Lightweight crank pulley, MINI Cooper S R53 02-06. The Cooper S stock crank pulley weighs 7.2-lbs for 02-05 models. 05-06 models with build date after January 05 have a lighter 5.5-lb pulley. This stock-sized lightweight aluminum pulley weighs under 21 ounces (1.3 lbs). Since the pulley is stock-sized, there are no charging, reliability or compatibility issues. Less rotational mass equals quicker throttle response and more power!
Another feature is the steel center insert which accounts for 50% of total pulley weight. The steel insert gives strength where it is needed and ensures a minimum amount of weight towards the outer radius. Since the main area of weight is in the center, the energy necessary to spin the pulley is greatly reduced. Typical gains are 5-7hp depending on model year.
Note: This lightweight stock-sized pulley can be used with a supercharger pulley and will not affect the boost levels, only reducing the rotational mass.