got rid of pinning by ceramic coating piston tops

[arek]

Well, I thought I'd share this. V11 was pinning bad, then got a little better with TP adjustments and TB synchronization, but never went away. Then, I pulled the heads and while having it all out, I coated the stock piston tops with ceramic coating in hopes minimizing the pinning. Well, guess what ... it is GONE. No matter how much I open the throttle under load, I cannot hear any pinning whatsoever. originally I thought that Mike Rich's pistons was the only solution to get rid of it, but this certainly works - and the cost ... $70 Cheers

[luhbo]

Could you provide a little more details, please?

 

Hubert

[gstallons]

When you say "pinning" I hope you mean "pinging" or spark knock. You had the dome of the pistons ceramic coated, how is this process performed?

[Guest ratchethack]

Coated piston crowns have been increasingly popular with forced induction and nitrous engine builders for years. Many of 'em swear by the heat reduction benefits to pistons, as evidenced by reduced discoloration of new pistons underneath compared to non-coated new pistons. The theory seems to be that non-transfer of heat into pistons is converted into usable energy output in the combustion chamber. Of course these motors are typically torn down for complete rebuild after a handful of passes thru the traps at the strip -- That's a useful operational life of miles in the low single digits.

 

As for benefits for a previously pre-igniting or detonating motor for the road??

 

This is just me, but seems more'n a tad far-fetched. A newly de-carbonized combustion chamber after heads-off work can be expected to ping significantly less than before, without any coating. A good hard anodizing accomplishes the same thing as ceramic coatings. Unlike coatings, hard anodizing can't flake off, and every quality piston made is already hard anodized.

 

I'm open-minded enough to reserve judgment pending credible long-term study analysis on the road over many tens of thousands of miles -- of which there doesn't seem to be any, as far as I can tell.

 

Somebody please bring something to hang any credibility in this on for normal long-term road use beyond immediate impressions?

[arek]

ratchethack, you are right. I did not approach this scientifically, and I did not control all variants to isolate it to the coating, so it is difficult to make this claim a fact. When the heads were off everything got cleaned, and brought back to stock. However, the engine had only 5k miles at the time, so it was not a 50k mile carbon build-up that was removed. It was fairly clean. Nothing else was changed.

 

The pinning was really bad. My road test procedure was opening throttle under load - 3rd and 4th gear going on a slight incline - at 3-5k RPM the thing was rattling like crazy - coins in a metal jar type sound ... first time I head it, it freaked me out and I posted about it here, because I did not know what it was. Repeating this same road test after coating the pistons, I cannot detect any pinning at all. I mean no pinning at all ... not "significantly less pinning." When you say that there is evidence of such coating performing on turbo and nitrous engines, but that this does not translate to a stock road engine of a Guzzi, I would have to disagree. To my mind this is completely reverse - if something works on an engine that is pushed to its limits, it will certainly work on an engine that is very conservative. However, something that works on a conservative engine may very well break down when pushed to the max ... durability and longevity may be another issue, and I will certainly monitor what happens over time.

 

I got the pistons coated at Polydyn . I coated both tops and skirts, with their appropriate coatings - $70 for pair. I did not take pic I don't know details about the process they use, only what I read from their website and what I could find on the web - basically nothing scientific. What I did like from their description of the piston coating, is that they formulate their coating to match the expansion coefficient of the substrate material, which made me feel better about cracking and pealing. Also, heat distribution may be the key here for helping with pinning. But again, no scientific proof, simply claims, which, however, so far seem to be working.

[GuzziMoto]

Coated piston crowns have been increasingly popular with forced induction and nitrous engine builders for years. Many of 'em swear by the heat reduction benefits to pistons, as evidenced by reduced discoloration of new pistons underneath compared to non-coated new pistons. The theory seems to be that non-transfer of heat into pistons is converted into usable energy output in the combustion chamber. Of course these motors are typically torn down for complete rebuild after a handful of passes thru the traps at the strip -- That's a useful operational life of miles in the low single digits.

 

As for benefits for a previously pre-igniting or detonating motor for the road??

 

This is just me, but seems more'n a tad far-fetched. A newly de-carbonized combustion chamber after heads-off work can be expected to ping significantly less than before, without any coating. A good hard anodizing accomplishes the same thing as ceramic coatings. Unlike coatings, hard anodizing can't flake off, and every quality piston made is already hard anodized.

