My Camaro went home to Oshawa to die......

[2010 L99]

From dead 6/10/11 to alive 7/23/11. Excellent effort.

[Darth_Emma]

I'm astounded at how quickly you got the car up and running again.

It took 3 months this spring for my shop to do a cam and some suspension upgrades to my car.

[Nvincent4708]

Originally Posted by Darth_Emma

I'm astounded at how quickly you got the car up and running again.

It took 3 months this spring for my shop to do a cam and some suspension upgrades to my car.

GOO!

Hugger and I both did this..We should have our own "zombie" territory at Oshawa next year.

Mine Died 05/29/11
Mine Alive 06/13/11

[OrangeVert]

Congrats, Mike!

[Huggerorange73]

Originally Posted by Nvincent4708

Oh Noes!

Not that bottle thing!

Supercharger or bust!

To be 100% honest, I'd much rather prefer to stay NA. The LS3 is built around specs and materials for NA applications. Boost or bottles scare the hell out of me. I'd much rather not go through this again.

Originally Posted by 2010 L99

From dead 6/10/11 to alive 7/23/11. Excellent effort.

Thanks much for the compliment, and your service!

Originally Posted by Darth_Emma

I'm astounded at how quickly you got the car up and running again.

It took 3 months this spring for my shop to do a cam and some suspension upgrades to my car.

See, maybe I should be doing all your work

Originally Posted by Nvincent4708

GOO!

Hugger and I both did this..We should have our own "zombie" territory at Oshawa next year.

Mine Died 05/29/11
Mine Alive 06/13/11

I like this idea.....I'm also giving serious thought to getting those ZOM BEE plates!

Originally Posted by OrangeVert

Congrats, Mike!

Thank you!

[AnnaBear@SpartaChevy]

Hi Mike!

LOVE the 'ZOM BEE' plate idea.


lmao

[Huggerorange73]

Originally Posted by AnnaBear@SpartaChevy

Hi Mike!

LOVE the 'ZOM BEE' plate idea.


lmao

It's the undead Camaro.......

[Darth_Emma]

plate could read... "BRAINS"

[Huggerorange73]

Originally Posted by Darth_Emma

plate could read... "BRAINS"

No wait...somebody might think I'm smart then!

[SUX2BU]

Originally Posted by Darth_Emma

I'm astounded at how quickly you got the car up and running again.

It took 3 months this spring for my shop to do a cam and some suspension upgrades to my car.

Sounds like you need a new shop! That should have taken a day or two.

[Darth_Emma]

Originally Posted by SUX2BU

Sounds like you need a new shop! That should have taken a day or two.

Nah, to be fair, I had a ton of other stuff done this spring. They dropped the whole bottom of the car... tranny work, suspension work and they took the whole motor apart and rebuilt it. I was just trying to be funny.

[SUX2BU]

Originally Posted by Darth_Emma

Nah, to be fair, I had a ton of other stuff done this spring. They dropped the whole bottom of the car... tranny work, suspension work and they took the whole motor apart and rebuilt it. I was just trying to be funny.

"I see!" said the blind man.

[skip_168]

It looks like you had a piston failure due to mechanical interference with the valves. Everything else happened after the fact.

All failure events are the result of multiple failures in what we call the "chain" or chain of events leading to catastrophic failure. Basically, these were the factors that when any single contributor is eliminated, the failure would not occur. I backtracked through all of your photos and mods and came up with the following key contributors to your failure (not in any specific order):

1. the camshaft
2. The tune
3. the Hyper-eutectic pistons
4. the installation itself

1. The camshaft:

The increased duration and lift of the new camshaft reduced the valve-piston clearance. From my research this value is around .125 or so for the LS3 engine. This value is set for a specific operating RPM. The higher the rev’s the more the valve’s actual numbers detach from the camshaft profile through float, or valve inertia, thus adding a mechanical “rev limiter” to any engine. What the GM people did was set the rev limiter for the specific cam profile, plus a little headroom for inertial over-rev past the fuel cut-off. What this meant for GM was to allow mods to the camshaft profile without re-tooling of the pistons or valve train, a huge cost savings.

2. The Tune:

Increasing the rev-limiter was another link in the chain. For the reasons explained above, increasing the rev-limiter would require an increase in the valve-piston clearance to allow for the higher RPM’s and dynamic increase in duration and lift. So now, with the new cam in, reducing the valve-piston clearance and the rev limiter increased requiring the increase of the valve-piston clearance, the stage is set for an unhappy rendezvous between the two.

3. The Pistons:

Here is the sleeper. The piston in the LS3 are hyper-eutectic. This means they have a higher mix of silicon mixed in with the aluminum than would normally be accepted through chemical bonding/mixing of the alloy. GM did this because of one key property; expansion over temperature. A hyper-eutectic piston will not expand as much as other aluminum alloys, therefore the clearances could be designed much tighter and not vary too much over the operating temperature range. The drawback to this process is that hyper-eutectic pistons are brittle. In other words, they don’t bend, they shatter.

4. The installation:

The cam company looks at the valve-piston clearance with great scrutiny. It’s one of their primary design parameters. It governs the lift & duration they can grind their cams to, and then work backwards to satisfy drivability. They probably assume the same operating RPM range that GM designed, and recommend a t most a spring change to compensate for the reduction in the valve-piston clearance. The cam engineers probably didn’t know you were increasing the rev-limiter, and the installer probably didn’t know it would be an issue.


