Last sunday my engine blew up while at track. Car was running good until this session when taking out from hot pit there was little misfire. Sounded like one cylinder cutting out but it cleared up soonest I got to 3rd gear. Lap later I heard ticking and car lost power, by the time I stopped there was loud knock and smoke coming inside of the car around shift lever. No smoke outside or any oil visible anywhere.
I thought it sounded like rod knock but this morning I found different issue. One of the coils was destroyed and 2 spark plugs I can't even get out. Looks like some serious detonation going on inside the motor. Motor is stock and was running 91 pump gas. Anybody had something like this happen?

 

not certain but looks like the spark plug worked itself loose and caused the failure

 

I took plug out, it was still screwed in the head. Coil was in that shape tho. However other 2 cylinders I can't take plugs out, think they are damaged on threads exposed to combustion chamber. Will know more once motor is out and I take head off.

 

The two that are stuck are likely fused at the threads due to gases melting them if that is what happened. probably bits of the plug melted to the piston as well

 

The 2 stuck plugs, crack loose barely, with all your might then spray a pentrating lube down the tube and let sit over night. Then retry to remove. At this point whats the worste that could happen. Plug break?

 

At this point motor is coming out and no point of trying to remove those plugs. Piston top in bad coil cylinder looks like all blasted shiny aluminum. Other one looks normal as far I can see through plug hole.

 

I had the same thing happen to me and another friend. You have to check your torque on your plugs after track days or Auto-X. My plugs had backed out, one completely then broke into a bunch of motor mashing pieces. :-( Head damage and cylinder damage, swapping the motor out next week. After I break down the old motor I can give more details.

 

20ft-lbs is what I use on my plugs

 

But what would damage coil to this point if plug was still in there? It is broken apart on the top and part fitting plug is all screwed up and whole thing split along. I would think coil itself had some problem causing rest.

 

While the plug was loose but not yet welded to the head the escaping gases destroyed the coil pack. if you search the under the hood forum you'll see similar problems people have had to this with regard to loose plugs