Detroit, 7 January, 2002… Making its world debut at the NAIAS, the 450bhp, 168mph Arnage T is not only Bentley’s most powerful car in its history, but also the fastest production saloon in the world.

As part of the Bentley Series Two Arnage family, the Bentley Arnage T is the result of a three year project to re-engineer the outstandingly successful Arnage saloon from bumper to bumper. In this process not a single significant area of its design has been left untouched.

So extensive are the engineering modifications enjoyed by the Series Two Arnage that beneath its updated, but still familiar lines lies what is in many respects a new car. Every area of the car has been thoroughly evaluated for its suitability to the 21st century Bentley driver, and many have been comprehensively modified, some out of all recognition.

The Arnage T is the pinnacle model in the Series Two range. It will be joined later in 2002 by two other models, successors to the Arnage Red Label and Arnage Long Wheelbase.

HIGHLIGHTS

Introduction of the Arnage T, the fastest standard production four door saloon in the world and the most powerful road-going Bentley yet built. It produces 450bhp (336kW) and 645lb ft (875Nm) of torque, giving it more torque than any other car engine in series production. Top speed 168mph (270km/h), 0-60mph in 5.5 sec
(0-100km/h in 5.8 sec). Readily identifiable by numerous design features and famed black label badge, reserved for Bentley’s most sporting cars.
Total redesign of 6.75-litre V8 engine with minimal component carry over, twin turbochargers and Bosch engine management. Over 50% is all new and of the remainder, over 80% has been re-engineered.
New engine fully compliant with global emissions legislation to 2004.
Re-engineering of body in white to give dramatic improvements in torsional rigidity and therefore ride and handling.
New computer controlled sports suspension strategy to provide transformed handling while further enhancing ride quality.
First Bentley to be designed almost entirely in the virtual world using the latest Computer Aided Design and CATIA technologies. Advanced used of Computational Fluid Dynamics (CFD), Dynamic Crash Analysis (DCA) and Digital Mock Ups (DMU).
Introduction of ESP (Electronic Stability Programme).
Improved NVH (noise, vibration, harshness) isolation for better refinement.
Extensive styling changes inside and out including new bumper and sills, new sports seats and numerous interior detail changes.
New front and rear seat mounted thorax airbags, side air curtains; rear seats now equipped for ISOfix installation.
The first Bentley to be backed by the full resources of the VW Group, the largest car company in Europe.
Addition of rear anti-roll bar.
ENGINE

New 6.75-litre, V8-engine

The genesis of the new V8 engine can be found in Bentley’s decision in 1998 to offer the Arnage with the long-serving 6.75-litre engine as an alternative to the BMW-derived 4.4-litre powerplant offered at launch. The response from the Bentley-buying public was so overwhelming that very soon the larger engine powered every new Arnage. There could be no clearer indication of the strength of demand that remained for the fabled turbocharged aluminium V8 that first appeared in the Bentley Mulsanne in 1982.

Clearly, however, the engine was no longer in its first flush of youth and with ever increasing demands being put upon it by emissions legislators and a clientele that expects the best, it was evident that it would either need re-engineering or replacing.

Bentley’s engineers have sought to retain the fundamental structure of the engine, while modifying its internals and ancillaries to create a new powerplant that suits all the requirements of the 21st century Bentley driver.

For the Arnage T, the engine produces 450bhp (336kW) at 4100rpm and 645lb ft of torque (875Nm) at 3250rpm.

Adoption of twin turbochargers

The most obvious change is the adoption of two Garrett T3 turbochargers to replace the single T4 used until now. The advantages of a twin turbo layout are many and diverse but chief among them are the production of power and reduction of emissions. By using two smaller turbochargers with therefore considerably reduced inertia, the Arnage T engine produces not only 450bhp but also substantially reduced response times across a wider rev range.

This in turn means a more immediate throttle response and more of the torque beloved by Bentley drivers delivered even more quickly than before.

By using two turbochargers, Bentley has also been able to use close-coupled catalytic converters located close to the exhaust manifold, which is simply not possible for a Vee-formation engine using a single turbocharger. This means the catalytic converters heat up to their normal operating temperatures much more quickly, dramatically cutting emissions.

Internal engine modifications

Providing an engine that would produce more power, better response, lower emissions and even smoother manners required a lot more attention than simply changing the turbochargers.

Central to the philosophy of the new engine was the conviction that the out-going unit’s greatest strength – the tidal wave of torque at very low engine speeds – should not only remain intact, it should be enhanced. To achieve this and its emissions targets required a total re-evaluation of its internal operation at the most fundamental level. It was also decided to raise the maximum permissible engine speed from 4500 to 5000rpm; this was not to accommodate a higher power peak, which remains at 4100rpm, but to allow better use of the gearbox and the new gearing that has been chosen for the Series Two Arnage.

The actual block has been changed to move the water jackets much closer to the block and cylinder head interface, helping thermal management and reducing the risk of detonation inherent in a turbocharged engine such as this which is calibrated to run on standard 95RON unleaded petrol. The use of standard pump fuel has also been made possible by the greatly enhanced knock control capability of the Bosch Motronic ME 7 engine management.

Inside the engine there are new pistons that feature a revised crown configuration and have had their recesses removed to produce cleaner, more efficient combustion for greater power and reduced emissions.

The valve-gear has been totally renewed with a new camshaft featuring revised lift and duration. It operates on substantially strengthened pushrods with a revised rocker ratio and new rocker pedestal fixings to cope with the higher engine speeds. Valve lift is increased and new Nimonic exhaust valves fitted; these are the same size as before but are much lighter and have reduced stem diameters to cope better with the higher potential engine speeds.

