The Jaguar Sport XJR-15 is a two-seater sports car of which a limited number were produced by JaguarSport, a subsidiary of Jaguar and Tom Walkinshaw Racing, between 1990 and 1992. Only 50 were planned (although 53 chassis were eventually made), each selling for £500,000.
The chassis was mechanically based on the Le Mans-winning XJR-9, designed by Tony Southgate. The body of the XJR-15 was designed by Peter Stevens, who went on to co-design the McLaren F1. The car competed in a single-make racing series called the Jaguar Intercontinental Challenge, which supported three Formula 1 races (Monaco, Silverstone and Spa) in 1991. The XJR-15 was the world's first road-car made entirely from carbon-fibre.
History
Tom Walkinshaw conceived the concept in 1988 after seeing the XJ220 concept at the British Motor Show. Following Jaguar's success at Le Mans, he enlisted Peter Stevens to develop a road-going version of the XJR-9, originally designated the R-9R. A number of wealthy racing enthusiasts were keen to own such a car and pressed Walkinshaw into manufacturing a 'road going racer'. This car was originally intended to be a better alternative to the XJ220. Original owners included Derek Warwick, Bob Wollek, Vern Schuppan, Matt Aitken, Andy Evans and the Sultan of Brunei.
In order to adapt the XJR-9 for road use, Stevens made a number of modifications to increase space and improve access. "Taking the race car as a base, we widened the cockpit by and raised the roof by to allow more headroom", he said when interviewed in 1991.Jaguar World, Spring 1991 "The scale model was ready by Easter 1989, from there we went to clay... which was finished by October (1989). The first prototype was held up by Le Mans preparations but it was ready for Tom (Walkinshaw) to drive when he came back from France in July 1990".
TWR explicitly developed the XJR-15 as a road-going racing car, in the mould of the Jaguar C and D types, the Ford GT40 and the Ferrari 250 GTO. As such, the car complied with British construction and use regulations and could be registered by the owner for road-use in the UK, although with such a limited production run, the car was never type-approved.
The car's production was announced in a press release on 15 November 1990 with an official launch at Silverstone early in 1991. The XJR-15 was built by JaguarSport in Bloxham, Oxfordshire, (a subsidiary of TWR; it was a joint venture between Jaguar Cars and TWR to produce high performance sports cars) England from 1990 to 1992 and had no official involvement from Jaguar itself.
Design and reception
The XJR-15 is powered by a , naturally aspirated 24-valve Jaguar V12 engine. The engine features an advanced electronically managed fuel injection system with a very advanced (for its time) 'fly by wire' throttle. The standard transmission is a TWR unsynchronised six-speed manual transmission while a five-speed, synchromesh transmission was also available as an optional extra.
The XJR-15's chassis and bodywork are composed of carbon fibre and Kevlar (it was the first road-going car built entirely of carbon and Kevlar composites,World Sports Cars, January 1992 before the McLaren F1 used similar construction techniques in 1992). The overall proportions differed from the XJR-9, with the XJR-15 being 480 cm long, 190 cm wide and 110 cm tall. The final weight amounted to be .
A fully independent suspension was used, with non-adjustable Bilstein shock absorbers all round. Front suspension consists of wide-based wishbones and working push-rods to spring damper units mounted horizontally across the centre of the car. The car retains the rear suspension unit from the XJR-9 with vertical coil-springs mounted in units with uprights within the rear wheels, allowing for the maximum possible venturi tunnels. The engine forms a stressed member for the rear-frame. The bottom of the car is completely flat, in line with Group C practice.
The brakes are steel disc units with AP four-piston callipers.
The XJR-15 has a time of 3.9 seconds and a gearing limited top speed of .
The ride height was somewhat higher than required to take full advantage of under-body aerodynamics due to the road going nature of the car. Additionally, the suspension was softer than would be found on the XJR-9 racer and - in a last-minute deal - Tom Walkinshaw switched tyre suppliers from Goodyear to Bridgestone just before the race series started. When interviewed by Autosport"Autosport, September 1, 2011" in 2011, Ian Flux recalled: "The worst thing was that Tom had done a deal with Bridgestone. At first, it was going to be on road tyres, but then they changed to slicks and wets. The fronts weren't a problem, but they didn't have moulds for the rears, so used F40 moulds instead. They went off very quickly and it was hard to judge how hard to push."
As Tiff Needell, who road-tested a development car at Silverstone early in 1991, put it: "the result is oversteer". However, once accustomed to the characteristics, he went on: "Through the very tight chicane, the XJR-15 showed excellent change of direction and I was able to pick up power early for the long right hander leading up to Beckett's. This gradually became a long right-hand power slide as my confidence increased."
As a road-car, the suspension was more softly set-up and with the right tyres, testers were unanimous in their praise. Ian Kuah, writing in World Sports Cars in 1992:"World Sports Cars, January 1992" "Considering its racing pedigree, ride quality is pretty good - at low speeds, better than a Ferrari 348...Levels of grip are far beyond those transgressed by any sane man, except perhaps when exiting a tight corner in a low gear when the sheer grunt pushing you through can persuade the huge Bridgestones to relinquish some grip. Seat of the pants feel and communication is terrific and the steering nicely weighted so that smooth inputs are easy. When it comes to stopping, the huge AP Racing brakes - with softer pads for road use - wash off speed with steely determination."
