Look how heavy the harmonic dampener is hanging of the front of one of these cranks
Plus i think i read that part of the crank spans the furthest distance un supported. I think some shop came up with some sort of stabilizer to help the issue but not sure on that. I thought i read it on here but who knows lol
Curtis Halvorson has made one and it works damn good for support...... but harmonics still break the cranks even with a internally balanced motor (with a procharger though)