You are very lucky Wally! Glad that's the only damage done.

Wow ! I'm glad there was no other significant damage to your engine ! That is a very puzzling break for sure.

Sandeep

I'm glad you have past this with the less cost effectiveness.

It is odd that 2 broke on the same cylinder.I´ve seen that happen on V8 cars that ran into the rev limiter on their burnout,it happened to my Mustang back in 1992.I broke 3 rocker arms due to valve float when I ran into the limiter (set it lower after that;) ),but they were all on different cylinders.Other than that,I would say that they just wore out and broke,stress cracking and fatigue. But very lucky indeed that it didn´t take a bunch of other parts with it!

It's just too coincidental that they are both on the same hole side by side...

Detonation?

Evil Detonation, specifically?:)

No, its not from detonation, that I know for sure as I had the vid running showing the knock sensor not sensing knock when it happend.

Mark, its not from 'worn out' reasons either as no wear is visible. Wear by definition should always be measurable/visible. Not likely either as they run on DLC treated rocker shafts...
But I do also think pure metal fatique could be the most likely cause, probably combined or caused by a does of bad luck from coinciding ignition and/or fuel cut-outs all at once and overboost cut-outs during the tuning I did the days before. These are/can be rather violent.
I have no other explanation as these original rockers are really considered as 'unbreakable' otherwise.

Hi

I'm no metallurgist, could you take them to maybe a local aeronautical engineer and ask their opinion.

Steve

I've done a bit of failure analysis in the past, doubtful I could tell from photos but if you post closeups of both sides (broken side) I can at least take a look.

-Dave

something 4 the trophy shelf

Difficult to photograph so up close. This is the best I could do:
http://i174.photobucket.com/albums/w...1.jpg~original

http://i174.photobucket.com/albums/w...i.jpg~original

Yeah, the trophy shelf has another exibit for sure..

After replacing the two rockers by another set of used rockers :D , the engine ran flawless again yesterday on the Ring.

http://www.pistonspy.com/gallery2new...serialNumber=3

http://www.deinerunde.de/Nordschleif...s/IMG_4298.JPG

http://www.uedn.de/nos/T16042010/Images/DSC_0081.jpg

http://www.uedn.de/nos/T16042010/Images/DSC_0134.jpg

Also put some video up of the day on a vimeo account:
http://www.vimeo.com/user3613136/videos

what a GREAT video and some nice driving too ;)
keep it up man
Chris

Well, not so sure about the driving, but you can really check out the place this way and it shows what a great wheather we had!
Vimeo has an upload limit....so I'll try to upload some other footage onto my y-tube account:
www.youtube.com/user/fusca03

I just read through your whole build and your car is just AWESOME.. :goodjob:

amazing pictures again wally :) looks like you;re havin great fun with the car!