1991 Jaguar XJR-15

Jaguar's founding chairman, Sir William Lyons, believed that sales success could be achieved through great styling and success in international racing. His C-Type Jaguars, developed from the road-going XK120, were victorious at the 24 Hours of Le Mans in 1951 and 1953. Under pressure to build a new car to continue this record of success, Jaguar introduced the D-Type. The C-Type had used a strong triangulated tubular chassis construction, while the D-TYpe was built around an all-new, riveted aluminum-magnesium alloy monocoque designed by Jaguar's chief designer Malcolm Sayer. Employing techniques learned while in the aviation industry, Sayer was one of the earliest designers to apply the principles of aerodynamics to cars. Compared to the outgoing C-Type, the D-Type was smaller, five inches shorter, and more svelt. Power was sourced from the familiar seven main bearings, 3.4-liter Jaguar engine, which was now canted eight degrees from vertical to clear the low bonnet line.

The potent engine, advanced mechanical components, sophisticated chassis, and slippery coachwork allowed the D-Type to achieve three consecutive victories - from 1955 to 1957 - at La Sarthe. Having won no fewer than five times at Le Mans during the 1950s, the Coventry firm would retire from this ultimate level of competition and would not return to La Sarthe in a Works capacity for three decades.

While absent from Le Mans, Jaguar focused on its road-going vehicles and improving financial stability.

When John Egan became the company's chairman in 1980, he set his sights on returning to the forefront of motorsport, selecting Tom Walkinshaw Racing (TWR) to help with this monumental task. Prior to formalizing their partnership in the form of JaguarSport(incorporated in 1986), TWR campaigned the XJS in the European Touring Car Championship during the early-to-mid 1980s. This success led to the Group C Jaguar/TWR XJR-9 that took the checkered flag at both Le Mans and Daytona in 1988 and 1990.

The Jaguar/TWR XJR-9
TWR, based in the United Kingdom, and Bob Tullis' Group 44 team, based in Virginia, in the United States., were two of Jaguar's most successful privateers during the early 1980s. Group 44 would focus on the IMSA GTP Championship, while TWR concentrated on Group C.

Group 44's Fabcar-designed, mid-engined XJR-5 ready in late 1982 and enjoyed considerable success, including a victory at Road Atlanta. Jaguar contested Le Mans in 1984 and 1985 with the XJR-5, securing a class victory in its second attempt. This success prompted the factory to return to the World Championship as a full Works team that was supported by TWR.

TWR's first full season in Group C was in 1986, and they achieved an overall victory in May at the 1000 KM of Silverstone, fueling their confidence for a successful race at Le Mans the following month. Unfortunately, none of the three cars entered would finish.

Further development over the off-season by TWR resulted in the new XJR-8. In the United States, the Group 44 team's latest IMSA GTP race car was designated the XJR-7. The XJR-8 gave Jaguar and TWR the success it was seeking, dominating the 1987 World Championship and claiming eight outright victories over ten events. For Le Mans, the team entered three cars, but once again, the overall victory remained elusive, with Porsche claiming its fifth consecutive overall victory.

For the 1988 season, Jaguar decided to run a Works team in IMSA and commissioned the new XJR-9. For the second season in a row, Jaguar dominated the World Championship, claiming an overall victory at the 24 Hours of Daytona on their first attempt. For Le Mans, Jaguar entered five cars with the XJR-9 driven by Johnny Dumfries, Jan Lammers, and Andy Wallace claiming the overall victory. For the remainder of the season, Jaguar claimed two more victories at 24-hour endurance events, and, ultimately, the Group C World Championship.

For the past three seasons, the same basic chassis design had been used. For the 1989 season, TWR designed two brand-new turbocharged V-6, the XJR-10 and XJR-11 for the IMSA and Group C Championships, respectively. An updated version of the XJR-9, dubbed the XJR-12, was used solely for long-distance events at Daytona and Sebring. Neither the XJR-10 or XJR-11 achieved the success of the XJR-9.

Beyond the Track
The Jaguar XJR-9 achieved success at the highest levels of competition and was a spiritual descendent of the C- and D-Type of the 1950s. Walkinshaw, recognizing the potential of extending the usefulness of the XJR-9 beyond the track, worked on creating a road-going supercar. In November 1990, JaguarSport officially introduced the ultra-exclsuive, performance-focused XJR-15 (initially designated the R-9R). The first prototype was driven by Mr. Walkinshaw when he returned from France in July 1990. The official launch was early in 1991 at Silverstone. Production was limited to 50 units (53 chassis were eventually built) with production continuing through 1992.

