Abstract: A blower housing including a first and second rotor assembly such that the first rotor assembly includes a first rotor and a first shaft and the second rotor assembly includes a second rotor and a second shaft. The first and second rotors each have a plurality of lobes. Each first and second rotor includes an axial sealing extension that can be constructed to extend axially into the shaft opening. The axial sealing extension can include a radially outwardly facing sealing surface that opposes a radially inwardly facing sealing surface defined within the shaft opening. The radially outwardly facing sealing surface and the radially inwardly facing sealing surface can be configured to cooperate to form a radial sealing interface that extends around an axis. The radial sealing interface can include a radial seal clearance defined between the radially outwardly facing sealing surface and the radially inwardly facing sealing surface.