 

I'm open-minded enough to reserve judgment pending credible long-term study analysis on the road over many tens of thousands of miles -- of which there doesn't seem to be any, as far as I can tell.

 

Somebody please bring something to hang any credibility in this on for normal long-term road use beyond immediate impressions?

I have a bit of experience with ceramic coating parts. Coating the top of the piston is a good thing and it could reduce pinging if you have a hotspot developing on the piston causing the detonation. Did you coat just the piston crown or did you do the combustion chambers in the heads as well? I see you did the crowns and skirts. In my experience the crown coating will last a long time and the skirt coating will wear off. But they may have improved the skirt coatings since I used them last.

Anodizing is a different can of worms entirely and has much less insulation value. Ceramic coating slows the transfer of heat into the part it is applied to. The part will still heat up but it takes longer and the final temp will be lower. If Hack does not see the benefit of a cooler piston in regard to detonation, well let's just say I am not surprised. ANYTHING you do that lowers the temp in the combustion chamber is likely to have a positive effect on detonation and performance. Good on you for doing what you did.

[Guest ratchethack]

. . . simply claims, which, however, so far seem to be working.

Arek, "so far"^ would seem to be the key that you're missing here.

 

I did not state , ". . .this does not translate to a stock road engine of a Guzzi". Nor am I doubting the accuracy of your observations.

 

Again, what I pointed out is that simply decarbonizing heads in itself typically yields the same results -- at first.

 

Speaking from my own experience, I've had the same reduction in pinging on many motors after decarbonizing the head(s) -- without any coating on the piston crowns a-tall.

 

I also pointed out that the popular trend in recent years with piston crown coatings is its application in race motors built for the most part to be completely rebuilt on very short operating cycles.

 

What works best on the drag strip in forced-induction and nitrous motors does not necessarily translate into the same long-term benefits on the road.

 

That's all.

[arek]

Arek, "so far"^ would seem to be the key that you're missing here.

 

I did not state , ". . .this does not translate to a stock road engine of a Guzzi". Nor am I doubting the accuracy of your observations.

 

Again, what I pointed out is that simply decarbonizing heads in itself typically yields the same results -- at first.

 

Speaking from my own experience, I've had the same reduction in pinging on many motors after decarbonizing the head(s) -- without any coating on the piston crowns a-tall.

 

I also pointed out that the popular trend in recent years with piston crown coatings is its application in race motors built for the most part to be completely rebuilt on very short operating cycles.

 

What works best on the drag strip in forced-induction and nitrous motors does not necessarily translate into the same long-term benefits on the road.

 

That's all.

 

I agree with you It is too early to make statements, so let's see if this hold up over time.

 

But, wouldn't it be great if it did tho ... a cheap and simple solution to a long fought problem I am optimistic ...

[Dan M]

This is interesting. A ceramic coating will insulate the piston crown from combustion temps but not reduce combustion temps. As GM indicated if there is a hot spot on the crown, ceramic may help but more likely the hot item that is igniting the mix is (was) red hot carbon. The coating may be hard and smooth enough to reduce carbon build up and help some over time. It would be good to know if the pistons are "clean" after a several thousand miles. We discussed this at some length a year ago (link below). I feel that the typical V11 that is prone to knocking does it for more than one reason, usually runs too rich at idle building carbon and too lean in the problem area (hmm, that 3000/5000RPM slight throttle problem area again.--- don't worry, I won't say the T word) causing combustion temps that are too high and heating the carbon to the point of igniting the mix.

 

 

http://www.v11lemans.com/forums/index.php?...=13981&st=0

[arek]

This is interesting. A ceramic coating will insulate the piston crown from combustion temps but not reduce combustion temps. As GM indicated if there is a hot spot on the crown, ceramic may help but more likely the hot item that is igniting the mix is (was) red hot carbon. The coating may be hard and smooth enough to reduce carbon build up and help some over time. It would be good to know if the pistons are "clean" after a several thousand miles. We discussed this at some length a year ago (link below). I feel that the typical V11 that is prone to knocking does it for more than one reason, usually runs too rich at idle building carbon and too lean in the problem area (hmm, that 3000/5000RPM slight throttle problem area again.--- don't worry I won't say the T word) causing combustion temps that are too high and heating the carbon to the point of igniting the mix.

