Were fixing to find out. I am about to run 20psi on my 7.3 when its said and done. Sure its allot of force on the mains and rods, but it still only turns 3000rpm. If it makes 400hp I would die of a heart attack. The 7.3 block is made out of a stronger cast then a normal block as well as the mains. The parts don't seem massive but I can tell you they are strong. When I had it balanced the machinist was calling me complaining about the rods that they were heavier than a john deer inline 6 he did and that they were so hard he wasted 3 grinding stones grinding them just a bit to balance them. I really do think the bottom end will hold. What are the high powered powerjoke guys doing for there bottom end and at what power do they add stuff like that?