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Revision as of 03:25, 15 October 2007 by Mulsannescorner (talk | contribs) (→Engine)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)The Jaguar XJR-14 was a Sports-prototype racing car introduced for the 1991 World Sportscar Championship season.
Introduction
The 1991 season marked the introduction of the FIA’s new, and controversial, 3.5 litre formula which replaced the highly successful Group C category that had been used in the World Sportscar Championship since 1982. However, due to a small number of entries in the new 3.5 litre formula heavily penalised Group C cars were allowed participate in the newly created C2 category for the 1991 season but Jaguar participated in the new formula.
To comply with the new regulations Jaguar produced an all-new car, the XJR-14. It was designed by John Piper under the design direction of Ross Brawn and was built by Tom Walkinshaw Racing (TWR). In the past, TWR's Jaguars had been designed under the direction of Tony Southgate, while Brawn worked with a large design staff (12 according to John Piper).
Engine
The primary feature of the new regulations centred around 3.5 litre naturally-aspirated engines. Although the XJR-14's predecessor, the XJR-11, used a twin turbo charged 3.5 litre engine derived from the Metro 6R4-derived JV6 engine, in order to comply with the new rules the two turbochargers would need to be removed. Naturally this wasn't a realistic option, nor was it ever considered, given the design compromises.
But given the Jaguar-Ford connnection, it was a decided to utilize the 3.5 liter Ford HB V8 Formula One powerplant. Most notably used by the Benetton Formula One team, but now badged as a Jaguar, the Ford HB was detuned to about 11,500 rpm (compared to about 13,000 rpm) and aimed to produce slightly less power (about Template:Auto bhp vs. around 700 bhp) with aims at enhanced reliability.
Design
Design wise the XJR-14 looked unlike any of the previous Group C sports-prototypes. Despite racing at other circuits previous sport-prototypes were primarily designed for Le Mans` Circuit de la Sarthe (where top speed was key) which meant that these cars had low drag, low downforce designs which, coupled with their top-end power and straight-line acceleration, led to speeds well in excess of Template:Auto mph on the famous Mulsanne Straight.
However, following the redesign of the Circuit de la Sarthe in 1990 the low drag, top-end power, straight-line acceleration and top-speed characteristics of previous sports-prototypes were no longer required. The XJR-14 now focussed more on downforce and featured a full width double-decker rear wing and a front wing between the lights. This led to the car having a lower top speed than Group C cars and, coupled to the characteristics of the 3.5 litre engine, less accelerative above 150-170 mph. However, the lower kerb weight of Template:Auto kg and the increased downforce meant that the XJR-14 was a lot faster in corners. The overall effect of the new design meant that the XJR-14 was as fast as a contemporary Formula One car around circuits used by the Grand Prix fraternity, though had the XJR-14 competed at the Circuit de la Sarthe before 1990 it would have come 2nd best against a Group C car.
Race results
In the early part of the 1991 World Sportscar Championship season the XJR-14 was in a league of its own, totally outclassing its rivals and in particular the Peugeot 905 and Mercedes-Benz C291. Only the opening race went Peugeot's way, but that was seen more as luck than the 905's ability. The fact that Jaguar already had race proven engine certainly helped the team’s cause but the rest of the car was so much more superior than its rivals.
It wasn't until midway through the season that the Jaguar met its match through Peugeot's new 905B. This meant a hard fight with the new and quickly improving Peugeot squad for the rest of the season, but Jaguar was able to hold on and secure the manufacturers title with 3 victories.
At the 1991 24 Hours of Le Mans, Jaguar initially entered two XJR-14s but later decided that the XJR-14 would not be capable of finishing the distance due to unknowns in the development of the Cosworth HB to last 24 hours. Jaguar instead decided to enter three older XJR-12s which entered in the C2 class. Although the XJR-12s did not manage to win, Jaguar's decision not to run the untested XJR-14 was vindicated by the fact that Peugeot's 905 didn’t finish the race although Peugeot did not have an older Group C car to fall back on, while Mercedes also withdrew its C291 in favour of its older C11 models.
After 1991, Jaguar decided not to continue in Group C, believing that they had spent enough time in Group C and the instability of rules recently in the World Sportscar Championship. Jaguar decided to take the XJR-14 to the United States for the IMSA Camel GTP championship. However, without a major upgrade, the XJR-14 was unable to beat the latest challengers from Toyota and Nissan, forced to finish third in the championship with only two victories. Jaguar had to go through three chassis in the series after two, #591 and #791, were written off in separate accidents.
Derivatives
Meanwhile, TWR had reached an agreement to supply more XJR-14 chassis to Mazda, minus the Cosworth V8s but installed with Mazda-badged Judd V10s for the World Sportscar Championship. Mazda would rebadge the XJR-14s as MXR-01s. The MXR-01 was essentially a productionsed XJR-14 and as there had been no ongoing development they ended up not being particularly competitive, scoring no wins and finishing third in the championship.
Several years later, TWR would resurrect XJR-14 chassis #691, which had competed in IMSA Camel GTP, for the development of a new prototype for Porsche. They renamed the car the TWR-Porsche WSC-95. Its most significant feature was that it had the roof removed, turning it into an open cockpit prototype to run under the then-new LMP regulations. The WSC-95 would carry a Porsche 3.0L turbocharged Flat-6. After chassis #691 was modified, TWR built a second WSC-95 from scratch. In both the 1996 and 1997 24 Hours of Le Mans, the TWR-Porsches were able to take the overall win. Former XJR-14 chassis #691 would eventually end up in the Joest museum, the team which took the WSC-95 to victory in both years.