2003 Pilbeam MP91

Images copyright and courtesy Bob Chapman @ Autosport Image
Text and images copyright Michael J. Fuller

The MP91 still retains the MP84's side NACA cooling duct though it has increased in size and extends much further forward.  Air management at the front end is revised with the addition of the large duct exiting at the trailing edge of front wheel well.  The duct primarily functions to pull diffuser air from the underbody though it would appear that wheel well air is siphoned off as well.
The underside of the front diffuser is of interest.  Three NACA ducts adorn each side of the bottom with at least one providing cooling air for the front brakes.  The function of the other two is somewhat of a mystery, though the duct furthest inboard (and probably the one next to it as well) clearly works in conjunction with the diffuser kick.
Air taken into the NACA duct blows over the top of the diffuser kick enhancing its action.

©Copyright 2003, Michael J. Fuller