A pulley has a hub and a rim. The hub is configured to be mountable on a driving shaft. A driving connection between the hub and rim is provided. In a first embodiment, a drive mechanism is operable to configure the rim between a circular profile and a non-circular profile. The non-circular profile produces a counteracting torque to offset load torques produced by the engine. The drive mechanism can be electrical, inertial, hydraulic or any combination thereof. In a second embodiment, the rim is fixed with a non-circular profile.