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[snm95ls]

Built an LS-VTEC last year for a friend.  We pulled the head to replace it with a ported one.  The cylinders seem to have some pretty significant scoring on the intake side of the sleeve.  It kind of worries me as you can feel them pretty easily and this thing has only 10K miles on it so far..  The engine does not seem to have any oil consumption issues.  When it was brand new it laid down 184 and 127 which surprised the hell out of me.  It did dyno later significantly lower at like 175.

I know it has been run hard many many times since it was built.  It has been run hard when it was very hot, I guess he was getting into the red with coolant temps.

Just seems kind of odd since it is only on the intake side of the sleeve and not really all of the way don the cylinder.  It almost seems like it is at the point where there is possible the greatest side loading on the cylinder.

Any ideas what could have caused this? 

EDIT:  I don't have pics right now, but the scoring looks very similar to the pic below minus the orientation.  In this pic it is inline with the wrist pin with is about 90° off from what I am seeing on this engine.  Like I said, right on the intake side, and the scroing looks pretty much like that.

[ApexSilver06MR]

ouch!

[snm95ls]

ouch!

Kind of what I was thinking.   

I would kind of like some insight into what may have gone wrong.

[Dweezil]

Just a guess:

To much heat from being lean and the piston over expanded and scored the wall. Either that or a busted ring.

[snm95ls]

Just a guess:

To much heat from being lean and the piston over expanded and scored the wall. Either that or a busted ring.

I would think that it would be on both sides though, not just the major thrust axis, intake, side.

As for a broken ring, all of the cylinders are scored on the same side of the sleeve.

ARG!!!!

I am leaning more towards fuel wash, but the fact that I know it has been run hard when the engine was very hot makes me a little unsure.

[Dweezil]

Pull the pistons and see what's left. Should be able to tell pretty quickly that way.

[snm95ls]

Pull the pistons and see what's left. Should be able to tell pretty quickly that way.

True enough.  I kind of don't want to though.

Lol.

Kind of want to know if or what I may have done wrong so iI don't do it again.

 

[snm95ls]

Just ran across this:

http://www.mlcmotorfactors.co.uk/Trouble%20Tracers/PistonTT.pdf

Pretty neat little guide.

The one that seems to fit what I have seen on this engine so far points to oil dilution either by fuel or oil.    Also mentions the lack of oil spray form the connecting rods.  LS rods have these and the ACL bearings are not drilled for them  I am going to make a fixture to remedy that issue on a current build.

It was probably oil dilution during the initial start up.  The friend that I built the engine for forgot the o ring between the MAP sensor and the throttle body, so I had a hell of a time getting fuel trim adjusted until I figure it out.  My datalogging setup was not working that day.  I wonder if the pistons are fine, and just the rings and bores are fuckered.  They were coated.  I doubt it though.  Fuck me.

I guess there is the slight possibility of a combination effect of overheated cylinder walls and a lack of the oil squirters.  I doubt it though.

Fuck.

 

I wonder if the aftermarket LS and D series rods have the oiling holes.  Never laid hands on them, so I have no idea.

[Dweezil]

Looks like you found your answer there. I'd trust FM over most of the internet seeing how they make pistons.

[snm95ls]

Looks like you found your answer there. I'd trust FM over most of the internet seeing how they make pistons.

Exactly.

The link might make a good sticky.

 

[Dweezil]

It is on MichiganCivics now, but it should be here.

[d-rail]

MY GOD MAN!!!!!! What the hell happened there. I can't see their being that much of a lean condition without melting a piston. Not sure of wash out though. That's something I've never seen before but it looks rougher than your mothers anus.