Bentley Arnage gains power

500bhp from venerable 6.75-litre V8

Bentley Arnage T get more grunt

Next year's Bentley Arnage will gain significant power increases -- well, you'd hardly expect less would you?

According to Bentley, it's introducing "a major programme of powertrain and chassis enhancements for the 2007 model year. The Arnage's 6.75-litre V8 engine now develops up to 500bhp and is mated to a six-speed automatic transmission. There'll also be subtle exterior, interior and under-bonnet design cues.

Key to this performance increase is the most powerful version of Bentley's V8 engine ever built at the company's headquarters in Crewe. In the performance-oriented Arnage T model, the revised twin-turbocharged V8 engine produces 500bhp and 737lb-ft of torque (that's 1,000Nm in new money) - an 11 per cent increase in power and a 14 percent increase in torque over the outgoing model. It's twinned with the latest six-speed ZF automatic transmission. In the Arnage R and RL models the new engine is boosted from 400 to 450bhp, while torque climbs from 616lb-ft to 645lb-ft.

The 500bhp Arnage T is aimed at being a true driver's car with higher performance and a more rewarding driving experience. The 450bhp Arnage R gets more interior updates, while the long-wheelbase RL gets an increased power output and major improvements to the rear passenger cabin.

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

The 2007 Arnage also gets safety, interior and design improvements, including a tyre pressure monitoring system, Bluetooth integrated telephone system and improved driver ergonomics. Additionally, new wheel, exterior paint colour and interior trim options are available, as well as an optional retractable 'Flying B' bonnet mascot.

"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," said marketing man Stuart McCullough.

The new 2007 Model Year Bentley Arnage range will go on sale from September 2006.

Overview

Uprated 6.75-litre twin-turbocharged V8 engine in Arnage T produces 500bhp and 1000Nm torque, thanks to new low inertia turbochargers and roller tappet system.
Arnage R and RL models uprated to 450bhp and 875Nm of torque.
Latest six-speed ZF automatic transmission with sophisticated locking torque converter provides fast yet ultra-smooth gearshifts.
New Electronic Stability Programme (ESP) logic system improves dynamic response and handling with less intrusive intervention when a reduction in grip is detected.
New Tyre Pressure Monitoring System fitted as standard to all Arnage models.
Improved driver ergonomics thanks to 25mm increase in length of steering column and in vertical steering wheel adjustment.
Exterior design styling changes includes new dark finish to Arnage T front radiator and bumper grilles, standardised bright chrome finish to R and RL grilles, and Bentley 'B' badges on the D-pillars.
Underbonnet styling now features a black crackle finish to the Arnage T's inlet manifold, embossed Bentley logo on plenum chambers and new '63/4 LITRE TWIN TURBO' engine plaques.
Interior design updates include new hide-trimmed gearlever and chrome gearlever bezel providing access to semi-automatic transmission function.
New Thin Film Technology driver information panel displays more comprehensive and clearly accessible information.
Arnage RL model receives additional standard specification including rear centre armrest bottle cooler, veneered rear centre cushion box, rear rSAP master telephone system, and reversing camera (US, EU, Australia and New Zealand markets only).

Engine

Bentley's 6.75-litre V8 engine is the centrepiece of the 2007 Model Year Arnage development programme. This remarkable engine, the fundamental design of has served Bentley models proudly for nearly five decades, has been extensively re-engineered so the top speed of the Arnage T has risen from 168mph to 179mph, while the 450bhp Arnage R and RL's maximum speed increases by 13mph to 168mph.

When the first V8 engine was built in the 1950s, the design brief unwittingly benefited later generations of Bentley engineers. It was a very forward thinking design with an all-aluminium construction, a five main-bearing crankshaft, and a well-supported camshaft. The steps taken then laid the foundations for the longevity of the engine.

"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 powertrain and chassis director Brian Gush. "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."

That first 6.25-litre engine produced around 200 horsepower - 2007's 6.75-litre V8 has more than twice that output,. 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. Two new low-inertia turbochargers operate with far greater efficiency at lower engine speeds - they reach maximum turbine speed in half the time of the previous unit - thereby ensuring significantly reduced turbo lag and that prodigious wave of torque at any revs.

