Hot spots between cylinders because of siamesed cylinders that block coolant from circulating around the whole cylinder has been known forever. I just don’t know why they make all engine like this today, 4 cylinder, V-6 and V-8. I don’t know any manufacturer that doesn’t do this today. The added pressure in the cylinder from turbo-charging must be pushing the engines to destroy the head gasket , problem is not as bad in naturally aspirated engines.
