VaNDaL*SS*

iTrader: (1)

Well after pulling apart my motor to see just wtf was up on piston 7 with an 85% leak down test i came to find this
I was having p-v issuses on all 8 intake valves (they all looked just like this)

Here is what the major problem is and i cannot figure out just y it happened.




When we pulled out 7 and began to see what was broken, we did not notice to much. The rings were intact and no noticable cracks or breaks in the piston other than where the valve kissed the piston. So when we pulled the rings (which were completely intact) the 2nd ringland just fell apart in our hands...im stumped as to why it would break like this and not destroy the rings...my guess is this was a factory defect and when i pushed on it, it gave way, tell me what u guys think
-Ryan

wait4me

iTrader: (10)

piston to valve with that cam? Is the block and heads decked? I hate the stock pistons...

VaNDaL*SS*

iTrader: (1)

heads are milled ~.030 but i was advised that this setup would have no problems from MTI, turns out its the oppisite

MadBill

The pictures are all way too fuzzy to make out anything, but 'second ring land' failure (i.e., the land below the first ring) is often due to detonation. It pounds the top ring so hard that it in turn breaks its supporting land.
Re 'valve into piston': 1. Intake or exhaust? 2. How do the other 7 look re contact? 3. How's the spring tension on the valve that hit? 4. Any tuliping of the intake valves (i.e., look like they've softened and been pulled part way into the ports) 5. Are any of the rings shiny on the gap faces? 6. Any major discolouration/blackening of the undersides of the pistons?

superchannelkev

iTrader: (8)

sucks man.... we had our #2 piston shatter into pieces on a friends car.. sucks

white2001s10

iTrader: (4)

I thought ALL your model car that came with manual trans could have potential piston to valve contact.

From the picture it looks to me like it may have overheated at least on that cylinder... pic is fuzzy though. I'm sure the P/V contact had nothing to do with the piston failure in this case.

Rick@Synergy

iTrader: (5)

What do the plugs look like?

Rick

VaNDaL*SS*

iTrader: (1)

1. Intake
2. All other 7 look almost exactly the same.
3. Not sure
4. When I looked at them on saturday I did not notice this nor did my uncle (he is doing my rebuild)
5. I believe on the #7 piston (which is the one that let go) from what i remember shows somewhat of a polished look to it, but do not qoute me on that, i will have to look when i head up there again this weekend.
6. I do not remember at all another thing to look at when I head up there agian.

I did not see the plugs, one more thing to check out when i get back to his shop.

Sorry about the pix guys it was on my camera phone. When i go back i will get better pix for sure. Is there anything else I should look for?

AcE XBOX

Damn dude that sucks. I was really looking forward to see your car run on the street. So many problems man. Hope it all works out for you. Isnt this the third rebuild?

wait4me

iTrader: (10)

From the shiny polished part of the piston skirt, Doesnt that mean too small of a piston for the size of the bore and the piston was rocking back and forth in the cyl?

slpss9723

this is the second story i've heard of #7 going after MTI suggested everything would clear.....my buddy here in abilene upgraded to a bigger cam from them and was told everything would clear and work well.....but the first time he drove his car, it fucked up.....he ended up with metal in his pan, in his intake, etc. it was pretty bad.....i wonder what's going on down there lately......

LIL SS

iTrader: (9)

Ace, having the heads off the car is not a "rebuild". And the heads have only been off the car twice. Once to take the stock ones off and a second time to help a head gasket that did not seal properly.

Randy WS6

iTrader: (69)

been there done that ,Stock pistons are junk

TXCAMSS

iTrader: (60)

Man I hate to hear that man. I think you already know my thoughts on the situation. I sure wanted to see what kind of times you were going to get out of it.

Keep us posted on the rebuild and diagnosis.

Frost

iTrader: (45)

#7 failure is very common in boosted applications, especially when used with stock bottom end... In fact, when piston failure is involved, it's almost always this one first. (again, boosted apps)

All research (FI) seems to indicate that the number 7 cylinder seems to run leaner than the rest. I have seen it blamed on the intake design; #s 7 and 8 get more air, so they run leaner... This fact alone leads to a situation which facilitates detonation.... You could get your injectors flowed and put the highest flowing units on #7 and 8 in the future.

VaNDaL*SS*

iTrader: (1)

this is not a boosted app though, purely NA no power adders have been ran through this application.

dame

iTrader: (3)

Looking at your sig tells me you didn't cut any corners...... but did you have this tuned? if so could the tune have something to do with the detonation? or is that impossible?

LIL SS

iTrader: (9)

The WOT tune was done by me and is very safe.. 12.2-1ish AF and 28* timing. Watching every pull with EFI live there was 0 KR.

Rick@Synergy

iTrader: (5)

what type of dyno? The 28* is pretty high if you ask me. And where were you meassuring the AFR at?

Rick

LIL SS

iTrader: (9)

Dynojet.. Not sure on the exact model.

Ryan's car has dual electric cut outs just after the header collectors and in front of the cats. The wideband was put in the cut outs so basically in the header collector.

I see nothing wrong with the 28* timing. I've seen several different tuners run from 27-29* and they aren't back yard guys either. What do you typically run for timing Rick?

BTW, here is his dyno post.. https://ls1tech.com/forums/dynamometer-results-comparisons/368371-finally-got-my-setup-tuned-dyno-d.html