Swain Tech coatings

[FestYboy]

yeah when i saw the pix and where the wear was, i thought to myself "fuel errosion". I'd call up Swain and see if they've done any E85 testing..... and request a fix.

[gauge_half_inch]

Well that's the thing, this engine hasn't seen E85. I leaned out with the old worn out engine. I haven't even tried it with this one.

[blkfordsedan]

It would be very interesting to see what they have to say....will they admit to a quality or material failure or blame it on bad tuning, etc.? Have you thought about finding a B6t block with oil squirters? I wish I knew more about forced induction. Please keep this thread updated!

Also, since your head is off, any chance you can drop a dial indicator on it and measure the cam lobe lift? I'm curious to see if our "FMS Street" cams are the same.

[FestYboy]

Dennis, what i was getting at was that IF they did E85 testing, they could rule out the possibility of fuel errosion being that you're only using E10 (or less). if they havn't done any such testing, i would then conclude that the ethenol in the fuel is doing the damage and they coudn't say otherwise.

[Hot_Wheels]

Are the injectors sticking? Do you have a afr gauge? I want to send my pistons out but if its just going to wash away i wont waste my money

[gauge_half_inch]

I'm using an safc2 and afpr for tuning. Cold start its off the gauge rich with the pressure needed for top end with boosts raising the pressure. After a few mins the afrs drop back down into the 15 range. Cursing I have it a little lean for economy at high 15 low 16, as soon as boost sets in using a map sensor to trigger the safc to switch maps. Under boost my afrs are low 13 high 12. I read through swaintechs site very carefully before placing my order. There was nothing written about fuel or forced induction/ naturally aspirated. I'm really curious about the skirt coating, but didn't have the time to pull out the pistons yet. If the skirt coating is anything put perfect they will be reciving an email with detailed pics. Simply put, at this point their services quality effected the integrity of my build.

[Hot_Wheels]

regardless of the side skirts i would still send Swaintech the pictures, im sure the pistons tell the story. Its like reading spark plugs. I would suggest posting it on miataturbo.net as well just to get there opinion on what may have caused that. On the plus side i dont see any signs of detonation so the coating may have helped prevent that, but maybe the excess heat was directed to the rings causing them to fail? I know you said the 2 center pistons where 70 and 90, what where the other 2? how does the top of the head look?

[gauge_half_inch]

Yes the test went dry #1 172 #2 90 #3 70 #4 158, wet #1 180 #2 175 #3 185 #4 158. The head probably needs re worked as #4 had no change, but it has over 200k in touched. What exactly about the head is it your asking about.

[Hot_Wheels]

if there is any detonation marks.

[gauge_half_inch]

Not that I could see. The head looked great.

[mattdickmeyer]

gauge_half_inch.....Part of our engine development program involves reverse engineering damage to find the cause so as to not repeat destructive events. What has happened here is clearly evident & I can explain to you what happened. You have several issues, that when combined, caused your problem. You're running a B6 turbo charged with ceramic coated pistons. First of all, the B3 & B6 port configuration promotes high level of swirl. Combine this with induction pressure "boost" causes fuel separation as the charge rolls over the back side of the valve & causes fuel puddling ear the exhaust valve. This is evident by the picture of your piston. The lean condition occurs at the intake valve & the fuel rolls around the cylinder in a clock wise or counter clock wise direction, depending on cylinder position. This washes the oil from the cylinder (especially on a glazed worn cylinder wall or fresh engine with incorrect honing for oil retention) this scuffs the ring causing cylinder leakage (blow by) any oil introduced into the combustion chamber propagates detonation. The ceramic coating applied to your piston tops is a thermal barrier meant to retain heat in the combustion chamber further compounding your problem. Remember this is a ceramic "coating", if the coating can be applied it can also be removed. for this application hard anodizing would have been a better choice as this process becomes a part of the piston surface. Finally your tune is way off. In a perfect world with the ability of infinite tuning a N/A engine is targeted for 12.5-1 AFR to the RPM with peak torque then leaning out to around 13.0-1 at wide open throttle. Any engine with forced induction is targeted to 11.5-1 up to peak torque & then slightly leaning out to around 11.7. Of course all engines like a slightly different tune but in your instance slightly richer would have had a cooling effect on combustion temps. From what you have said your tune was slightly lean even for an N/A application. To summarize you have a cylinder head that promotes fuel separation added boost which requires more fuel, more fuel separates easier, fuel separation runs ring seal allowing oil in the chamber, boost adds combustion temps, the ceramic coating retains combustion temp in the chamber, add a lean tune to this & it is evident the edge of the valve & sharp edge of the intake VR retained heat & worked like a glow plug, detonation occurred in this leanest area & blasted the coating off the piston top.

[Hot_Wheels]

See i knew there was a way to read this! Maybe this is why wiseco only coates the side skirts and not the tops? But then again i think the flyin.miata pistons have coated tops?

[mattdickmeyer]

Most pistons come with no coatings or skirt coating only for 2 reasons. 1.) Any one buying a "shelf" piston, there application most likely does not require the specific use of coatings. 2.) Simple economics. The application can of specific coatings can easily double the cost of a "shelf" piston making a $500 set of 4 pistons become $1,000. The use of coatings in custom pistons is widely used. For example, we use skirt coatings on virtually all of our pistons. A particular advantage on stroker engines where long stroke crank shafts generate greater friction on cylinder walls. Coated skirts also require less oil allowing the use of thinner low tension rings, which offer a significant HP advantage. Ceramic piston crown coatings are typically used in high HP N/A engines to control combustion temperatures within the chamber. In moderately boosted engines this also helps retain exhaust heat & energy which has a positive effect on turbo response but requires precise tuning. Hard anodizing is used generally in high HP boosted engines. This hard surface protects skirt wear when using softer 2618 forgings which is stronger (in terms of shock tolerance) than a 4032 forging. Hard anodizing is also used on piston crowns as well on these applications. This process offers brief seconds of protection during spontaneous detonation. It also reduces piston ring micro welding in the ring lands as cylinder pressure can distort the piston crown & pinch the ring. Micro welding will cause the piston rings to stop rotating which will cause immediate damage.

[gauge_half_inch]

Thank you Matt for your input. Any suggestions on how to fix the issues, or lessen the effects? I have larger injectors I can instal, but haven't. For the record I have been fairly gentle to this engine knowing I'm running a littke lean. I have priced wiesco pistons for the b6t and plan to have them fly cut to match the valve releifes to stay non interference.

[mattdickmeyer]

I most certainly would not go that route. Making a piston work for the wrong application is crude at best. I am building forged B3/B6 pistons as we speak tho I have pushed that aside to work on a set for a BP that I am doing. I would be more than willing to provide you with a set of correct pistons for your application. You also need to open up the combustion chamber not for the purpose of reducing your C/R ratio but to reduce mid range swirl & increase overall flow which will help fuel atomization. Feel free to call me at the shop (260-723-4584). I would be more than willing to help you make your build successful.