1993 Joest Porsche 962C
Images courtesy and copyright Jeremy Banks and Michael J. Fuller
Text copyright Michael J. Fuller
Sebring 1991, Joest Porsche 962CIn 1989, and with the help of Norbert Singer, Joest Racing abandoned the traditional Porche 926 factory tail in favor of a remote rear wing which allowed a greater freedom of adjustment and improved overall aerodynamics.  Here is the car at Sebring in 1991; the Joest Porsche is relatively stanard but for the remote double elemet rear wing and revised tail.
Joest Porsche 962C, Sebring 1993Sebring 1993.  The Joest team had been busy, again with Norbert Singer as a consultant.  The nose notch had been filled in and air management exiting the front wheel well was revised.  Cooling airflow routing and turbo induction were also modified.  Joest abandoned the Kamm-ish rear end for a duck bill and complemented the package with a rather impressive twin tier rear wing.  Most of these changes had race debuted in a slightly different form the year before at Road Atlanta, though the rear wing had gone through one final iteration (image left).
Joest Porsche 962C, Road America HSR, 2002, Copyright Mike Fuller 2003The "Red Baron" twin-tier wing worked as two devices in one.  The upper plane functioned as a standard wing, running in the cleaner air at the maximum legal height.  It could be run flatter for the same level of downforce but less drag.  The bottom tier functioned as an under wing extractor, enhancing the downforce generated by the tunnels.  Notice that the main plane elements for both the top and bottom tiers are the same profile while the flaps are of dramatically different chord.
Joest Porsche 962C, Silverstone Historic Group C 2007DPS Composites originally manufactured the wings, endplates, and mounts.
Joest Porsche 962C, Silverstone Historic Group C 2007Wheel well airflow evacuation detail.  Basically the corner has been cut on the wheel well trailing edge encouraging airflow to follow that route out the side of the car.
Joest Porsche 962C, Silverstone Historic Group C 2007The horizontal plate in the radiator intake is a legality valance plate.   In the early 90s regulations were added that stated that when viewed from the above, mechanical components (suspension, radiators, etc.) had to be covered.
Joest underbody, Atlanta, 1993, Copyright Mike FullerWith all the work that Joest had done to the top sides it was surprising to see that the underbody was still pretty much as the factory had developed.  Notice the metal sheets hinting where the wide engine resides; the width of the Porsche flat-six motor really affected the packaging of the underwing.  To that extent, the entire drivetrain (engine, bellhousing, and gearbox) was angled slightly to attempt make up for that deficiency.  

Also note the factory underfloor update, the horizonal extension (arrow) projecting inboard which helps enhance the vorticie shed as the air pours into the tunnel section.
Joest Porsche 962C, Atlanta, 1993, Copyright Mike Fuller 2003Another view of the Joest 962C.  In this case, the Atlanta IMSA GTP race in 1993 (Road Atlanta was being paved).  The vents behind the front wheel well have been covered up with a flat plate to just a thin slit.  Though a very small gurney lip has been added to the leading edge of the slit in order to provide for some wheel well extraction.
Joest Porsche 962C detail, Atlanta, 1993, Copyright Mike Fuller 2003The cooling package is still pretty conventional.  The Porsche's coolers (water, oil, and turbo intercoolers) were located in the side pods and fed by intakes in the doors.  Joest modified the cooling exit by allowing some of the air to exhaust out vents in front of the rear wheels, the rest exiting out the engine bay at the rear.  Notice the periscope turbo intake.
Joest Porsche 962C, Atlanta, 1993, Copyright Mike Fuller 2003A double set of large dive planes has been added to the nose to further augment front end grip.  Note the thin splitter across the front that integrates into the lower diveplane.

Wind tunnel development of the Joest Porsche 962C was carried out at the Porsche Weissach tunnel (full scale fixed-floor with boundary layer suction).  According Ralf Jüttner, Technical Director for Joest Racing, maximum downforce for the Joest 962C was 5584 lbs. for 1396 lbs. drag (max L/D: 5281 lbs. downforce for 1200 lbs. drag).  Jüttner also mentioned that, "In general, I think we were quite far off the downforce values of the Nissan and the Toyota.  Anyway, I do know that downforce figures from the Weissach tunnel showed smaller values compared to other tunnels.  But regardless, there was no way coming close to the Toyota as we could personally see large differences in the braking points for the first chicane at Portland for example." 

Joest Porsche 962C, Silverstone Historic Group C 2007Mechanically the Joest car was standard factory 962.  Note the large composite nose box.
See the video of the 1993 IMSA GTP race at Atlanta Motor Speedway (right), brought to you by Marshall Pruett's website, Grand Touring Prototype.  See his Vimeo channel as well for tons of IMSA GTP videos.

GTP: 1993 Atlanta Motor Speedway Race Broadcast from GrandTouringPrototype.com on Vimeo.

©Copyright 2012, Michael J. Fuller