Design and Development
Using the same technology and design philosophy of the XJR-9, the XJR-15 holds the distinction of being the first road-going car made entirely from carbon-fiber. The body was designed by Peter Stevens and power was sourced from a 6.0-liter V12 engine.

As a road-going supercar, the XJR-15 was designed to comply with British construction and use regulations and could be registered by the owner for road-use in the UK. Due to its limited production run, the XJR-15 was never type-approved. Compared to the XJR-9, the cockpit of the XJR-15 was widened and the roof was raised. The engine was a stressed member for the rear-frame and the bottom of the car was flat, similar to Group C configuration. Stopping power was courtesy of a race-spec set of four-piston AP Racing calipers mated to disc brakes residing within center-lock, light alloy OZ wheels.

The naturally aspirated 24-valve Jaguar V12 engine displaced 5,993cc (6.0 liters), had an advanced electronically managed fuel injection system, an advanced 'fly by wire' throttle, and developed 450 horsepower at 6,250 RPM and 569 Nm (420 lb-ft) at 4,500 RPM. The block and heads were built from aluminum alloy, the pistons were forged alloy, and the crankshaft was nitrided forged EN40B steel with Holset harmonic damper. It used a Zytek fuel injection system and electronic engine management, single overhead camshafts per bank of cylinders, two valves per cylinder, seven main bearings, Cosworth pistons, and cast-iron 'wet' cylinder liners. The standard transmission was a TWR unsynchronised six-speed manual transmission, with a five-speed, synchromesh unit being optional.

The suspension was fully independent with non-adjustable Bilstein shock absorbers all round. At the front were wishbones and working push-rods to spring damper units positioned horizontally across the center of the car. In the back was a similar setup to the XJR-9 with vertical coil-springs mounted in units with uprights within the rear wheels.

The wheelbase measured 107 inches, an overall length of 189 inches, a width of 74.8 inches, and a height of 43.3 inches. The bodywork used carbon fiber and Kevlar. The suspension was softer than its racing counterpart and the overall stance was slightly higher as it took full advantage of under-body aerodyanmics.

The exclusivity of the XJR-15 was guaranteed b its price of nearly one million US dollars when new. Of the reported 53 examples built, twenty-seven would leave the factory in 'road' specification, while the others followed directly in the lineage of the preceding XJR race cars and were built especially for the track.

The Jaguar XJR-15 LM
When production of the XJR-15 ended, TWR in collaboration with a British automotive firm XK Engineering developed a limited run of more powerful variants. Dubbed the XJR-15 LM, they were built for a Japanese customer. Power was from a 7.0-liter V12 engine shared with the XJR-9 and developed 700 horsepower. Modifications to the body work included a larger rear wing, a modified engine cover with additional vents, an air intake situated on the roof to aid in cooling the larger engine, and an additional front splitter with air vents in the middle.

It is believed that as many as five examples were produced including three in dark green, one in white, and one in blue.

The 1991 Jaguar Sport Intercontinental Challenge
Sixteen cars built in racing specifications were entered in the Jaguar Intercontinental Challenge, which supported three Formula 1 races in Monaco, Silverstone and Spa-Francorchamps in 1991. Often, the XJR-15s were piloted by professional racing drivers including Derek Warwick, David Brabham, Juan Manuel Fangio II, and Tiff Needell. The winner of the third and final race, Armin Hahne, was awarded a cash prize of US$1 million.

Each of the three races allowed a maximum of sixteen cars. At the first event, Monaco, Armin Hahne, Jim Richards, David Brabham and Davy Jones qualified in the top positions, followed by Bob Wollek, Tiff Needell, John Nielsen, Ian Flux and Juan Manuel Fangio II.

The rolling start of each race was administered by Tom Walkinshaw. After sixteen laps of intense racing, Brabham crossed the finish line seven-tenths of a second ahead of Warwick. Some of the cars received minor damage during the race, but overall, no major incidents occurred.

At the second event, Silverstone, Warwick started from pole with Brabham, Cor Euser, Ian Flux, and Wollek in fifth. Fangio, David Leslie, Hahne, Kenny Acheson and Needell also qualified in the top ten. Following several accidents throughout the field, with eleven of the sixteen entries sustaining some kind of damage, the race was won by Fangio.

The final event was at Spa with the $1 million (USD) purse for the winner. To add even more excitement, Jaguar Sport ran the race for an undisclosed number of laps, telling drivers that the chequered flag would fall after at least six laps. Euser qualified on pole position followed by Brabham, Warwick, Hahne, Percy, Will Hoy, Wollek, Leslie, Thierry Tassin and Flux. On lap eleven, when the chequered flag fell, it was Hahne in the lead.

by Daniel Vaughan | Apr 2023