I've yet to see any witness accounts that are consistent with an explosion (and trust me, I've spent a fair amount of time looking). The post crash video looks like an 'ordinary' post crash vehicle fire to me. I don't see any signs of an explosion.
What happens to the engine depends very much on how the impact occurred, and the energies involved. I've seen a handful of wrecks where some substantial piece of the vehicle (engine, transmission, etc) was tossed a long distance. Incidentally, all of those were very high speed collisions, and they all involved at least one fatality. There were all slightly off-axis impacts trees or very solid posts, where the point of impact was about halfway between the midline of the vehicle and one of the front corners.
What happens to the engine depends very much on how the impact occurred, and the energies involved. I've seen a handful of wrecks where some substantial piece of the vehicle (engine, transmission, etc) was tossed a long distance. Incidentally, all of those were very high speed collisions, and they all involved at least one fatality. There were all slightly off-axis impacts trees or very solid posts, where the point of impact was about halfway between the midline of the vehicle and one of the front corners.