What causes this to happen ?
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From: Winter Springs
What causes this to happen ? 
2k miles on the new build and this happens .
I have not sprayed this motor yet and now im glad i didnt .
What causes a chunk of the piston to go away like this ?
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From: Winter Springs
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If that motor only has 2K on it.. why is there so much oil buildup on the pistons? something doesn't look right with that, that's my first clue that something is wrong, very wrong.
fwiw the area where that piston broke, is awfully thin looking right where the valve relief is. I don't know what the spec was on the pistons, but if that broke like that n/a that piston, as well as every other one in the motor would have melted/broke very quickly even with a good tuneup.
fwiw the area where that piston broke, is awfully thin looking right where the valve relief is. I don't know what the spec was on the pistons, but if that broke like that n/a that piston, as well as every other one in the motor would have melted/broke very quickly even with a good tuneup.
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From: Winter Springs
If that motor only has 2K on it.. why is there so much oil buildup on the pistons? something doesn't look right with that, that's my first clue that something is wrong, very wrong.
fwiw the area where that piston broke, is awfully thin looking right where the valve relief is. I don't know what the spec was on the pistons, but if that broke like that n/a that piston, as well as every other one in the motor would have melted/broke very quickly even with a good tuneup.
fwiw the area where that piston broke, is awfully thin looking right where the valve relief is. I don't know what the spec was on the pistons, but if that broke like that n/a that piston, as well as every other one in the motor would have melted/broke very quickly even with a good tuneup.
I wonder what it would have done then ,, lol
That sucks Russ! Whenever i would hurt pistons in the purple Firebird on the big kit it was always in that same area of the piston at the very edge where the valve relief is, its the weakest spot.
Looks like maybe you had some good detonation that was enough to exploit that weak spot at the valve relief from under the ring land.
What were the specs on the build? Effective compression? Ring gap? How much timing? Type of fuel? It does look awfully oily too which I'm sure as you know will exacerbate tendency to knock if it's close otherwise. Do you have any logs of the car under power? Know if you were getting knock or how much capacity the car had to detect knock and retard timing?
I had that happen once on a N/A motor, and in that case, it was the only cylinder that showed signs of having had detonation so I chalked it up to an injector but never really knew for sure. Threw a new piston in it along with new injectors and never had another problem.
What were the specs on the build? Effective compression? Ring gap? How much timing? Type of fuel? It does look awfully oily too which I'm sure as you know will exacerbate tendency to knock if it's close otherwise. Do you have any logs of the car under power? Know if you were getting knock or how much capacity the car had to detect knock and retard timing?
I had that happen once on a N/A motor, and in that case, it was the only cylinder that showed signs of having had detonation so I chalked it up to an injector but never really knew for sure. Threw a new piston in it along with new injectors and never had another problem.
Without seeing what the other holes look like, he could have just ran it around for awhile broke which would have gotten that one looking nasty pretty quick. If they all are that black, then there's definitely another issue with oil control, tune, or both.
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From: Winter Springs
All the other cylinders were fine with just a hint of carbon .
When i pulled the plugs , all of them were fine except that one and it
was oil rich .
I have several logs and there was no kr with the car at 26 degree's .
Theres no sign of detonation .
When i pulled the plugs , all of them were fine except that one and it
was oil rich .
I have several logs and there was no kr with the car at 26 degree's .
Theres no sign of detonation .
It doesn't look like detonation when you see it up close. It's not a melted look to it. You can see the cast of the material around the edge of the broken piece and the bottom left corner of the broken piece is folded upwards, as if you were to take a piece of metal and fold it back and forth until it fatigues and breaks.
The pistons have a lot of piston to bore slop that doesn't show up in pictures. At TDC the piston will rock in it's bore pivoting on the pin. This happens on all of the pistons. #5 and #7 (7 is the damaged one) both have that light color to them on both the piston and the head at the quench area of the chamber. None of the others show this. could it have been the piston making light contact with the head?
Also, the bore measured at 4.035 but he was told the pistons being used were a .020 overbore piston. is 4.035 correct for any overbore and how much smaller should the pistons measure relative to the bore? I'm assuming there is supposed to be .002" per inch of bore, so they should be .008" under, or am I doing my math wrong? I tried searching here and on google and didn't find exactly what I was looking for
Also, the bore measured at 4.035 but he was told the pistons being used were a .020 overbore piston. is 4.035 correct for any overbore and how much smaller should the pistons measure relative to the bore? I'm assuming there is supposed to be .002" per inch of bore, so they should be .008" under, or am I doing my math wrong? I tried searching here and on google and didn't find exactly what I was looking for
could it have been the piston making light contact with the head?
Also, the bore measured at 4.035 but he was told the pistons being used were a .020 overbore piston. is 4.035 correct for any overbore and how much smaller should the pistons measure relative to the bore? I'm assuming there is supposed to be .002" per inch of bore, so they should be .008" under, or am I doing my math wrong? I tried searching here and on google and didn't find exactly what I was looking for
Also, the bore measured at 4.035 but he was told the pistons being used were a .020 overbore piston. is 4.035 correct for any overbore and how much smaller should the pistons measure relative to the bore? I'm assuming there is supposed to be .002" per inch of bore, so they should be .008" under, or am I doing my math wrong? I tried searching here and on google and didn't find exactly what I was looking for
If there is no porosity or crispiness on the piston and no pitting in that chamber, it makes this a little more odd.
EDIT: looked at the pics on a better screen, the top does look like it got a little hot or knocked on as mentioned above. Still hard to tell without being there.
Got any pics of the chamber?
Whats your setup (motor, heads, chamber vol, headgasket, cam specs)? My theory on strokers with a lot of effective compression (not sure if yours does) is that even though they may run and log fine on pump gas, you gotta watch them and be somewhat conservative. May be fine one day, then you fill up with some sub-par gas and maybe get some oil in the chamber on top of that, then do a long *** pull on the highway and before you know it you hurt your N/A motor.
Last edited by SSP Racing; Nov 16, 2009 at 09:22 PM. Reason: Pics of chamber?
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From: Winter Springs
It rattles like a diesel truck to the point of being anoying untill it gets up to temp .
Its an 404ci lq9 using a stock mls 6L gaskets and had 225-227psi/warm , afr 225 heads with 62cc chambers , comp cams 238/242-610/615-113+3 running 26 degrees with 93 octain and tr55 ir plugs .
Its an 404ci lq9 using a stock mls 6L gaskets and had 225-227psi/warm , afr 225 heads with 62cc chambers , comp cams 238/242-610/615-113+3 running 26 degrees with 93 octain and tr55 ir plugs .