I'm working on bearing development in my daily job. I'd say that con rod bearing in your photos has run dry, maybe you're creating too many g's on the track! Baffled sump required?
Even if the bearing finally let go on the city street the damage could have been done earlier, a small scuff could have been made on the bearing surface when running dry or under low pressure which has gradually got worse over time to the point when a lump of aluminium has come loose and been dragged around the bearing leading to the catastrophic failure in the photos.
My experience is mainly in polymer bearings but that's the advise I'd give based on my limited aluminium bearing test work.