Piston pic.
 

Since my last thread went so smoothly :D Figured I`d ask another dumb question since I`m always trying to learn, (don`t know much about bottom end stuff)
Just wondering if this is normal for the piston to be so nasty near the exhaust valve but looking good everywhere else. ??


http://33outlaw.zenfolio.com/img/s1/...71068997-3.jpg


http://33outlaw.zenfolio.com/img/s3/...77851334-3.jpg


Same piston.

Dan are all 16 like that one or are there only a few? only one engine with a few?

to me it looks like burnt oil deposits.the bottom picture looks like the second ring is a zero gap ring.edit in,also looks like the oil ring support rail is missing.can you move the oil ring pack up and down?

don't think they're gapless 2nds but I definitely don't see an oil support ring there... what's up with that???

hart to tell for sure by the pics

dan,don,t take the rings off.i want to look at that up close.

Second ring looks gapless to me

I think the what appears to be a gapless second ring, may be the top oil support rail. looks like it has been moved up to that spot upon removal of the piston, that gives the appearance that it is missing from the left side of the upper oil ring pack. my eyes are not as good as they once where

yes.after seeing it blown up i can see the oil ring support rail and yes it is a zero gap 2nd ring.

that really shows how hard it is to tell what is going on with pictures posted on oso.

seems most of them look like this (black)


.. the rings are all there...


http://33outlaw.zenfolio.com/img/s11...42601431-3.jpg

http://33outlaw.zenfolio.com/img/s11...54704728-3.jpg

Looks like a childs and Albert zero gap second ring

yes,the company is now childs&ackerly i believe

Yes they are couldn't see the step in the ring in previous pic.. also has the support rail for the oil ring too...
I use the stainless total seal gapless upper rings in mine but those are also great rings...

I totally understand gapless top ring - but since their conception (seemingly a few eons ago) I've never been able to wrap my little pea brain around any benefit (just negatives) to a gapless second ring. What am I missing for benefits or possible benefits of gapless second ?

Gapless second rings came from when the gapless tops started getting thinner, but they didn't have the material technology to stand up to the heat and abuse. They then started moving the gapless ring to #2 but since then, ring technology has come a long way the the gapless 2nd is a thing of the past. With a gapless 2nd, all the top ring does is protect the 2nd...it can't do much for compression.

Very typical to see that on the ex side of the piston. That's where all the heat is and where all the gasses concentrate on the ex stroke. Any un-burnt fuel and oil will accumulate there and get baked on the piston. Engine was sealed up nicely.

^^^^ that answers my question, thanx.
You can see there`s a bit of scuffing on the skirt, that is also on most pistons even on the "good" motor. Thoughts on that?

if you can,t feel the scuffing with your finger nail it is nothing to worry about.

Is that from piston slap?

New LSX supercharged COPO camaro engine has

Mahle .043" x .043" x3mm
Ductile iron top with radius molybdenum face
Plain cast-iron tapered 2nd
Chrome-plated oil rails with low-tension expander

GM 572ci 720R engine
Plasma Moly top rings (unsure if steel or ductile)

Ford Supercharged 5.4L
Plasma moly steel top ring Mahle

6.0L LS Corvette engine
Plasma moly steel top, iron second

Dodge Viper V10
Plasma Moly ductile top ring, iron second ring

6.4L Hemi
Plasma Moly steel top ring, iron second

Just doing some research. I don't believe mercury racing used gapless ring sets in their HP engines? Unless maybe on the new stuff like 1350s? Idk. Its interesting some of these new modern engines, are still using conventional rings, making more HP per ci than ever, thinner oils than ever, longer oil change intervals than ever, and so on.

Be careful with your research sources. A lot of terms and nomenclature gets regurgitated with no thought or verification of accuracy. I know Ford has been using steel (not moly, just steel) top rings for a LONG time on the 5.0 engines. I doubt very much any of those factory engines you mentioned are using Moly top rings. "Plasma moly" and "steel" usually don't go together in the same sentence when talking about rings. There a lot of coatings available for steel rings, but "plasma moly" isn't one of them AFAIK. I could be wrong and I'm going to do some checking, and if so I'll be glad to apologize...