Your detonation timeline kinda goes like this:

1. clearly the valves were hitting the pistons, how often and how hard were governed by the frequency of high revs, (near the red-line) occurred.

2. The pistons’ brittle nature came into play next. As soon as they cracked from the impact of the valves, the rest happened in milliseconds:

A. Piston #1 cracks completely, followed by piston #7 almost at the same time,
B. the rods are free to do their destruction, punching holes in the block, etc.,
C. the rods punch through the valley/camshaft area and jam the camshaft,
D. the cam-pin shears, allowing the cam to go out of time almost 180 degrees of crankshaft rotation,
E. The rest of the valves get hit as the RPM’s drop to zero.


This of course is an opinion based on your photos and inputs, so its accuracy is limited to the accuracy of the photos and your description of events. The key clues that led to this conclusion were the two broken pistons. I have never seen two pistons break on opposite ends of the engine at the same time or close to it. I know you mentioned #1 connecting rod failure as a possibility, but that did not explain why #7 had a failure as well. Then there are the marks on all the pistons. This indicates either a timing problem or an interference problem. Now, timing a camshaft is pretty simple on a GM: line up the dots, and away you go. I doubt the install guy got this wrong. Plus, the owner never complained of drivability issues which would surely be notice had the camshaft been out of time. Here the most important clue. On some of the pistons, carbon had started to build back up on some of the witness marks or “rings” left on the tops of the pistons. This clearly would not be possible in the short amount of time after the detonation; therefore they pre-dated the final detonation and were the initial “spark” to your LS3 melt-down.

[Huggerorange73]

Originally Posted by skip_168

It looks like you had a piston failure due to mechanical interference with the valves. Everything else happened after the fact.

All failure events are the result of multiple failures in what we call the "chain" or chain of events leading to catastrophic failure. Basically, these were the factors that when any single contributor is eliminated, the failure would not occur. I backtracked through all of your photos and mods and came up with the following key contributors to your failure (not in any specific order):

1. the camshaft
2. The tune
3. the Hyper-eutectic pistons
4. the installation itself

1. The camshaft:

The increased duration and lift of the new camshaft reduced the valve-piston clearance. From my research this value is around .125 or so for the LS3 engine. This value is set for a specific operating RPM. The higher the rev’s the more the valve’s actual numbers detach from the camshaft profile through float, or valve inertia, thus adding a mechanical “rev limiter” to any engine. What the GM people did was set the rev limiter for the specific cam profile, plus a little headroom for inertial over-rev past the fuel cut-off. What this meant for GM was to allow mods to the camshaft profile without re-tooling of the pistons or valve train, a huge cost savings.

2. The Tune:

Increasing the rev-limiter was another link in the chain. For the reasons explained above, increasing the rev-limiter would require an increase in the valve-piston clearance to allow for the higher RPM’s and dynamic increase in duration and lift. So now, with the new cam in, reducing the valve-piston clearance and the rev limiter increased requiring the increase of the valve-piston clearance, the stage is set for an unhappy rendezvous between the two.

3. The Pistons:

Here is the sleeper. The piston in the LS3 are hyper-eutectic. This means they have a higher mix of silicon mixed in with the aluminum than would normally be accepted through chemical bonding/mixing of the alloy. GM did this because of one key property; expansion over temperature. A hyper-eutectic piston will not expand as much as other aluminum alloys, therefore the clearances could be designed much tighter and not vary too much over the operating temperature range. The drawback to this process is that hyper-eutectic pistons are brittle. In other words, they don’t bend, they shatter.

4. The installation:

The cam company looks at the valve-piston clearance with great scrutiny. It’s one of their primary design parameters. It governs the lift & duration they can grind their cams to, and then work backwards to satisfy drivability. They probably assume the same operating RPM range that GM designed, and recommend a t most a spring change to compensate for the reduction in the valve-piston clearance. The cam engineers probably didn’t know you were increasing the rev-limiter, and the installer probably didn’t know it would be an issue.


Your detonation timeline kinda goes like this:

1. clearly the valves were hitting the pistons, how often and how hard were governed by the frequency of high revs, (near the red-line) occurred.

2. The pistons’ brittle nature came into play next. As soon as they cracked from the impact of the valves, the rest happened in milliseconds:

A. Piston #1 cracks completely, followed by piston #7 almost at the same time,
B. the rods are free to do their destruction, punching holes in the block, etc.,
C. the rods punch through the valley/camshaft area and jam the camshaft,
D. the cam-pin shears, allowing the cam to go out of time almost 180 degrees of crankshaft rotation,
E. The rest of the valves get hit as the RPM’s drop to zero.


This of course is an opinion based on your photos and inputs, so its accuracy is limited to the accuracy of the photos and your description of events. The key clues that led to this conclusion were the two broken pistons. I have never seen two pistons break on opposite ends of the engine at the same time or close to it. I know you mentioned #1 connecting rod failure as a possibility, but that did not explain why #7 had a failure as well. Then there are the marks on all the pistons. This indicates either a timing problem or an interference problem. Now, timing a camshaft is pretty simple on a GM: line up the dots, and away you go. I doubt the install guy got this wrong. Plus, the owner never complained of drivability issues which would surely be notice had the camshaft been out of time. Here the most important clue. On some of the pistons, carbon had started to build back up on some of the witness marks or “rings” left on the tops of the pistons. This clearly would not be possible in the short amount of time after the detonation; therefore they pre-dated the final detonation and were the initial “spark” to your LS3 melt-down.

Thanks for taking the time out to do this......hopefully everyone walks away smarter from this!