1991-1992 Jaguar XJR-14

Images copyright Xavier-Philippe Lemierre, Sutton Motorsport Images, Bob Chapman @ Autosport Image, Paul Ajari, and Michael J. Fuller
Text copyright Michael J. Fuller

Porsche and Sutton Motorsport images used with permission

Jaguar XJR-14 Magny Cours 1991. Image used with the permission of Sutton Images. The Jaguar XJR-14 was designed in response to the new European sportscar racing regulations that did away with the fuel allotment formula (Group C) in favor of a single engine specification.  From 1991 onwards all cars in the Sportscar World Championship would have normally aspirated, 3.5 liter engines; the number of cylinders was free.  Chassis wise the regulations were still pretty familiar, but the minimum weight was lowered to 750 kgs (1650 lbs) from around 900 kgs (1980 lbs).  Thus the regulations, going into 1991, were a departure inasmuch as the package that it would take to win compared to years past.

Design development for the XJR-14 began in early 1990 when wind tunnel testing was initiated at the Imperial College wind tunnel in London.  Sixty days of wind tunnel testing would be carried out using a 40% model.  Solid aerodynamics and excellent weight distribution combined into a well sorted package (F1 proven Ford V8) and led to the XJR-14 winning the '91 Sports Car World Championship.  At its debut at Suzuka, the brace of XJR-14s were no fewer than 2.5 seconds ahead of the competition in qualifying and that time offset extended into the race.  The XJR-14 would go on to win the World Championship that year, but following the season Jaguar's Silk Cut sponsorship ended and the TWR Group C effort came to an end. 

Jaguar XJR-14, Road Atlanta 1992. Image used with permission of Sutton Images.With the European XJR-14 program shuttered, TWR then turned to their IMSA GTP effort.  In lieu of continued development of the Jaguar XJR-16, TWR would instead utilize the Jaguar XJR-14 for the IMSA GTP series in 1992 to high expectations but mixed results.  The very high downforce nature of US circuits and increased level of competition brought to the fore the Jaguar effort's weaknesses; namely ill suited wheels and the lack of an active development program--the XJR-14 raced in the US as it ended the 1991 season in Europe and most of TWR USA's development effort went in to modifying the chassis to better suit the US tracks.  It was also found that the wheels the Jaguar used could not handle the sustained G-loading seen on American road circuits and the team suffered two accidents (Lime Rock and Road America) as a result of wheel failures.  In the end TWR Jaguar only finished 3rd in the 1992 IMSA Championship, their worst showing ever in the IMSA series.

Three monocoques were manufactured for the original XJR-14 program;  chassis #591, 691, and 791.  These cars raced throughout the 1991 Sportscar World Championship.  The Jaguars were then raced in the IMSA GTP Championship the following year, with two out of the three suffering tub-damaging accidents at Lime Rock and Road America respectively.  The single undamaged chassis was eventually donated to the 1995 Porsche WSC program and would became a double Le Mans winner in the process (see below).

Mazda MXR-01, Le Mans 1992, Xavier-Philippe LemierreFor the 1992 Sports Car World Championship the XJR-14 became the Mazda MXR-01.  The MXR-01 program was a branding exercise that gained Mazda a quick entry into the World Championship by exchanging the Ford HB engine for a Mazda badged Judd GV V10.  The MXR-01 was essentially a mass produced XJR-14 and identical except for a few details (the tub was changed slightly to accomodate the longer Judd engine [the rear bulkhead inset 50-60 mm forward], Mazda tweaked the engine intake a bit, all details "costed" and productionized).  Unfortunately the MXR-01 found itself behind the development curve in Europe in '92 as well.

Five chassis were built for the Mazda MXR-01 program.

The XJR-14 would tangentially continue to have life beyond 1992 when its monocoque and bodywork (though modified) was donated to the Porsche WSC-95 program.  A joint project between former-rivals, TWR and Porsche, design work began in 1994 with the intent to enter the 1995 24 Hours of Daytona.  But a regulations change by IMSA, a mere 10 days before the race, caused Porsche to reconsider and withdraw the car.  TWR-Porsche WSC-95, early testingSubsequently further development was carried out and the TWR-Porsche WSC-95 was raced by Joest at the 1996, 1997, and 1998 24 Hours of Le Mans with overall wins coming in '96 and '97.
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1991-1992 Jaguar XJR-14 Specifications

Designer: Technical Director: Ross Brawn
Chief of Design: John Piper
Head of Aero: Mark Thomas 
Layout: Mid-engine, rear-wheel drive
Monocoque: Carbon fiber and aluminum honeycomb monocoque, with 4-point, bolt-on steel roll-over hoop.  Manufactured by Astec.
Engine: Jaguar badged Ford HB 3.5 liter normally aspirated 75░ V8, 4 valves per cylinder, DOHC
Horsepower: 670+ hp
Gearbox: TWR designed cast magnesium longitudinal 6 speed + reverse.  'H- pattern' gear change, left-hand shift.  AP 3-plate carbon clutch.
Steering: Rack and pinion, non-assisted
Suspension: F: Upper and lower A-arms, pushrod to inboard tub mounted torsion bars and horizontally (transverse) mounted Bilstein damper
R: Upper and lower A-arms, pushrod to inboard, gearbox mounted, spring/damper
Brakes: Front and rear ventilated carbon brake discs
Wheels: Speedline
F: 13.0 x 17 inch
R: 14.75 x 18 inch
Tires: Goodyear radial
F: 25.5 x 12-17
R: 28.5 x 14.5-18
Length: 4800 mm
Width: 2000 mm
Height: ~1092 mm (top of engine inlet with car @ 70 mm ride height, zero rake)
Wheelbase: 2807 mm
Front Overhang: 838 mm
Rear Overhang: 1149 mm
Weight: 750 kgs.
Tank capacity: 100 liters
Jaguar XJR-14 in Action
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ęCopyright 2010, Michael J. Fuller