Just read the sticky on TV. It is still not clear to me if there is a relationship between the rpm of the shaft and the overall force of the vibration. In a straight-4 engine would the torsional vibration be worse at higher rpms than the same type engine at lower rpms at the same power. In other words, take two straight-4 engines of the same displacement, one engine turns at 3000 rpm at 100HP, and the other at 6000 rpm at 100HP. All else being equal would the higher rpm engine produce more vibration, or less, or equal?