The intake valve seat is gone. It got loose in its bore and fell out. It got trapped by the intake valve and when the piston came up and hit it, the seat fragmented, That's what bent the intake valve. The pieces of hardened valve seat got beat into the piston crown-which mushroomed the piston- which now is too tight in the bore and generating heat. I've seen it happen dozens of times. No fuel problem, or detonation problem, or advanced timing causes damage like this. This engine dropped an intake valve seat. NO mystery here.