Opulence Overkill: Bentley Arnage T's 2007 Upgrade

By Motoring Channel Staff - 31/Aug/2006

Crewe, England — Like a luxury steamroller fitted with a chesterfield couch, air conditioning and satellite navigation, the new Arnage T from Bentley is an impossibly large and eerily heavy vehicle that has just been given a surge in power.

Tipping the scales at 2585kg (5699 lbs) and measuring 5.4 metres in length, you don't want to get in the way of this vehicle when it reaches its top speed, as all this mass is pushed forward by a huge 6.7-litre V8 engine that makes use of twin turbochargers to boost mid torque to a stunning 1000Nm.

This 14 per cent increase in torque and almost 2.6 tonne kerb weight fails to stymie the vehicle's performance: it's able to shift it's considerable bulk from zero to 100km/h in about 5.4 seconds. And that's what Bentley is crowing about in the 2007 model - performance.

While the Bentley brand has always prided itself on fitting large 8-cylinder engines into its vehicle range, for the most part they have been excellent luxury cruisers and limousines. But with advances made in the Arnage's frame and chassis, Bentley is saying that the increased power seen in this new 2007 model (due on sale in September in some markets) is easily controlled.

"Two years ago we introduced major upgrades to the Arnage's chassis, steering and brakes," mentioned Dr. Ulrich Eichhorn, Member of the Board for engineering. "Those improvements meant the car could easily handle a significant increase in power and torque, so work began on this important powertrain programme."

The 6761cc V8 engine is the centrepiece of the new 2007 Model Year Arnage development programme, whose fundamental design has served Bentley models for nearly five decades. An extensive re-engineering programme was created to provide the Arnage T specification with 373kW (500bhp) and 1000Nm of torque, taking it's top speed from 270km/h to 288km/h (179mph), which is breathtakingly fast for something so large and with little attention paid to aerodynamics.

Bentley explains that during the 1950s, when the first V8 engine was being built, the design brief was a very forward thinking: the V8 architecture included all-aluminium construction, a five main-bearing crankshaft and a well-supported camshaft.

"People might raise an eyebrow when they are told that the V8 engine in their 2007 Model Year Arnage was first used by Bentley in 1959," said Brian Gush, the man in charge of overseeing powertrain and chassis operations at Bentley Motors. "But the reality is the basic design was so good that we have been able to continually improve it for nearly 50 years.

"One of the reasons the engine has evolved so successfully is the position of the exhaust valves, high in the cylinder head, originally designed for rapid heat dissipation to help engine cooling. Decades later it meant that we could heat the catalytic converter due to the short path from valves to catalysts, which benefits exhaust emissions. This is just one of the reasons why this brilliant engine lives on today."

Where the first generation 6.2-litre V8 engines produced about 200 horsepower or 149kW, the new 2007 Model Year 6.7-litre V8 has more than twice that output. Bentley says that it was the introduction of turbocharging and intercooling in the early 1980s that saw step-change increases in the V8's performance, and the latest engine programme is no different. The newest engine's power increases come primarily from a pair new low-inertia turbochargers that operate with far greater efficiency at lower engine speeds, reaching maximum turbine speed in half the time of the previous unit. Bentley claims this reduces turbo lag while providing a prodigious wave of torque at any engine speed.

As well as the increase in the force-fed V8's power output, which the company insists is the most powerful version of Bentley's legendary V8 engine ever built at the company's headquarters in Crewe, the British-based prestige car maker has added a new 6-speed automatic gearbox to its range-topping super saloon. A high torque version of the German-built 6-speed ZF automatic transmission was chosen for the new Arnage T (also seen in BMW, Audi and Ford vehicles).

"The new ZF gearbox gives us a different dimension in transmission control. Our main objective was to get the engine and transmission working together enabling us to transmit every ounce of power," said Dr. Ulrich Eichhorn, Member of the Board, Engineering. 

"Using the lock-up in all gears eliminates what we call the ‘rubber-band’ effect – the surge of engine speed without a corresponding acceleration of the car – and gives much more immediate connection of throttle input to road speed," added Dr. Eichhorn.

However, Bentley is quick to agree that increases in power and torque are of little benefit unless the chassis is able to cope with it. A comprehensive chassis tuning programme was instigated alongside the powertrain updates to ensure the Arnage's chassis comfortably handles the additional performance. One thousand Newton metres of torque puts significant stresses on more than just the gearbox and drive shaft, and the suspension has been appropriately revised. Bentley's software engineers also made changes to the ESP logic system and traction control to allow more spirited handling without any reduction in stability or safety.

"We don't believe in creating power and then taking it away," stated Brian Gush. "This new system allows the driver a lot more freedom to feel where the traction limit is without ever getting into trouble. The traction control is much more progressive and proportional – you can drift the car with some wheelspin but it never lets you get in any trouble. It is a calibration which keeps the spirited driver in mind."

Bentley has also added a 'Sport' mode. This comes into play via a sport button on the dashboard, giving the suspension an even more responsive feel, allowing drivers to attack corners with more confidence, while being able to switch it off when the time calls for relaxed cruising.

As well as the vehicle's improved handling dynamics and 288km/h performance, the 2007 Bentley Arnage T also gets benefits from exterior and interior design highlights. "The revisions we made to the Arnage series two years ago gave the range exactly the sort of contemporary yet authentic Bentley feel that it needed," explained the exterior design director Raul Pires. "Now with big increases in power and performance we wanted to add some subtle design cues to reflect the differences between the Arnage models."

The sporting intent of the Arnage T is enhanced by a new dark finish to its front radiator and bumper grilles. Bentley ‘B’ badges have been applied to the D-pillars on all models and to highlight the superb feat of engineering beneath the Arnage's bonnet, a newly styled engine bay leaves no doubt as to the potency of the car. A black crackle finish has been applied to the Arnage T's inlet manifold, while every model displays an embossed Bentley logo on the turbocharger plenum chambers and new ‘6¾ LITRE TWIN TURBO’ engine plaques.

The optional extras list reads like that of a sports car, which 19-inch five-spoke ‘Blade’ sports wheels for the Arnage T, and available across the new 2007 Arnage range is the famous winged ‘B’ mascot. The iconic mascot – which can retract neatly into the grille surround to avoid being pilfered or damaged – was originally designed by motoring artist F. Gordon Crosby and first used on the 1930 Bentley 8 Litre.

Inside the luxury limousine are subtle design updates that include a new hide-trimmed gearlever with chrome gearlever bezel, and what the company calls a Thin Film Technology driver information panel to display more comprehensive and clearly accessible information. Bentley has revealed that every Arnage now has a tyre pressure monitoring System, rSAP Bluetooth integrated telephone system and improved driver ergonomics as standard. Additionally, new wheel, exterior paint colour and interior trim options are available.

The new 2007 Model Year Bentley Arnage range will go on sale from September 2006. Stuart McCullough, the head of Bentley's sales and marketing team, put the new Arnage in perspective: "The 2007 Model Year Arnage range is clear evidence of our intent to ensure Bentley's flagship model remains at the forefront of technology and delivers the performance, refinement and luxury that every Bentley customer demands." 

In other words, Mr McCullough is saying Bentley is king, and Rolls Royce is not. Expect return fire from RR very soon with a number of updated models, including a 12-cylinder convertible.