Jaguar's supercharged 4.2 litre XKR sports car
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Image Gallery ( 33 images )July 1, 2006 Jaguar yesterday revealed its new supercharged sports car – the Jaguar XKR. Building on the XK that debuted in 2005, the XKR will be available as a Coupe or Convertible. Like the XK model, the new supercharged XKR makes intelligent use of practical, modern technology such as an industry-leading aluminium monocoque structure that results in a light and yet very stiff body. An uprated 420bhp (SAE) supercharged V8 engine and class-leading calibration of a state-of-the-art, six-speed automatic transmission deliver accessible, real-world, high performance of 0-60mph in 4.9 seconds, 50-70mph in just 2.5 seconds and has an (electronically limited) top speed of 155mph. The all-aluminium body construction delivers a lighter, stiffer car, with excellent agility. At 1665kg, the Coupe is 70kg lighter than its predecessor, while the 1715kg Convertible is 100kg lighter than the previous convertible XKR.
With 120bhp (SAE) more power than the normally aspirated 4.2-litre XK and the same strong and stiff aluminium body structure, superb ride and handling is assured. Furthermore, a six-speed automatic transmission with Jaguar Sequential Shift that is regarded as class-leading in terms of speed and refinement ensures Jaguar’s blend of performance and dynamics reaches new heights with the XKR.
“Our aim when engineering the new XKR was to ensure that the car’s characteristics remained in balance despite the significant increase in power over the XK,” explains Jaguar’s chief engineer, Mike Cross. “Working with that as our base, our brief was to create ‘XK plus 30%’ – the ultimate sports GT for the real world.
“We wanted the performance and dynamism you would expect of an XKR but were careful to retain that exceptional blend of sporting luxury that every Jaguar must have and which is so convincingly demonstrated with the XK. The bottom line is that if you like the XK, you’ll absolutely love the new XKR.”
Among the benefits of the increases in power and torque are a Coupe 0-60mph sprint time reduced by 0.3 seconds compared to the previous XKR and acceleration from 50mph to 70mph in just 2.5 seconds.
At the heart of these significant performance improvements is the XKR’s lightweight eight-cylinder engine with an Eaton supercharger. The water-cooled cylinders are arranged in a 90-degree V configuration and the crankshaft is supported by five main bearings. Each of the two cylinder head assemblies incorporates twin camshafts operating four valves per cylinder. One of the reasons for the engine’s impressive output is continuously variable valve timing which helps to deliver a wide spread of torque. The engine uses an Electronic Return-less Fuel System (ERFS) and a three-way catalyst exhaust system for lower emissions.
The increase in power and torque over the outgoing XKR is down to two significant additions to the engine. The air intake has been significantly enhanced thanks to the use of twin air inlets, and a Variable Inlet Camshaft Timing (VICT) system is used for the first time on the XKR. By continuously adjusting the timing of the inlet camshaft on both banks of the V8 depending on the engine speed and load, Jaguar’s engineers have ensured significant improvements in torque, particularly at lower revs.
The VICT system is controlled by Engine Management System (EMS) which receives engine speed, throttle position and oil temperature data from its sensors. The EMS determines the correct inlet camshaft timing by continuously referring to a digital three-dimensional map developed to provide optimum performance. The EMS then transmits the appropriate signals to two solenoids that control the degree of hydraulic force provided to the valve actuators.
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