Ron Grable, the racing driver, writing in Motor Trend in May 1992:"Motor Trend, May 1992" "As the engine sprang into a muted rumbling idle, it was impossible to keep from grinning. Easing the unsynchronised six-speed into gear, I accelerated onto the straight. Many race cars are diabolical to get moving...not so the Jag, the smooth V-12 pulled cleanly away, nearly as docile as a street-car. On the track, the XJR-15 is a truly wonderful ride, the perfect compromise between racing and street. You can say the savage edge of a pure race car has been softened slightly, or conversely, that it's the best handling street car you can imagine. Being 100% composite, it's so light that every aspect of performance is enhanced. Relatively low spring and roll rates are enough to keep it stable in pitch and roll, as well as deliver a high level of ride compliance. The brakes are phenomenal and the acceleration fierce. And always, there's that V-12, a medley of mechanical noises superimposed over the raucous rise and fall of the exhaust."
The XJR-15 offers little in the way of practicality. Entry to the car, over a wide sill, requires the driver to step onto the driving seat. The gear-lever is mounted on the right-hand side of the driver (all cars are right-hand-drive), while the driver and passenger seat are extremely close together - almost central in the car. Due to minimal sound insulation, an in-car head-set system is fitted. There is no storage space in the car due to its racecar-like nature. However, considering the purpose for which it was intended, the interior was highly praised in contemporary automotive press publications. Ron Grable wrote: "Aesthetically, the XJR-15's interior is breathtaking. Expanses of shiny black carbon fibre woven with yellow Kevlar are everywhere, all fitting together with meticulous precision. Instrumentation is detailed and legibly analogue. The shift lever is less than from the small steering wheel, and the motion between gears is almost imperceptible. The reclined seating position provides excellent forward visibility - over the top of the instrument panel you see only racetrack."
Technical specifications Engine Type: Naturally aspirated 60° V12 Construction: aluminium-alloy block and heads, forged-alloy pistons, nitrided forged EN40B steel crankshaft with Holset harmonic damper, seven main bearings, cast-iron 'wet' cylinder liners, Cosworth pistons Bore X Stroke: Valvetrain: Operated by Single OverHead Camshaft per bank of cylinders, 2 valves per cylinder Fuel System: Zytek fuel injection and electronic engine management Displacement: Compression ratio: 11.0:1 Max. Power: at 6,250 rpm Specific output: per litre Max. Torque: at 4,500 rpm Engine weight: including clutch and accessories Transmission The following data is for the TWR 5-speed manual (with synchromesh) Gear Ratio 1st: 3.00 :1 Gear Ratio 2nd: 2.13 :1 Gear Ratio 3rd: 1.66 :1 Gear Ratio 4th: 1.38 :1 Gear Ratio 5th: 1.18 :1 Gear Ratio 6th: 0.91 :1 Final drive ratio: 2.90 :1 AP carbon triple-plate clutch Body Body/Frame type: carbon fibre Body/Chassis details: Carbon fibre and Kevlar composite construction monocoque chassis with engine used as rear suspension load bearer; lightweight composite and carbon fibre reinforced body with under-surface adopting ground-effect, venturi channels' to the rear and regulation flat floor (race trim) Coefficient of Drag: 0.30 Weight distribution: 48% front, 52% rear Wheels/tyres: 17-inch OZ forged alloy wheels (9.5 front/13 rear), Pirelli P Zero tyres. Performance 0–: 3.2 seconds Top speed: Power to weight ratio: /tonne
Racing history
According to a press release by Jaguar Sport, a limited number of XJR-15s were built specifically to compete in the 1991 Jaguar Sport Intercontinental Challenge; a three-race competition held throughout the year as a support event for the 1991 Formula One Grand Prix at Monaco, Silverstone, and Spa-Francorchamps.
Sixteen cars built in racing specifications were entered in each of the events. The winner of the third and final race, Armin Hahne, was awarded a cash prize of US$1 million.
Having parted with nearly US$1m for their cars, most XJR-15 owners wanting to participate in the Intercontinental Challenge got professional drivers to drive the cars. Preparation and maintenance by Jaguar Sport was included in the purchase price of the race cars. At stake for the winners of the first two rounds were a pair of Jaguar XJR-S road cars whilst at the Spa finale there was a US$1m winner-takes-all prize fund.
A maximum of 16 grid slots were available for each event and all three were fully subscribed. Derek Warwick emerged on top of the timesheets in qualifying followed by Armin Hahne, Jim Richards, David Brabham and Davy Jones. Rounding out the top ten were Bob Wollek, Tiff Needell, John Nielsen, Ian Flux and Juan Manuel Fangio II.
Each race kicked off with a rolling start administered by Tom Walkinshaw and the charge into Ste Devote saw Warwick and Hahne touch several times before Warwick emerged in front. On lap two, John Nielsen ran wide at Tabac and thumped the barriers on both sides of the track before Hahne lost it entering the swimming pool on lap three, luckily emerging unscathed. This allowed Warwick to open up a four-second gap from Brabham, Jones and Fangio before losing it all after locking up into the swimming pool. The Englishman eventually finished seven tenths of a second ahead of Brabham after 16 laps of hard racing.