Changing just lobe orientation on the camshaft would not change duration though.
Just changing lobe position (valve opening and closing points - earlier or later) would not alter duration (shape of the lobe)
How come they say the SVT cams have more duration then?
I do agree that the lobe seperation angle is different. (110.5 degree for SVT & 116 degree stock - BIG difference!) However so is the duration. The power curves are too different to not have different durations. Just advancing the entire set of points would not change the curve; just move it up the rpm band. It is more of a change than that.
