch them.
You ask why piston manufacturers don't coat their pistons. I have a very good friend who worked extensively with Mahle, a premier piston manufacturer, as a consulting engineer. He asked the same thing. The reply he got was that they do recommend piston coating, when asked, for harsher applications. Pricing, unit cost and maintaining margins were prime factors in their not coating the pistons themselves.
Also, most of these coatings and application processes are proprietary, so an added license fee or royalty to production costs would be prohibitive. It was my friend's knowledge on the subject, along with a recommendation from a Top Fuel Dragster owner I know who convinced me that this is a good thing.
As far as which F1 teams use these coatings, the answer is all of them, but they don't all use the same coating or company. Team Jordan and BAR/Honda use Swain Technology, who did my coating, as do several CART and NHRA teams.
Finally, when you state: "Keeping heat in the chamber is how we produce power" I could not disagree more. Residual Heat is the enemy...period. Once all internal parts have heated to operating temperature and expanded, any excess residual heat is unwanted.
Sufficient heat to properly combust the mixture is introduced with each piston cycle through adibiatic heating from compressing the mixture with the turbocharger and further compressing it during the compression stroke of the piston. The spark provides the final amount of heat energy necessary to explode the mixture. Any additional heat has unwanted, and largely uncontrolled, effects on combustion timing, flame travel, fluid dynamics and total energy derived.
Having said all this, you must take all this in and use it to decide the cost/benefit to you. Some will see the benefit while others will not...Jim '85TE
>> Edited by lotusguy on Saturday 4th January 08:42
>> Edited by lotusguy on Saturday 4th January 08:47
Hi Lotusguy, I don't mind differing opinions and have read your interesting posting. My train of thought on this is that if the engine is designed correctly from scratch then it shouldn't need the pistons coated as there should already be a significant built in safety margin. Average performers can use cast pistons whilst other cars will go the forged route. I know nothing about Lotus (am learning though) but it appears that this was a fix whilst they utilised the cast aluminium piston which was adequate in a normally aspirated application but lacking as far as forced induction was concerned. I forget if the coating was carried out by privateers or Lotus but the weakness appears to have been cured by a forged piston which given it's density allows the transfer of a significant amount of heat away from the chamber and into the liners etc. The forging alone should drop temps by 100 degrees F appx. Most cast pistons have slotted skirts and more of the heat stays up top, (maybe this was the real problem). Did they have thermal slots in the skirts? Slotted pistons run quiet on startup because the heat is all uptop. Tell me, do Lotus coat the forged piston or are they happy with it as it is.
I accept that cost may be a reason why manufacturers don't supply pistons already coated but the likes of TWR or indeed any other mass producer of pistons could coat the pistons and this would allow tighter skirt running clearances and a load of other benifits. How many small block pistons are sold every day? If pistons came precoated I would be less sceptical/wary. Mahle already supply coated skirts for some high performance applications. A large manufacturer could develop a coating of they're own and really push the end product as they would surely accumulate sales from this addition especially if it were small block chevy.
As for my remarks about heat in the chamber, I meant that by keeping the heat in the chamber it was available to produce expansive power operating against the piston as well as being used to power the turbine instead of being wasted by transfer into the coolant system. I may be off track on this one as heat is a by product of combustion and I accept it's our enemy but it is a form of energy, we just need to control it to our advantage. If we can dump it down the pipe for the turbo then that's great.
I am open to ideas on these products, I think it's probably a good way to go but why isn't everybody doing it?? I have just bought 30 custom forgings. Should I coat them or not? Not sure yet so lets keep the debate going. I want my forgings to fill the bores properly and support the rings correctly. I may go for it though on my own engine as an experiment. Regards, Mike.
I accept that cost may be a reason why manufacturers don't supply pistons already coated but the likes of TWR or indeed any other mass producer of pistons could coat the pistons and this would allow tighter skirt running clearances and a load of other benifits. How many small block pistons are sold every day? If pistons came precoated I would be less sceptical/wary. Mahle already supply coated skirts for some high performance applications. A large manufacturer could develop a coating of they're own and really push the end product as they would surely accumulate sales from this addition especially if it were small block chevy.
As for my remarks about heat in the chamber, I meant that by keeping the heat in the chamber it was available to produce expansive power operating against the piston as well as being used to power the turbine instead of being wasted by transfer into the coolant system. I may be off track on this one as heat is a by product of combustion and I accept it's our enemy but it is a form of energy, we just need to control it to our advantage. If we can dump it down the pipe for the turbo then that's great.
