Weird cylinder scoring?!

jcovey2.5

jcovey2.5

New member
Posted this on Nasioc but i wanted to ask you guys too.

This is my 04 STi motor at Lobstah's, with wisco forged pistons, stock size, with cobb rods.

Anyone have any idea what would cause this scoring on the cylinders walls??? Its like this on all 4, top and bottom of the walls...

The spacing on the pistons are off too. My guess is they are rubbing on one side of the wall on the way up, and against the other side on the way down...

Anyone have any input on this???

Thank you in advance!

Joe

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wow, I got off the phone with Lobstah. Seeing the pics its worse than I thought. Who built your motor? Did you do a rehone and fitmit before droping in those pistons? Also Holy crap balls on the build up on top of the pistons.

 
ECS did it under 2 years ago, not sure of how they did the install... im calling them today though

haha ya there is a whole lota carbon build up. its because i was running so rich for the past year and a half, which is probably because of the gaping between the pistons and the cylinder. the ecu was probably dumping more fuel in to try and compensate...

but ya rehone and oversized pistons are probably next. or sleeved what ever will make me more power in the end

 
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the cylinder honing itself was perfect. The scoring wasnt - a fingernail was fetching up on some of the worst gouges.

 
those motors come with a A and a B piston

which one piston is bigger than the other piston

which if you put the pistons in the wrong spots i'm sure this could probably happen

but i am only guessing chalk another one up to ecs

 
those motors come with a A and a B pistonwhich one piston is bigger than the other piston

which if you put the pistons in the wrong spots i'm sure this could probably happen

but i am only guessing chalk another one up to ecs
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But there are no A/B sized aftermarket pistons that I"m aware of, so if you use stock bore you're bound to have some inconsistency. Personally if I were to ever have an engine built I would just spend the few extra and have it bored to either 99.75 or 100mm to ensure you're getting proper and consistent p/w clearances.

 
someone made a good point over on NASIOC:

"Looks normal for 2 years of forged piston slapping. Hell, my CPs prolly look worse and I put mine in a little less than 2 years ago.

Remember, forged pistons are fit loose because the _expand_ people. They are going to tear up the walls and the car will eat a tad more oil."

I let the car reach temp as much as i could before driving, but by the looks of it its never enough...

 
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ECS did it under 2 years ago, not sure of how they did the install... im calling them today thoughhaha ya there is a whole lota carbon build up. its because i was running so rich for the past year and a half, which is probably because of the gaping between the pistons and the cylinder. the ecu was probably dumping more fuel in to try and compensate...

but ya rehone and oversized pistons are probably next. or sleeved what ever will make me more power in the end
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Just a heads up whatever you do. Do not sleeve the block. You will make some nice power but you will be rebuilding your motor in no time at all. This is well documented over on iwsti.com For whatever reason the EJ257 doesn't liked to be sleeved. Number of people have done this and most have failed. Just a warning.

I just spoke with Lobstah again this morning. If I were you. I would get him to tear the engine down. Take it to a machine shop have them bore it out. Maybe to 100mm from 99.5 (stock) then rehone. Next buy some CP 100mm over pistons and slap back into it.

You can tell just by looking at the motor that when they did a rebuild on your motor they didn't take it all the way down and do a rehone on it, or whoever did it did a craptastic job of it.

Tearing a EJ25 down is a pain in the ass so I have been told by EFI Logics. I have been checking around for a motor rebuild. They pretty much told me you are darn near better off starting with a brand new oem shortblock then slapping performance pistons in. I know for them just to crack the block and rehone it I am looking at another $1k in labor. So for another $800 I could just have a new short block then take out the stock sti pistons and sell them then slap in some aftermarkets.

Up to you man. I am just giving my 2 cents because I have done extensive research on all of this just because I am looking into a motor rebuild or possable new block with CP pistons.

Good luck with everything man. I will check up on your post here.

 
someone made a good point over on NASIOC:
"Looks normal for 2 years of forged piston slapping. Hell, my CPs prolly look worse and I put mine in a little less than 2 years ago.

Remember, forged pistons are fit loose because the _expand_ people. They are going to tear up the walls and the car will eat a tad more oil."

I let the car reach temp as much as i could before driving, but by the looks of it its never enough...
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Do yourself a favor and leave Nasioc alone. If you want good expert advice from tuner shops and people in the biz in general go over to iwsti.com you will get better input and and be flamed for asking a possible dumb question like on nascrap. You shouldnt be able to feel much less see cylinder wall scoring like that. Plus, from just looking at your pics and talking to Sergei you can tell oil was cokeing ontop of your cylinder. Looks like someone dumped oil down your cylinder on top of the pistons and then took a blow torch to it and baked it on. I was telling sergei you could try to clean those pistons up just as long as the scoring did "josh" up the piston itself. Hopefully you just need new rings. Problem is you are going to almost 100% need a bore on the cylinder wall to fix that.

No piston slap is not normal. If you have piston slap means you had someone build your motor that doesn't know what the hell they are doing. Or they didnt bore or hone the cylinder properly.

Just head on over to iwsti.com start reading up on things you will learn a lot.

 
Well I looked into everything and checked receipts with Paul at ECS. Turns out they didnt mess up at all...he was actually really helpful and knowledgeable.

The scoring might of been caused by bad oil pressure causing the rings to score the walls.

So im going to bore the cylinders and go with 100mm wiesco pistons. anyone know a good shop?

 
my well-informed theory is that the scoring is due to an evil combo-- modded engine, lots o' boost and a heavy right foot

funny how that combo tends to blow stuff up

don't axe How I Know......
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Jcovey get ahold of the guys at M&A. They have a local shop they swear by for there work. I let Sergei know about this also. I would let them bore the cylinders first then buy the pistons. Depending on how bad the scoring is they might have to go over 100mm for the bore sizing. You might have to go up to 101 mm's. Just let them know your intentions before hand so they will know you want to go either 100mm if you can or if they have to go over go to a size that you can procur easley.

Good luck man.

 
i got shop literally mile from me that's been doing vw bettles forever. I am bringing my sti block to next week to have bored and honed to 100mm but you need the pistons first to make sure the machine shop you do choose makes the correct clearance for the rings and pistons.

 
i got shop literally mile from me that's been doing vw bettles forever. I am bringing my sti block to next week to have bored and honed to 100mm but you need the pistons first to make sure the machine shop you do choose makes the correct clearance for the rings and pistons.
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Whats the name of the place? Phone number?
 
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