A centrifugal supercharger is provided. One embodiment of the supercharger comprises a two-piece housing wherein a parting area is substantially aligned with a rotational axis of a drive- or impeller shaft. Another embodiment comprises a sleeve, or intermediate member disposed substantially between the housing and a bearing assembly(s) located within the supercharger housing. Another embodiment comprises a disengagement device located between the supercharger impeller and the engine. The disengagement device allows selective disengagement of the impeller from the engine. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. This Abstract is submitted with the explicit understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.