Quote:
Originally Posted by TrackRat
OP - I can't answer your dealer issues.
If the sparkplug is from the cylinder with the damaged piston more than likely the closed sparkplug side electrodes are from the piston pieces hitting the side electrode and pushing them against the center electrode. This would have occured after the detonation/broken ring land. Pieces can also go up the intake and get sucked into another cylinder.
Pre-ignition can only occur if there is a hot spot. The sparkplug would not be glowing red unless it was extremely overheated via detonation or incorrect AFR, or something major. I believe the sparkplug damage resulted after the piston damage which was from detonation. A non-firing sparkplug would not cause pre-ignition. The fact that all the pistons and cylinders are scuffed and that you have unhappy bearings suggest detonation to me.
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You are right. My spark plugs has alot of scuffing marks on the side electrodes and the dealer / BMW Asia thinks I or some third party workshop used something to bend it in. Absurd! Piston 8 was damaged as well and it could be due to broken pieces of Piston 6 which was stamped on Piston 8 through the intake, etc. Piston 8 didnt have any problem with the spark plugs but I believe the damage was around from Bank 6. This is Piston 8 with pieces of Piston 6's autograph on it.
I was really all out on the car and it was very hot. It happened on the last few laps just before I was about to cool down. Its hard to speculate what it is exactly but its a painful lesson nevertheless.