I am open to ideas on these products, I think it's probably a good way to go but why isn't everybody doing it?? I have just bought 30 custom forgings. Should I coat them or not? Not sure yet so lets keep the debate going. I want my forgings to fill the bores properly and support the rings correctly. I may go for it though on my own engine as an experiment. Regards, Mike.
ive run the 2.2 lotus lump in many forms and states of tune(its really just a posh bedford van engine you know) and i have to say that you cant beat having a good quiality forged piston.
ran a couple of rally lumps at 11:1 cr(atmo) with coated pistons and the coating didnt last.
i put a good set of mahle forged pistons and had much better life.
but that said i also know people who swear by the whole coating pistons thing.
so all you can do is try it,if it works fine if its not great then it didnt cost arm+leg etc.
then you go out and buy good quality pistons.
no help i know but its just another persons experience to base a decision.
ran a couple of rally lumps at 11:1 cr(atmo) with coated pistons and the coating didnt last.
i put a good set of mahle forged pistons and had much better life.
but that said i also know people who swear by the whole coating pistons thing.
so all you can do is try it,if it works fine if its not great then it didnt cost arm+leg etc.
then you go out and buy good quality pistons.
no help i know but its just another persons experience to base a decision.
accident said: ive run the 2.2 lotus lump in many forms and states of tune(its really just a posh bedford van engine you know) and i have to say that you cant beat having a good quiality forged piston.
ran a couple of rally lumps at 11:1 cr(atmo) with coated pistons and the coating didnt last.
i put a good set of mahle forged pistons and had much better life.
but that said i also know people who swear by the whole coating pistons thing.
so all you can do is try it,if it works fine if its not great then it didnt cost arm+leg etc.
then you go out and buy good quality pistons.
no help i know but its just another persons experience to base a decision.
Hi,
Interesting to learn of your experiences. As you say, a person will have to appreciate the benefit before committing to a process. Some swear by it, while others do not.
The key is research and discussions on forums like this. There are a great number of coatings and application processes available. These range from a DIY kit in which you mix-up the coating, dip the pistons in it and cure them in your home oven (poor result) to very high tech plasma spray and ion deposition applications (very good results).
But, beware, 20 years ago there were basically 3 firms providing ceramic coating application, today there are nearly 75. Quite a few of these are charlatans, who's product does not stand up to their claims.
The company I selected uses a plasma sprayed application. To side-track a bit, plasma spraying shoots a plasma of the coating material at supersonic speeds in a vacuum onto the piston. This literally displaces molecules in the top layers of the piston and impregnates the ceramic into the piston rather than merely on the surface. This provides an incredible bond (150,00lb./in.² bonding force). Also, the composition of the ceramic, while proprietary, does contain a significant amount of aluminum so the expansion rate of the coating matches that of the piston itself.
I chose one of the initial 3 firms doing this process. They have a good reputation as well as having been a contractor to NASA for similar applied coatings for nearly 20 years. They use a plasma spray application process. I used another of these 3 firms to thermal coat my exhaust manifold, wastegate pipe and turbo housing, because their coating had better qualities in this application. They used a powder coating method followed by heat curing in a hydrogen oven. As I said, after nearly 5,000 mi. (of generally spirited driving, including track time) I am very pleased with the results.
I have inspected my pistons, using a lighted bore scope and found them in near pristine shape. I have found zero evidence that the coating has degraded or lost it's adhesion.
While I do believe this was a good choice for me, I cannot say that other firms, with different coatings or application processes, will yield the same results. I have never heard anything negative about the coatings applied by Swain Technology, and I did extensive research prior to having them coat my pistons...Jim '85TE
They probably saw the Aston and charged accordingly...a rich man and 'some' of his money are soon parted.
Lotusguy, re ceramic coating: l can understand the need for a higher level of application on the crowns etc... but as for exhaust manifolds, can't you just slap it on with a brush, ronseal style?
Lotusguy, re ceramic coating: l can understand the need for a higher level of application on the crowns etc... but as for exhaust manifolds, can't you just slap it on with a brush, ronseal style?
funkihamsta said: They probably saw the Aston and charged accordingly...a rich man and 'some' of his money are soon parted.
Lotusguy, re ceramic coating: l can understand the need for a higher level of application on the crowns etc... but as for exhaust manifolds, can't you just slap it on with a brush, ronseal style?
Well,
I guess you could apply it by brish. But remeber, my cast iron manifold was 17 years old and needed to be thoroughly prepped to receive the coating. Besides, HPC has a lifetime warranty against rust, not rust through, but any rust whatsoever. And, ny wife would probably have ceased to be so had I brought the manifold inside for baking in the kitchen oven...Jim '85TE
Hi again
Thanks for your help. After reading your comments and a bit more research into the thermal dynamics aspect I have decided to go ahead with the ceramic coating.
It should offer the pistons a bit of protection while the fueling/ignition+boost is set up and piece of mind for myself in the future.
Paul
Thanks for your help. After reading your comments and a bit more research into the thermal dynamics aspect I have decided to go ahead with the ceramic coating.
It should offer the pistons a bit of protection while the fueling/ignition+boost is set up and piece of mind for myself in the future.
Paul
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