I recently had a similar incident with a piece of the plug coming apart and damaging the piston. Will be sharing more in the coming days after we investigate further. Hopefully this is helpful info to anyone considering alternative spark plug options. The plug in my case was a Denso Iridium IXU22, which was specified for my Sharkwerks 3.9L build. Picture of the piston below:

 

Very sorry to hear-please post updates when possible-
Bosch discontinued the Y5DDC plugs for the GT3.
After extensive searching (and I even called and spoke to the Bosch US rep)they will no longer make the plug-quite bizarre.
The closest plug to the original is NGK, and I posted on an extensive discussion on another thread not long ago.

The NGK equivalent to Bosch Y5DDC is DCPR8EKC

 

NGK > BOSCH.

 

The Y5DDC is still available through Porsche as 99917012990 at $30ea! Long gone are the days of $8, maybe Porsche has an OEM agreement and cornered the market, I don't know.

I just ordered 12.

Here is a pic sent to me this morning.





One another note JMC sorry to hear about this, do you have pics of whats left of the spark plug? How many miles on the plugs?

 

I went into a few BMW dealerships this summer and was able to get 12. They are still out there… but you’re going to have to search for them.

 

Can you guys explain how a piece of ceramic ended up inside the cylinder? Isn't the ceramic part of the plug stays outside? Thank you.

 

I have a set of Bosch in the Porsche boxes, last ones I could find on eBay a while back-I'll be putting them in soon as it approaches the 4 year interval:

But it doesn't make much sense to pay insane prices for these, when the NGK costs less than $10 at most suppliers-
And back when Y5DDc plugs were widely available, many Mezger owners were aware that there were the Porsche packaged ones, and the Bosch packaged ones. The ones in the Porsche box cost 3X more Some of the Bosch packaged ones had blue stripes:Others also had green stripes but the tips were different like the blue ones above:

I've been using NGKs on all my motorcycles for years, and usually order by stock number. In this case, for Mezger GT3s, stock number 7168:
https://www.ngk.com/ngk-7168-dcpr8ek...und-spark-plug

Even Ebay has them for about $7.50 each:
https://www.ebay.com/itm/29453609873...cAAOSwW4hhi1Gu

Motorcycle shops also sell them, so finding them should be no issue-

JB

 

Robocop, look again at what surrounds the center electrode-ceramic-

The original thread of a catastrophic plug issue:
https://rennlist.com/forums/997-gt2-...ure-found.html

Best,
JB

 

Sorry to hear about the engine incident. I wonder what was the symptoms that issue must have caused. Keep us posted.

 

That's a very long thread-apparently the complication was from an incorrectly positioned fuse(fuel pump)
At high rpm that engine was lean and that's what destroyed the plug-
Crazy

JB

 

JMC376, any update on your case? How does it compare to the one outlined in this thread?
https://rennlist.com/forums/997-gt2-...ure-found.html

At the end of that discussion, it seems like the cause was the mis-installation of the fuel pump fuse(s), causing a lean condition at high rpm.
I have read in other posts, some of the DIY oil change ones, about the practice of removing the fuel pump fuse, to crank the engine without starting it after the oil change, so oil gets pumped around to prime the motor-something I consider unnecessary-catastrophic because the fuses were re-installed out of order, and even more bizarre is the fact that the car ran like that
But in the middle of that discussion there is another poster that mentioned another case of a disintegrating spark plug-there were no more details given in his case-

I hope you can sort out what happened to yours-
JB

 

Looks like RockAuto has 1 remaining.

https://www.rockauto.com/en/moreinfo...bC8%2FOmL7wRdk

 

I installed NGK as noted in other thread this past summer. No hiccups to date - high rpm testing

 

If you saved the used Bosch ones, it would be nice to see pictures comparing them to the NGK after some use-
Best,
JB

 

Unfortunately still not certain what caused the failure. Engine was running great for almost 2k miles since the last plug change when the failure occurred. It did occur right after a fuel fill-up (93 octane), so perhaps bad gas contributed. I will try to get a picture of what remains of the plug and post.

It's also relevant that this happened in a Sharkwerks 3.9L engine build. They specify a shorter replacement interval for plugs, only 2,000 miles, so perhaps the additional stress they are subjected to vs. OEM setup was also a contributor.