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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
There is a low mileage bone stock 08 a half our away from me with a blown engine for sale on Craigs List. He's not going to fix it but is holding out for way to much money. He wants 26K for it. You can buy 08's in the low 30's all day long so 26 is crazy. Told him when it gets down to 20 call me. Even at that, it's to high.
There is a low mileage bone stock 08 a half our away from me with a blown engine for sale on Craigs List. He's not going to fix it but is holding out for way to much money. He wants 26K for it. You can buy 08's in the low 30's all day long so 26 is crazy. Told him when it gets down to 20 call me. Even at that, it's to high.
I'm assuming that because he was on a track, he's a HPDE driver of some sorts.........if so, wasn't he aware of this issue before purchasing and running his Z06 ?
I'm assuming that because he was on a track, he's a HPDE driver of some sorts.........if so, wasn't he aware of this issue before purchasing and running his Z06 ?
Originally Posted by MTPZ06
Sucks that a couple grand could've avoided this very costly repair. OP, was your boss aware of the risk?
Yes he was, we were going to pull the heads over Thanksgiving weekend and send them out.
I'm assuming that because he was on a track, he's a HPDE driver of some sorts.........if so, wasn't he aware of this issue before purchasing and running his Z06 ?
Correct, we were at Roebling Raceway in Savannah Ga. We were very aware and we were going to pull the heads Thanksgiving weekend and send them out.
Why does everyone jump to dropped valve, especially when it was done at a track? I've lost numerous engines of all types at tracks that looked like this. Detonation, poor valve piston clearance due to many variables, over reving, ring land loss; Jeezz. There are so many things that could have caused this its not funny. Get educated people. Go ahead start the flaming.
Why does everyone jump to dropped valve, especially when it was done at a track? I've lost numerous engines of all types at tracks that looked like this. Detonation, poor valve piston clearance due to many variables, over reving, ring land loss; Jeezz. There are so many things that could have caused this its not funny. Get educated people. Go ahead start the flaming.
Sooo, you've lost multiple engines, and you can't concede that maybe you don't know wtf you're talking about? right.....
Certainly the valve made contact and is no longer in the head. So yes, it dropped. My question is did the valve drop out of the head and/or lose the valve head off the stem due to the LS7 valve issue and then the chain reaction started? Or did something else contact the valve causing it to drop out of the head? In the second scenario of course a different failure mechanism caused the valve to "drop" other than the LS7 Valve issue. And yes over 45 years of driving hard many cars I've lost a few. Stretched timing chains, floating valves, detonation, a fractured spark plug, etc, and many look like that in the aftermath. Perhaps I missed something that others clued in on from the photos and for that I apologize in advance....
Sure...there can be more than one way to grenade an LS7; but my take aways... Its a "one owner" 2007. I can only surmise this as being a bone stock car, but OP please correct me if I'm wrong here. I see in the first photo the cylinder head is missing the exhaust valve head. Its somewhat of an understanding that earlier model years had a higher propensity to snap an exhaust valve. Around May of 2008, GM had a part number change for the C6Z exhaust valve, due to a change in suppliers. Many of us feel the change in suppliers was due to QC issues with the previous supplier's manufacturing. I'd have to dig a bit more for the exact numbers, but the newer OEM exhaust valve had thicker (more consistent) walls...bumping up to something like a wall thickness of .041"
Early ('06-'08) valve inconsistencies in wall thickness, as well as variances in the amount of sodium fill were discovered:
These inconsistencies in wall thickness, coupled with the non-concentric guide to seat machining courtesy of Linimar would over time lead to stressing the valve in a manner such as this...
Exhaust valve discoloration (different from others) due to inadequately amounts of sodium fill:
There's a ton of old/archival information here that can be sifted through, but at the end of the day...I personally feel this was a good old fashioned exhaust valve failure.
Again OP, if your boss's car is highly modified, tuned, etc., the cause of the failure may be different than I described. Crap tunes by inexperienced "tooners" usually result in a lean condition that will more often than not crack the "#7 cylinder liner". Do you know which cylinder failed on the car?
11-10-2018, 07:13 PM
Add another one to the dropped valve list.