Furthermore, a re-profiled camshaft with an all-new roller tappet system provides revised valve timing and substantially improved refinement. These changes also deliver for increased power, enhanced durability and ensure compliance with European EU IV and US LEV II standards. Although the 2007MY 6.75-litre engine produces around 300 horsepower more than its 1959 predecessor, its fuel consumption is only 60 percent of the original and thanks to its advanced fuel injection and exhaust controls, its emissions output is an incredible 99 percent lower than Bentley's first V8.

Drivetrain and chassis

Such an impressive increase in power and torque is, however, of little benefit unless the powertrain is capable of delivering it to the driven wheels. For this reason Bentley's engineering team opted to introduce the latest six-speed ZF automatic transmission to the Arnage range. This system offers two further ratios than the previous gearbox and has several key advantages over its predecessor, according to Bentley:

The wider range of ratios is specifically tuned to each Arnage model, ensuring greater flexibility, response and refinement for every model.
Performance feel is also improved by using a sophisticated locking torque converter system which provides a more rapid response to throttle inputs.
Three transmission modes (Drive, Sport and Semi-Automatic) allow the driver to take full advantage of the new gearbox. Semi-Automatic mode is accessed by placing the gearlever into the sequential manual gear-selector gate, where a new ratio can be engaged simply by pushing the lever forwards or backwards.

Electronic management systems play a major role in providing fast, smooth gearshifts regardless of how the car is being driven, reckons Bentley. Previously the Arnage's engine and transmission were governed by independent electronic systems; in the 2007 Model Year, an uprated Bosch computer-controlled management system ensures that both parts work as a single unit to produce a supremely refined yet highly responsive drivetrain.

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

"As the engine speed approaches the point at which a gearshift is due, it signals to the transmission that it is time to shift, so the ratio changes are much quicker - it feels significantly faster from the driver's seat. Similarly, when the gearbox is ready to change up it asks the engine to reduce the torque just for the period of the shift, which adds to the refinement."

Another important development for the 2007 Model Year Arnage range is the separation of the sports suspension and sports gearbox settings, allowing the driver to select their preference for each system independently - via a 'Sport' button on the dashboard for the suspension and by positioning the gearlever for the transmission's Sport mode.

A comprehensive chassis tuning programme was instigated alongside the powertrain updates to ensure the Arnage's chassis can handle the additional performance. Refinements to the ESP logic system allow more spirited handling without any reduction in stability or safety.

The traction control system is extensively recalibrated with the aim of "avoiding unnecessary reduction in engine torque", said Bentley. The ESP system now monitors the car's overall stability rather than simply loss of grip to the wheels. This reduces the amount of intervention required and restores power earlier and more progressively, allowing the power of the engine to be fully exploited.

"We don't believe in creating power and then taking it away," says Brian Gush, Director, Powertrain and Chassis. "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."

Design

Following the detailed design updates made to the 2005 Model Year Arnage, the latest models receive further exterior styling changes.

'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," said 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 Arnage T gets a new dark finish to its front radiator and bumper grilles. A standardised bright chrome finish is applied to the R and RL grilles while Bentley 'B' badges have been applied to the D-pillars on all models.
A newly styled engine bay include a black crackle finish for the Arnage T's inlet manifold, while every model displays an embossed Bentley logo on the turbocharger plenum chambers and new '63/4 LITRE TWIN TURBO' engine plaques.
Additional optional extras include a 19-inch six-spoke disc wheel for the R and RL models, and 19-inch five-spoke 'Blade' sports wheel for the Arnage T.
Also available across the range is the famous winged 'B' mascot, which saw a welcome return this year on the Diamond Series Arnage. The iconic mascot - which can retract neatly into the grille surround - was originally designed by motoring artist F. Gordon Crosby and first used on the 1930 Bentley 8 Litre.
Interior design updates include a new hide-trimmed gearlever, chrome gearlever bezel, and new LCDs for the driver information panel. The Arnage RL model receives additional standard specification including a rear centre armrest bottle cooler, veneered rear centre cushion box, rear Bluetooth master telephone system and reversing camera.

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