A torsion assembly for providing controllable torsion to a camshaft, including: a spring assembly including a first spring; and, a contact element arranged to engage at least one lobe for the camshaft. For a locked mode: the contact element is arranged to be displaced by the at least one cam lobe; the contact element is arranged to compress the first spring; and the first spring is arranged to impart a first torque to the camshaft via the contact element. For an unlocked mode, the contact element is arranged to be displaced by the at least one cam lobe and the contact element is arranged to impart a second torque, less than the first torque, to the cam shaft via the contact element.