2010 Ford Supercharged 5.4L

Plasma Moly Carbon Steel Top ring

Mahle part 42112CP

http://catalog.mahle-aftermarket.com...rId=784222&d=t

6.0 LS GM Engine

Plasma Moly Carbon Steel top ring

Mahle #41858CP

http://catalog.mahle-aftermarket.com...rId=615547&d=t


6.4L SRT Hemi engine

Mahle #42156CP

Plasma moly Carbon Steel top ring

http://catalog.mahle-aftermarket.com...Id=1206357&d=t







Isnt "MOLY" a coating on the face of the ring, and "plasma" the process used to apply the coating? I've always assumed a top ring is either Steel, or iron, with a "MOLY" coating applied to the face. Pretty sure OEM's have been using moly faced steel top rings for some time now.

Dan, if you were to use the piston rings JE suggests with those inverted dome 4.500 bore pistons, these would be them.

http://www.summitracing.com/parts/jep-j100f84500-5

http://www.jepistons.com/Products/257942.aspx

It was a oil containment issue(had to use that line) looks like may have been from valve guide/seal or possibly intake sucking oil.speaking of rings the trend now is a very low drag, and a very specific hone to match the rings, down side to this is oil control, that old balancing act. Also crankcase pressure can cause oil to be forced by the rings, several things to look at here...

i would not install a low tension ring in a endurance marine engine .

imo you can not go wrong with total seal ap rings.

Inline with the ring talk, What about the piston design Icededpple is using - meaning the 'antidetonation' or sometimes called 'contact reduction' grooves ?
I know what the manufactures say about them but it seams alot of prof builders don't say much at all about them.

Seen this for a bit in the 2 cycle world before 4 cycle apps. With 2 cycle, it supposedly holds more oil in those apps. Remember, oil is air or fuel fed.

Anybody have any info either way ?

I`d rather have a flat top personally, less chance/area for the flame front to go bad.

That's what a 1075sc does and I think its a great idea less area for the piston to absorb heat.

2 ways of looking at that,some say it,s more area to disipate heat.

Also going to help lifting the ring land by the intake valve. Almost no valve notch.

I think you are talking about a full dish, VS a D Shaped cup like icdedpple has? 1075 merc uses a full dish I wanna say, with the piston quite a way down in the hole too.

Aftermarket flat top pistons have a good sized valve notch usually.

Send the head to Diamond. They will make a piston with a dish that mirrors the combustion chamber. Tell them you want a 2degree slant towards the exhaust valve.

Flat top in a 1075sci in the hole a bunch if anyone wants the CH I will measure it.
[ATTACH=CONFIG]548444[/ATTACH]

Looks like a flat top from here! Thats a small valve relief for sure, compared to most shelf JE, CP, etc

Yep pretty flat around .125 ish deep valve notch just a guess. Mercury put a lot of R&D into it pretty stout around the notch.

i guess you don,t need a deep valve relief if the piston is far enough away from the valve.

Update from High Flow Heads.

1. Some of my valve stems are worn, most likely from contaminated oil (blowby) , some of them you can feel the edge with finger nail.
2. Good thing for aftermarket Iron heads, Aluminum would have been damaged from the amount of heat I had .
3. 1 Super alloy Ferrea valve is cracked and tuliped (cylinder with busted plug)
4. Need 11 exhaust valves and 8 intake.
5. (4) exhaust valves had to be tapped out.
6. Springs pressures same as new. (spring oilers helped?)
7. Valve train otherwise very stable with no other damage.
8. Top of valve contact path great @ .050 ( Thanx Joe)

All in all pretty lucky not to have more damage from a stuck valve.

Mike @ high Flow likes Flat top pistons .. his explanation was something to the effect of

I can`t swing new pistons so I`ll stick with what I have as along as they are still ok.