 

 

http://www.v11lemans.com/forums/index.php?...=13981&st=0

 

It just so happens that I work for a company that makes world's smallest fisheye lenses, and I have a demo laparoscope with wide-angle lens on it (It has never been used ) It has input for light illumination and a viewfinder, so I will try to take few snapshots through the spark hole now - about 500 miles on coated pistons - and another after few 1000s of miles to see if, in fact, the coating is preventing carbon build up. This will also tell us if peeling is occurring ... for the skeptics.

[Dan M]

It just so happens that I work for a company that makes world's smallest fisheye lenses, and I have a demo laparoscope with wide-angle lens on it (It has never been used ) It has input for light illumination and a viewfinder, so I will try to take few snapshots through the spark hole now - about 500 miles on coated pistons - and another after few 1000s of miles to see if, in fact, the coating is preventing carbon build up. This will also tell us if peeling is occurring ... for the skeptics.

 

cool...

[Guest ratchethack]

. . .I have a demo laparoscope with wide-angle lens on it (It has never been used ) It has input for light illumination and a viewfinder, so I will try to take few snapshots through the spark hole. . .

OUTSTANDING, Arek. What a great tool. This is just me, but considering that a V11 motor takes every bit of 10K miles to generally break in, and will continue to loosen up as it seats new rings on the factory cross-hatch cylinder hone up to somewhere around 20K miles, I'd consider it a worthwhile method of decreasing ping if it still seemed to be effective after 20K miles. Depending on how ridden of course, I'd expect a simple de-carbonizing of the heads to go at least that far. Seems to me that for most road-going purposes, if any knock-preventive measure can't make it through the period of a complete break-in before the heads have come off for a re-do. . . well, then it's no better than a clean-up of the heads. In that case, it would seem to be a bit of a useless band-aid, wouldn't it?

 

Will look forward to your photo's.

[GuzziMoto]

Well, personally... seeing as your bike was pinging with 5k miles on it, if your bike puts another 5k miles on it with out pinging again and no signs of coating degradation (I doubt there will be as ceramic coating is tough stuff) I would say it is a valid option.

As for insulating the piston and/or the combustion chamber with the coating not reducing combustion temps, that would likely be true. It should slightly raise the combustion temp as the piston would be absorbing less heat. But what it should reduce is the combustion chamber temps right before combustion takes place. That is where detonation happens and lowering those temps can reduce detonation. It is not after the the charge is burnt that detonation happens but right before and during combustion (in the parts that have not combusted yet). Preventing the piston from absorbing some of the heat from combustion and passing it along to the next charge as it is compressed can and will reduce the temp of the mixture and thus help reduce the chances of detonation.

[Guest ratchethack]

Say Arek

 

Weren't you the guy with the mysterious oil-in-the-cylinder-head thing about a year back? Did I refer you to Mark Etheridge at MG Classics in Signal Hill? If so, did you have Mark do the work and/or take the heads to their local machine shop go-to guys?

 

I can see how such a thing could easily carbon up your heads at 5K miles.

 

How did that little excursion go, and what was determined to be the cause?

 

Enquiring minds. . . (well, you know). . .

[arek]

Say Arek

 

Weren't you the guy with the mysterious oil-in-the-cylinder-head thing about a year back? Did I refer you to Mark Etheridge at MG Classics in Signal Hill? If so, did you have Mark do the work and/or take the heads to their local machine shop go-to guys?

 

I can see how such a thing could easily carbon up your heads at 5K miles.

 

How did that little excursion go, and what was determined to be the cause?

 

Enquiring minds. . . (well, you know). . .

 

Yeah, and no, I did not go to Mark, but rather I sent the heads to Mike Rich. Originally, I had a shop in SoCal - the name of which I probably should not mention - simply clean the heads and valves and put it back together, but they did such a poor job - 3 times I shipped the heads back and forth with problems - and I finally shipped them to Mike. The oil seeping through the guides was result of their work, and not a problem I tried to fix. When they arrived at Mike's, he had to re-seat the valves seats, install new guides.