MINI Cooper Performance by PROMINI: Taper Bore Pulley

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Part Number: 163988

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Taper Bore Pulley

The RPM of the supercharger is what determines the boost created in the MINI Cooper S. Reducing the size of the supercharger pulley, increases the blower RPM which increases the boost. The reduction size on the pulley increases the blower RPM by the same amount. This increases boost from the factory 10.5 PSI to 16.0 PSI with the 19% reduction pulley. We have experienced up to 20 HP increases, with torque improvement by as much as 22ft. lb. The impressive torque increase is what translates into some incredible acceleration. One of the main advantages of going with the 17% or 19% pulley over the 15% is that you are lowering the RPM where boost occurs which shifts your power band lower in the RPM range.