After Jaguar's withdrawal, it was up to privateers to defend the honours of the leaping cat. One of the premier Jaguar privateers was Bob Tullius, whose Group 44 racing campaigned first campaigned a Jaguar in 1974. He won the Sports Car Club of America (SCCA) B production category with a mildly modified V12 engined E-Type. Over the years he kept on competing V12 Jaguars in the SCCA championships and in Trans Am. When the new IMSA GTP class was formed, Tullius decided to construct a prototype racer around the V12 he knew so well.
At LeMans there was a class for IMSA GTP cars, so this could end up as Jaguar's return to the French track. That foresight sparked interested in Coventry and with factory backing work was started in the Winchester, Virginia headquarters of Group 44 racing, early in 1981. The prototype would be aptly dubbed XJR 5; Group 44's previous four cars were XJR 1 - 4.
Hired as designer was Lee Dykstra, whose Special Chassis Inc had designed a successful ground effects racer in 1980. Dykstra decided to use the long and relatively heavy V12 engine as stressed member of chassis. The engine was bolted directly on the aluminum monocoque, supported by four stiffening struts bolted on the firewall. The slim design was completed by attaching the rear suspesion on the transaxle, leaving plenty of space for underbody aerodynamics.
Pioneered by Lotus in the late 1970s, ground effects aimed at reducing the air pressure under the car. Grip was created by the low air-pressure 'sucking' the car to the ground. To create ground effects, the underbody of the car was shaped like the top half of an airplane wing. The XJR 5's slim monocoque chassis allowed for large, clean 'wing' surfaces on each side of the engine. After many windtunnel tests of quarter scale models in the Williams rolling road windtunnel, two underbodies were constructed. A low drag, low downforce version for high speed tracks like LeMans and Daytona and a high downforce one for slower tracks.
In TransAm spec, the V12 engine was fed by six Weber carburetors, this setup was carried through on the GTP car. In the first full season of racing the Webers were still used, but as a LeMans entry came closer work was started on a computer controlled fuel injection system. Fuel efficiency was vital at LeMans, where the quantity of fuel available was restricted. First tested in December 1983, the Lucas Micos system provided both a better throttle response and a higher mileage.
Teaming up with co-driver Bill Adam, Tullius debuted the XJR-5 in the 1982 Road America round of the GTP championship. The result was better than anyone could have hoped for, with a third place overall and a win in the GTP class. Small problems in the next few races prevented the XJR-5s to copy the Road America performance. Jaguar scored the first victory in the 1983 Road Atlanta 500km race, with Tullius and Adam at the wheel. In the next couple of seasons, more victories were scored, but the team was never a contender for the championship against the much more powerful turbo-charged Porsches, Nissans and Toyotas.
Impressed by Group 44's performance in 1983, Jaguar was growing more comfortable in supporting a LeMans return, especially now that the V12s were equipped with the Micos system. After a series of successful long distance tests in the first months of 1984, Jaguar was convinced and agreed to back Group 44's LeMans entry. The XJR-5 was the first Jaguar to compete at Le Mans in 22 years and the first factory backed Jaguar to enter since the glory days of the 1950s. Although no match on speed for the turbocharged Lancias and Porsches, the two entered XJR-5s were running in sixth and seventh when they [the Lancias and Porsches] retired around the 14th hour of the race. The XJR-5 returned to Le Mans once more and claimed 13th overall and a win in the GTP class.
Although successful, Group 44 lost their factory backing to Tom Walkinshaw's TWR. Tullius did construct a replacement for the XJR-5, which took another three victories, but he did not return to Le Mans after the 1985 season. TWR's bid at Le Mans proved more successful, with victories in 1988 and 1990.
The XJR-5 pictured is a GTP version, taking part in the Group C revival race, which was part of the 2003 RMU Classic at the Spa Franchorchamps track.
- from ultimatecarpage.com
The XJR-5 has a 6.0 liter V-12 producing 650 hp at 7,500 rpm and 480 lb-ft of torque at 6,000 rpm. It has a top speed of 217 mph.
"The 1950s at Le Mans could be described as the 'Jaguar-Years' with the marque winning five times using the C-Type and D-Type. Jaguar wanted to relive their successes at the most grueling endurance in the 1980s. They teamed up with TWR, run by Tom Walkinshaw who raced with Jaguars since the 1970s.
Their first jointly developed Group C racer was the XJR-6 introduced late in 1985. It was powered by an enlarged and extensively modified version of Jaguar's road going V12 engine. This engine itself was a direct development of the engine used in Jaguar's last prototype racer of the 1960s, the XJ13. The XJR-6 proved fast but lacked the reliability to really threaten the German Porsches.
For the 1987 season TWR/Jaguar revised the XJR-6 and renamed it XJR-8. The biggest change was found in the engine bay, it now housed a 7 litre long stroke V12 engine. The XJR-8 also incorporated revised front and rear suspension.
The new package proved a winner straight out of box and it dominated the season's sprint races. The team scored eight victories and took the constructor's championship with almost twice as much points as its nearest competitor. Raul Boesel chlinched the driver's title.
Le Mans however was a different story, the XJR-8 LMs were fast but let down by many small mechanical problems. Only one of the three cars did manage to finish but many laps down from the winning Porsches.
The XJR-8 seen above is fitted with the very successful 'sprint' style bodywork."
- from ultimatecarpage.com
The XJR-8 has a 7.0 V-12 with 720 hp at 7,000 rpm and 605 lb-ft of torque at 5,250 rpm.
"After an absence of almost three decades Jaguar returned to Le Mans in the 1980s with their V12 engined sportscars. The car was designed and run by Tom Walkinshaw's TWR who had campaigned a modified XJS in the 1970s. In 1988, over 30 years after their last victory on Le Mans, the Jaguar team finished first again in the grueling 24 hours race. The Lammers, Dumfries and Wallace team beat a whole pack of Porsche 962s and ended the iron grasp the Stutgart based firm had on the event in the previous five years. With an average speed of 211.6 km/h the XJR-9 covered a distance of 5332.7 km."
- from ultimatecarpage.com
The XJR-9 LM, shown below, has a 7.0 liter V-12 producing 750 hp at 7,200 rpm and 611 lb-ft of torque at 5,500 rpm. It has a top speed of 245 mph.
"Jaguar roared for a seventh and final time at LeMans in 1990. The car used was the final evolution of the V12 engined TWR designed XJR-6. Most of its competitors at LeMans ran turbocharged engines, but the TWR kept on using the proven naturally aspirated V12 engine.
Early in the race the turbo Nissans and Porsches fought for the lead with the four Jaguars keeping within striking distance. Over the night the turbocharged cars paid for their early speed and one by one started to retire, in the final hour the last Porsche blew up. This retirement saw the #3 and #2 Jaguar move up to first and second respectively.
The XJR-12 featured is the actual LeMans winner and is still owned by team manager Tom Walkinshaw. It is seen here at the 2002 Goodwood festival of speed."
- from ultimatecarpage.com
The XJR-12 has a 7.0 liter V-12 producing 730 hp at 7,000 rpm and 579 lb-ft of torque at 5,500 rpm. It has a top speed of 229 mph.
Eddie Cheever and Raul Boesel drove this Jaguar XJR-8 to victory. From 1986 to 1988, while still driving in Formula One, Cheever won ten sports car races for Jaguar.
