From a quick study of the pictures I have to ask a few questions.
What type of injectors ? What type of fuel rails ? Which intake manifold and throttle body setup. More information on the cylinder heads would be helpful as well.Also what are the cam spec like ? Lift durations LSA ICL ?
Also there is evidence of some oil contamination. Chambers are really slimey.
without seeing the plugs in greater detail its tough to see exactly what happened here. To me most of them look a bit lean.They show signs of uneven combustion however. Only one side of the porcelin has colored.I would question the validity of the Wideband sensor data. I can't make a determination on timing. The shots of the plugs aren't revealing the ground straps in enough detail to see how they looked for tempature.
It definately started with some mild detonation but the look of the parts indicates a problem slightly more insidious. That looks like a burn through like what happens when the engine goes lean or has oil laying in the chamber or ring land. You can get micro detantion in the ring land and it will blow out small areas of the ring land and crown.
If the engine leans up to much it will thermally overload a thin area of the piston and the lack of fuel will cuase the piston to literally self combust.
Usually this problem is aided by a pinched ring land and oil consumption. Pinch the ring, it stops sealing and the oil combusts in the leanest area of the chamber and it will vaporize the piston.
Given the fact that you already toasted a set of head gaskets the condition of the ring lands must be called into question.
The piston has that look about it.
The detonation could be cuased by the leanout.
I really don't like what I am seeing as far as the combustion pattern on the cylinder head chamber and the Piston crown are concerned.It looks like the fuel is laying in the middle of the cylinder. but it also shows signs of fuel washing on the outer edges of the pistons or the edges of the piston are totally devoid of fuel.
This indicates to me at least that one of the problems your having here could be related to fuel distrobution and having the proper amount of swirl and tumble in the cylinder.
I would like to look at the parts first hand before making any further assesments.
I have a huge problem with detonation that just destroyed my engine. First off I will give you some info on the engine. It is a 363ci SBF with diamond pistons at 8.9 compression ratio with my heads. The pistons are built to match my trick flow heads. This engine was setup to run 20# of boost with pump gas. I first put the engine together with Felpro lamanate head gaskets. At 10# of boost with 11.7 air fuel and 10 degrees of timing, Poped both head gaskets. Pulled the heads, had them re machined. This time I used Multi layer steel head gakets. I took the car to Anderson ford for tuning and wanted to make sure the air fuel and timing was right. This time I set it up to run 18-19# of boost. We set the base run at 10 degrees of timing at boost, the air fuel ran at 10.5, and hit 19# of boost. Did a run and blew coolant out and broke the seam of the radiator. I pulled the engine apart and found #2 piston melted down to the rings and 2 other plugs ceramic broke. Horrible detonation. You cant hear it in the car, because it being so loud. This was done with 94 octaine fuel. I dont want to rebuild this thing just to get the same results. Any ideas or if you need more info please let me know. I cant afford for this to happen again.
