Piston ringland damage

[500orbust]

Has anyone seen this type of damage before? This is a ross stroker piston for an evo 8.

 

[97 4G63]

Nope ..
But you need a new piston.
That almost looks like a new piston what happened??

 

[bluegs03]

wow that almost looks like it was machined wrong or something??

 

[500orbust]

This happened to all 4 pistons. Machinist / engine builder thinks that its most likely from not letting the engine warm up fully before driving hard. There are no signs of detonation on piston, head, spark plug, or rod bearing. This isn't from my engine...thank god. Just trying to get some opinions.

 

[donniekak]

Looks like maybe they had off set pins and were installed backwards. Any scuffing on the skirts? Also running the engine hard before it warms up can have the rings rattling in the grooves because everything isn't heated up evenly.

 

[sb7775]

Looks like maybe they had off set pins and were installed backwards. Any scuffing on the skirts? Also running the engine hard before it warms up can have the rings rattling in the grooves because everything isn't heated up evenly.

This is what probably happened. Could you check the damage on all four and let us know if the damage is in the same place on all 4. What rings were use and what did they look like?

Steveb

 

[500orbust]

The damage was only on one piston. I rebuilt it with wiseco's and so far no problems as of yet...There has been at least 7500 miles on the new rebuild.

Ross pistons staff were also surprised to see the piston damage. They have not seen anything like this before, and do not have any ideas of what caused it.

archie

 

[donniekak]

The earlier post said all 4, hence my diagnosis. If it only happened to 1 i would say that one part of the ring groove was wider than the other and the ring vibrated back and forth grinding away the aluminun. Bad machine work on the piston.

 

[500orbust]

The earlier post said all 4, hence my diagnosis. If it only happened to 1 i would say that one part of the ring groove was wider than the other and the ring vibrated back and forth grinding away the aluminun. Bad machine work on the piston.

Sorry, I meant that the damage was this bad on only one piston. The other 3 were not this bad, but still showed damage.

 

[brassc2007]

posibility is that the rings were not gapped right and the ring was slightly binding when warmed up causes the piston to flatten out in that spot but usually if the rings bind it breaks the lands right off the piston

 

[toofast82]

This happened to all 4 pistons. Machinist / engine builder thinks that its most likely from not letting the engine warm up fully before driving hard.

I've never seen that before!
I'm not buying what the machinist said. I see cars running at the track all the time that aren't at operating temperature. That will usually cause the cylinders to scratch and cause blowby i believe.

To me it sounds like a machining/wrong part error. First clue is it happened in all 4cylinders. Second is its a stroker which could have wrong crank/pistons. Did you double check to be sure they were in fact stroker pistons/correct crank? Did your friend order the parts, or machine shop?

You're the guy that ran on PassTime, right? How is your car holding up?
I remember you were running 30psi+ on 7bolt bottem end.

 

[99gst_racer]

What were the rings gapped at and how much boost?
How did the cylinder walls look?

 

[blackGSX2g]

I'm not buying what the machinist said. I see cars running at the track all the time that aren't at operating temperature. That will usually cause the cylinders to scratch and cause blowby i believe.

The cars you see running at the track are probably running warmer than you think. Plus thats a far cry from firing up a stone cold engine in 30-40* weather and giving it WOT.

JE's are well known to have more piston slap during warm-up than other piston manufacturers which is why I chose Wisecos, but I''ve never seen that before. Worst I've seen is egging from piston slap.

 

[Big Woo]

I have seen this before it is from incorrectly gapped piston rings. In a nut shell the piston ring end gap was too tight, and the thermal expansion of the rings caused the pistons to deform.

This is an assembly problem.

 

[toofast82]

The cars you see running at the track are probably running warmer than you think. Plus thats a far cry from firing up a stone cold engine in 30-40* weather and giving it WOT.

The cars at the track with high compression aren't letting their cars sit there and idle to operating temp though. They may be at the stage at 130* or something like that. Not ice cold but not op temp.

If someone is at wot stone cold in 30-40*, they deserve for their pistons to look like that.

BigWoo explained it pretty well, which may possibly be the cause in the post above

 

[TOONAH]

I agree that the photo shows that material was 'removed' from the lower land area. It was not compressed or deformed by too small ring gap. That kind of damage shows stress and deformation to the piston alloy. I agree that somehow, the ring itself 'machined', the alloy away. Was there silver flakes in your oil pan? I too have never seen that before. I always idle my engine to operating temperature before doing any fancy driving.
My best guess is that the ring may have had proper ring gap but the land itself was cut too shallow during the manufacturing process.
Get the specs on ring land depth and measure the land depth on your pistons.

 

[Big Woo]

"Yes it is always best to assume that the manufacturer had a quality problem"

Continue on with ignoring the real issues at hand and the problems will also continue.

The picture provided shows the back of the ring land quite well, and one can see that the depth is stepped deeper where the manufactured groove is, and shallower where the deformation/machining/whatever you want to call it occured. Also the back of the ring lands look (from the provided picture, and at the manufactured grooves depth) good i.e. no galling or evidence of metal to metal or ring to piston contact.

The last time I checked thermal expansion caused things to well "expand"WTF

By the way did you happen to be using a "gapless" top ring?