With five victories in seven years Jaguar's reigned supreme at Le Mans in the 1950s, but rule changes left the highly successful D-Type obsolete after the 1957 season. Although the Works team would not field a racing car for many years, the racing department did develop the Lightweight competition version of the E-Type and the V12 engined XJ 13. After a heavy accident the XJ 13 project was halted, but the V12 engine was further developed and used in Jaguar's road cars. In the 1970s racing was left to privateers, although some did receive factory support through the proverbial backdoor.
In the early 1980s two of the most successful Jaguar privateers made plans to bring the marque back to Le Mans. Both Bob Tullius' US based Group 44 and Tom Walkinshaw's Britain based TWR had vast experience with the latest version of Jaguar's V12 and felt it could be a strong competitor in the newly created Group C class. This would mean taking on the mighty Porsches and that seemed virtually impossible without some structural factory support. Surprisingly this was granted to both teams with Group 44 continuing to focus on the American IMSA GTP Championship and TWR on the Group C World Championship. This strategy would give Jaguar two chances at Le Mans glory.
Group 44 had a clear head start as their mid-engined Jaguar XJR-5 was ready late in 1982. The car sported an aluminium monocoque and used the Jaguar V12 engine as a fully stressed member. The car was raced with considerable success in 1983, highlighted with a class win at Road Atlanta. With an eye at Le Mans, a computerized Fuel Injection system was developed over the winter to replace the Weber Carburettors previously used. The XJR-5 raced at Le Mans with factory backing in 1984 and 1985, with a class victory in the second year as a highlight. There was little chance of an overall victory, so Jaguar's focus was now turned to TWR's project.
Other than using a similar engine, TWR's XJR-6 had little in common with the 'American' XJR-5. Tony Southgate was responsible for the design and applied many lessons learned in the abandoned Ford C100 racer. He laid out a carbon fibre monocoque and a highly advanced aerodynamics package with very large ground effects tunnels. It was quite a departure from the norm and would form the mould of all subsequently designed Group C racers. In conjunction with Zytek, TWR developed a Fuel Injection system of their own for the V12 engine. Their goal was to draw as much power from the engine with enough efficiency to meet the strict Group C fuel restrictions. Displacing 6.2 litres, the Naturally Aspirated engine produced around 650 bhp in endurance trim.
Three cars were constructed in 1985, but they did not debut until the end of the season. One of the early problems was the XJR-6's high weight, which also meant the engine could not be run at full power to preserve fuel. Another three cars were built over the winter and prepared for the TWR's first full season in Group C. A victory in the Silverstone 1000 km race was a clear boost to the moral, although Le Mans still proved a bridge too far with all three cars failing to reach the finish. Over the next winter TWR continued their development program and made many (sixty-four to be precise) detail changes to create the XJR-8 (Group 44's latest IMSA GTP car used the XJR-7 moniker).
No doubt the single biggest change was the increase in displacement to 7 litre, boosting the power to 720 bhp. It proved to be the winning formula with the TWR Jaguar team winning eight of the ten races in the World Championship and obviously the championship. Three cars were prepared for Le Mans with special low drag bodies, but it was again not to be for the Jaguar team. The only surviving XJR-8 limped to finish after gearbox problems robbed it from a clear shot at the victory. Porsche won for the fifth year running and as always their strength was in numbers, with the factory team backed up by many privately entered 962s.
As the Group 44 effort faded at the end of 1987, Jaguar commissioned TWR to also campaign their latest XJR-9 in the IMSA GTP in 1988. Again there were only detail changes and one of both the XJR-6 and XJR-8 chassis were upgraded to join the new XJR-9s in the 1988 season. TWR Jaguar again dominated the Word Championship and now also added IMSA's Daytona 24 Hours to the team's tally. Taking a page from Porsche's book, five cars were fielded at Le Mans. This was made possible by IMSA GTP effort and two cars were ran by the team that spent the rest of the season in North America.
During the race, the five Jaguars gradually fought their way to the top until the first car retired with transmission problems eight hours in the race. Eleven hours later a head gasket on the second car failed. All was not lost as Jan Lammers led the race in one of the three surviving examples. Tragedy almost struck when the car suffered from the same transmission problems as the first retiree, but Lammers noticed it in time and left the car in fourth gear to complete the race two minutes ahead of the fastest Porsche. If he had only changed gears once, the transmission would have died and with it the dream of Jaguar's sixth Le Mans win. Lammers took the win together with Andy Wallace and John Dumfries.
After using the same basic chassis design for three years, TWR set about developing two brand new cars for 1989; the XJR-10 and XJR-11 for IMSA and Group C respectively. Both featured a Turbocharged V6 engine of 3 and 3.5 litre displacement. The XJR-10 car was moderately successful, but with one victory the XJR-11 was not a worthy replacement for the XJR-9. Especially in long races, the V6 engine proved fragile and in 1990 the old V12 engine was brought back out for Le Mans. This XJR-12 proved successful once more and scored Jaguar's seventh and final win at Le Mans. After the rules changed again, Jaguar withdrew from racing. TWR used one of the XJR-14 chassis propelled by a Porsche engine to win at Le Mans in 1996 and 1997.
Article by Wouter Melissen, last updated on June 21, 2010
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