The first prototype built was the Jaguar XJR-5. This car designed to run in the IMSA Series GTP Championship had a V12 engine, aluminum monocoque structure and great attention to aerodynamic development. The XJR-5 debuted on American tracks in August 1982. Drivers Bob Tullius and Bill Adam managed to climb the podium in their first race at Road Atlanta, behind two Porsche 935.
Bob Tullius owned his own team, “Group 44”, and had the support of Jaguar part the technical development of the car. In 1983 Tullius and Adam demonstrated the potential of the Jaguar, winning 4 races and finishing third in the GTP Brand Championship. Third place was especially meritorious, as the other manufacturers had many more cars on the track.
By 1984 things got complicated at IMSA. The success of the March 84G Chevrolet and the successful debut of the Porsche 962 overshadowed the performance of the XJR-5, which achieved only one victory. In the same year Tullius took his Jaguar to the 24 Hours of Le Mans, although both left.
The 1985 season was dominated by Porsche. The Jaguar XJR-5 achieved only one win and a few podium finals to place in a distant second place at the end.
The development of the XJR-6 included a carbon fiber monocoque, great aerodynamic development with huge air tunnels to generate ground effect, and an electronic fuel injection system specially designed for the 6,200 cm3 V12. This engine delivered a power of 650 hp. The counter of the car was still its heavy weight, which increased consumption.
The brand-new Jaguar XJR-6 of Group C debuted at the 1000 Km of Mosport (Canada) in 1985 with an excellent third place, among the unbeatable Porsche 962 and 956 . In 1986 the TWR team performed in all races of Group C obtaining a win and 4 other podiums. At the end of the championship the TWR Jaguar team came third in the table, just five points from the leader.
The TWR team continued to develop improvements for the Jaguar prototype to be used during 1987 in Group C. With more than 60 modifications, the new XJR-8 prototype incorporated the same V12 but now 7,000 cm3, reaching a maximum power of 720 hp.
The new engine was a key factor for Jaguar's success. Jaguar dominated in 1987, winning 8 out of 10 races and winning the FIA Championship. Although he still had the feeling of not being able to win at Le Mans, even having prepared a car specially for that circuit.
Basically, the XJR-8 with some differences was also used in IMSA GTP, although the car of the “Group 44” team was named Jaguar XJR-7. 1987 would be the last season of the Group 44 team in IMSA, since the TWR would subsequently be presented in both categories.
In 1988 Jaguar found a tough rival in the thriving Sauber Mercedesteam, which won 5 competitions. Still, Jaguar scored 6 wins and outperformed Sauber. TWR Jaguar was crowned champion for the second consecutive year in Pool C.
By 1989 all the land won was lost. Jaguar couldn't even win a race. The XJR-9 was completely displaced by the Sauber Mercedes C9, who won 7 out of 8 races.
The TWR Jaguar XJR-9 also stood out at IMSA, winning the Daytona 24 Hours in 1988 and occupying a good third place at the end of the competition. In 1989 he improved overall performance, but was defeated in the championship by Nissan prototypes.
While the XJR-9 faced both championships, TWR began the simultaneous development of a new prototype. The new car would have two versions, XJR-10 for IMSA and Jaguar XJR-11 for FIA. Both incorporated new V6 Turbo engines of 3 and 3.5 liters of displacement respectively.
The first tests of XJR-11 in 1989 were not bad. The following year he achieved a victory at Silverstone, but he was not reliable enough to replace the XJR-9. The XJR-11 had improved, but not enough. TWR then decided to design new cars with the old V12 engines specially prepared for the 24 Hours of Le Mans. These prototypes were named Jaguar XJR-12.
The Jaguar XJR-12 participated in the IMSA series, achieving an excellent victory in the Daytona 24 Hours 1990. The rest of that season was faced with the XJR-10, who won 2 races. Once again, at the end of the Championship Nissan took advantage by moving Jaguar to second place.
Subsequent regulatory changes in Group C forced TWR to set aside turbo engines. The Jaguar XJR-12 brought to Le Mans 1991 then carried the old V12 engine. Except at Le Mans, the 1991 FIA Championship was played with the Jaguar XJR-14, equipped with a new 3,500 cm3 engine V8 Cosworth.
The famous Silk Cut Jaguar XJR-14 regained the tip level. With new rivals like Peugeot and Mazda , the FIA Championship was held between six teams with real opportunities. Jaguar and TWR quickly reacted to the new regulations and outperformed their rivals. The XJR-14 won three competitions and its third Group C Championship in less than 7 years.
Changes to regulations discouraged TWR from continuing its developments, leaving Group C competences and only dedicated to the GTP category in IMSA.
In 1992 the TWR team participated in IMSA with the Jaguar XJR-12D and XJR-14. The first took a second place at Daytona (although he won his GTP class) and a fourth at Sebring. The XJR-14 won two victories and finals on the podium, placing third in the GTP Championship.
In 1993 TWR participated unsuccessfully in Daytona and immediately Jaguar decided to withdraw from IMSA competitions. As a background, it is noteworthy that the TWR team won the 24 Hours of Le Mans in 1996 and 1997 using the chassis of the Jaguar XJR-14 but carrying an updated Porsche engine.
© Adrián Blanco 2007 - No full or partial reproduction of text and/or images without explicit written consent of the author. —
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