As I said, the inertia thing is mythical. The difference between a light and heavy crank would be barely discernable. Either way. We have an engine dyno. We were looking for the limits of 4.0 stuff. Our shop truck is bored .125" (daily driven 80Kmi, so much for the ".060" is too much" myth). We put the smallest pulley we had on a 9:1 motor. When 13# of boost didn't hurt anything, we started taking cuts off the head and running more and more compression. At .090" off the head, we were at 10.5:1 (so much for the "don't cut too much off your Jeep head" thing). The motor was detonating and ran like crap (essentially undriveable without considerable tuning) but it made power. The "light" crank, stock rods & bolts, no main girdle and used-10-times head gasket all held up. I am putting the "old mule" engine in my own brother's truck. So many issues are blown out of proportion by web wheelers, I say "Let 'er eat" . MIKE