what would cause all four pistons to crack in the same spot? they are wiesco.
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each piston is cracked in 2 spots, all four in the same spot.

 

A little history on the setup and what was going on when it blew would help a little. Almost looks like the piston skirt is hitting a lip on the bottom of the sleeve. Was it a sleeved block? Any machine work done?

 

y8 block, stock sleeves, eagle rods. the ringlands on one of the pistons were broke for a long time, had bad scaring on that cylinder wall, and some of the piston was missing behind the valve relief. still drove it for about 6 months after i discovered this. people said when they were behind me they could see hot ambers comeing out of the exhaust. finally one day on the e-way, lost all compression on that cylinder. fast forward to today...took the head off, the intake valve on that cylinder had a peice missing, along with all the piston damage. who knows how long it was this bad.

 

looks to me like it was possibly overheated? if you drove it around for months after you knew it had a problem, im guessing you probably beat on it pretty hard?

 

what did you use to tune with

what was the compression?

You probably running too much timing

 

I've never seen pistons crack at the skirt like that

Maybe I haven't seen enough blown motors, but damn.

 

i trashed this motor. ran the vafc hack for awhile, then converted to a p28 and used beer bongs bin. never got it tuned properly. blown numerous headgaskets, and drove with it that way alot.
funny thing is it was pretty quick, would beat evo's and srt4's on a regular basis.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2redstars &raquo;</TD></TR><TR><TD CLASS="quote">i trashed this motor. ran the vafc hack for awhile, then converted to a p28 and used beer bongs bin. never got it tuned properly. blown numerous headgaskets, and drove with it that way alot.
funny thing is it was pretty quick, would beat evo's and srt4's on a regular basis.</TD></TR></TABLE>

well its your own fault and i believe you just answered your own question.

 

at least it shows where the weak spot for those pistons at : / .......

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oleg &raquo;</TD></TR><TR><TD CLASS="quote">at least it shows where the weak spot for those pistons at : / .......</TD></TR></TABLE>


No, it just shows how much of a retard he is. That's all.

 

Well lets assume for a second that the tune didn't do it. That there wasn't massive detonation. That there wasn't tons of unburnt fuel in the exhaust being lit because the timing was way retarded. If the block was milled much at all, the HG was run as a 2 layer, and pistons were for a z6, you probably had some bit of piston/head contact. Normally I'd guess that it would grind the bearing into the crank, but maybe you had great oil pressure. You should have seen cranked ringlands before this if it was detonation. SO it leads me to believe that it was some odd sort of contact.

I would try contacting Wiseco (seek answers before a refund, they'll be more helpful), maybe they had a bad run at one point, maybe they redesigned it. I know that with a decked y8 block, 2 layer OEM HG, and z6 pistons, the piston deck height would have been enough to stick out past the HG and touch the quench pads on the y8 head.

 

post a pic of the tops

 

How high were you revin' when this happened? Was the piice of the intake valve burnt away or was it broken and gone?? High revin and the valve broken would seemingly explain that part of the story as valve-piston contact. What size are the pistons and do you trust the machine shop that did the bore/hone? You ran your car numerous times with a blown hg. By doing so you are just asking for thermal stress issues. If I HAD to make a guess right now, I would say 95% poor judgement and the other 5%........poor judgement.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by F20Cteg &raquo;</TD></TR><TR><TD CLASS="quote">No, it just shows how much of a retard he is. That's all.</TD></TR></TABLE>

Well, from how he is talkin about it he doesnt seem that worried or pissed off. He is just asking the question.......but with all the problems it had before the total loss of comp and he still ran it that way for ~six months shows me he doesn't really care about his engine. I would presume that he is really not all worried about it. If he isn't why should we be??

ps - I don't know wiseco's return policy, but I doubt they would refund/exhange the pistons. I wouldn't. GL.

 

yeah, im totally not pissed or anything. i knew this was going on and just ran it into the ground. it just seems wierd that all four were cracked in the same spots. rev limiter was at 7300. and i was just cruiseing on the eway and got off at an exit and as i slowed down i could tell at least one cylinder was gone. i will post more pics in a little bit.

 

pics of the tops and broke valve

 

omg.. ouch.. you beat those to hell.

this should have a graphic content warning.

 

any other theories on why they all cracked like that? could it be a defect? besides the the piston damage and broke valve, there was some scaring on the upper part of one of the cylinder walls, the rods look fine, and the crank is fine.

 

was the crack on the intake or exhaust side of the piston?

 

That's pretty damn funny really. There's any number of things that could have been wrong. Regardless, you didn't care about this one before, so don't start now. Build your next motor right and get it tuned and you won't have to play "what caused this?".

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">That's pretty damn funny really. There's any number of things that could have been wrong. Regardless, you didn't care about this one before, so don't start now. Build your next motor right and get it tuned and you won't have to play "what caused this?". </TD></TR></TABLE>

True. If you choose to reuse your rods have them inspected as well as the crankshaft for straightness. Also look inside the bottom of the block and look for any signs of contact. It almost looks like the counter weights of the crankshaft hit the sideskirts of the pistons due to the uniform damage. But other than that... I don't think the detonation helped out matters.

 

Yeap people still amaze me..............Good luck on the next one maybe it will last FOREVER