Group C Jaguar XJR-6

In its first full season of racing the Jaguar XJR-6 achieved one world Sports Car Championship victory, at Silverstone in May and accrued enough points during the season to come within one place (at Fuji) of winning both the Team Championship and the Drivers’ Championship for Derek Warwick. Unlike all leading rivals it is powered by a normally-aspirated Jaguar V12 engine enlarged to 6262cc and developing up to 715 bhp though normally 680 bhp at 6500 rpm in race conditions.

XJR-6 was designed by Tony Southgate, acting as a consultant to Tom Walkinshaw Racing, in 1984/5 and, in turn, TWR operates the Gallahers Silk Cut-sponsored team exclusively on behalf of Jaguar Cars plc. The Group C car features a carbon fibre and Kevlar chassis and the body work was refined in the Imperial College wind tunnel in London. The tall venturi towards the rear, on either side of the narrow 60 degree angle V12, produces more ground effect than rival designs and gives the Jaguar an appreciable advantage on faster circuits.

When the XJR-6 first appeared at Mosport, Canada, in August 1985 it weighed 920 kg, despite which Martin Brundle was able to lead the opening laps of the 1000 kilometres race and eventually finished third. Prior to the 1986 season three new chassis were constructed with numerous detail improvements aimed at reducing the weight, the most notable being the installation of a single 100 litre fuel tank; when the XJR-6s appeared at Monza last April they were right down to the 850 kilogram minimum weight and were immediately competitive in the hands of Warwick, Eddie Cheever, Jean-Louis Schlesser and Gianfranco Brancatelli. Lack of turbo-charging handicapped the Jaguars during qualifying and they have never been on pole position but in economy controlled races they are competitive.

The V12 engine, developed by TWR in close collaboration with Jaguar Cars features TWR’s own management system and drives through a Borg and Beck clutch and a March 5-speed gear-box. 4-valve cylinder heads have been tested, but shelved on the grounds of weight and reliability, and AP’s twin-disc brake system was also tested last winter, though it has never been raced. The front suspension features dual wishbones and pushrod operated inboard horizontal spring/damper units, while at the rear the dual wishbones are suspended by outboard spring/dampers. Speedline wheels are 17inch diameter at the front, and the 19-inch diameter rear wheels are faired in by quick-release panels.

Special cars with lower venturi and rear body work were prepared for Le Mans, and will be raced again in the 24 hours this June.