1991-1993 Toyota Eagle MkIII

Images copyright Michael J. Fuller and Ryan Hicks
Text copyright Michael J. Fuller

The Eagle MkIII wasn't the first sports cars to utilize a front underbody aero concept designed to develop downforce.   Even the very first GTP cars were looking in that area to generate localized low pressure to improve front balance.  But the MkIII was most definetly the first to take that concept to the next step by intentionally exiting the airflow from the front diffuser out the side of the car and fully providing for as clear a path as possible, both into and exiting the diffuser, for the airflow.
Tony Mathews drawingThe diffuser forms wings either side of a central "bubble", that is, a  surface undulation that blends back tangent to the floor but causes a local pressure reduction.  The diffuser wings then extend from the bubble section to just with in the front wheel well and utilizes the spinning action of the front wheels to further draw airflow though the bubble and the diffuser.
Here we can see the wings of the diffuser upsweep and their proximity to the wheel and suspension members.
In this shot the front splitter has been removed (hence the daylight in the top portion of the image).  Here you just begin to get an idea of the clear path the airflow has out the car via the outlet aft of the front wheel.

©Copyright 2008, Michael J. Fuller