The cylinder heads themselves have also been modified: they have been redesigned to accommodate the new valve train while particular attention has been paid to the port
areas to allow greater gas flow into the cylinders. The heads are also even more robust and are now bolted to the block rather than relying on the previous stud retention system. A new and stronger gasket is employed to cope with the higher cylinder pressures.

External engine modifications

Turbochargers aside, the single most important external change is the adoption of Bosch Motronic ME 7 engine management. This is the very latest and most sophisticated engine management system available and enables the Series Two Arnage not only to reduce its emissions and improve its response – it also facilitates the replacement of the Arnage’s traction control with Bosch’s Electronic Stability Programme (ESP). This helps stabilise the car when it detects a possible or partial loss of control, thereby radically enhancing its active safety.

The adoption of the Bosch engine management system also allows transformation of the way in which the engine is controlled. It offers better regulation of boost levels, exhaust temperatures and detonation control, all critical considerations in the pursuit of power and reduced emissions.

Finally it also means that the Series Two Arnage now has an electronic ‘fly by wire’ throttle without which the ESP stability system would not be able to work.

Another very important component in the new engine is a twin-skinned exhaust manifold that is now fabricated instead of being cast.

It gives considerably better gas dynamics and therefore enhanced performance and emissions. It has low thermal inertia and therefore heats extremely quickly, heating the catalytic converters and reducing emissions. Also each of the manifold lengths of the exhaust outlets has been individually tuned to produce optimal pressure waves and therefore maximum performance. The inlet manifold has also been tuned for maximum efficiency and sound quality.

There is also a single belt drive on the front of the engine, replacing the multiple belt system used until now. Not only is the new belt maintenance free it also reduces noise emissions and improves reliability.

TRANSMISSION

The GM 4L80-E four-speed automatic gearbox used in the Arnage Red Label has been retained for the Series Two Arnage. However extensive work has been carried out to optimise the transmission to the new engine specification resulting in enhanced smoothness and shift times of less than 0.4 sec.

While its internal ratios remain unchanged, the back axle ratio has been lowered to cope not only with the higher top speeds on offer but also to exploit further the immense engine torque, while offering even more relaxed running at speed. By raising the final drive ratio from 2.69:1 to 2.92:1, the Series Two Arnage now adds 36.78mph for every 1000rpm in top gear. Put another way, this means that at the UK legal motorway speed limit, the engine is turning at just 1900rpm.

In addition, the Series Two Arnage benefits from a new back axle that is not only lighter than that it replaces, but also has double the torque handling capability.

POWERTRAIN TESTING

The new powertrain has undergone a level of testing and evaluation unprecedented in the history of the marque, being tested around the world and in simulations at ambient temperatures from -40 to +50 deg C and at altitudes from -100 to +4000 metres.

One particularly punishing new test is to run an engine at maximum effort on the bench for 500 hours, punctuated only by thermal shock cycling. This means that once the engine is at its absolute maximum temperature, it is flushed through with ice-cold coolant to induce a maximum gradient of heat loss before heating back to maximum temperature again. This naturally expands and contracts all the castings in the engine, taxing joint faces, gaskets, bolts and numerous other fittings to an extent that would be almost impossible to replicate in the real world.

BODY STRUCTURE

All engineers know that, other things being equal, the stiffer the structure of a car can be made, the better its handling and secondary ride is likely to be. However if such stiffness is accompanied by a commensurate increase in weight, the advantage can be entirely negated.

The strategy for the Series Two Arnage was therefore to add further rigidity to an already stiff body in white without significantly increasing its weight. This would provide the most stable platform possible, allowing the improvements in the totally revised suspension to be shown to their best effect.

During the process, mounting points for ISOfix rear child seats have also been incorporated. ISOfix (standing for International Standards Organisation – fix) child seats are important as it is estimated that 60 per cent of all child seats are incorrectly fitted. By plugging an ISOfix compatible seat straight into the structure of the car, this possibility is removed.

To improve the Arnage’s overall rigidity, Bentley’s engineers took a blank sheet approach to the task, using advanced finite element analysis and computer modelling to define first
what was theoretically possible. This was then adapted to see what was practically possible once all other considerations – crash performance, packaging, fitment and trim in particular – were taken into account.

This was done to ensure the maximum advance in dynamic stiffness with a minimal knock-on effect in other crucial areas.

Once this work was done it was decided to add a brace inside the wheel arches, strengthen the sills, include an extra bow in the roof and reinforce the front bulkhead. Adhesive bonding materials have also been used around the door frames while new, stronger mounts for the steering column have been fitted. The result is a dramatic improvement in body in white dynamic stiffness from a first body mode of 41hz to 45hz for a weight increase of just 15.6kg.

The importance of this is that a car’s body is subjected to many excitation forces at many different frequencies, being fed into the structure from the engine, tyres and suspension. And the more distance you can make between those frequencies and the part at which the body will eventually start to vibrate in sympathy, the more comfortable and smooth the ride will appear to its occupants.

CHASSIS

Bentley’s aim in the transformation of the Series Two Arnage chassis was twofold. First there was to be a general enhancement of both ride and handling across the model range, but there also had to be an entirely separate strategy for the new Arnage T, the most sporting Bentley saloon in history. The intention was that the Arnage T should handle like no other Bentley before it, yet that it should retain the primary ride comfort that is synonymous with the marque.

Work began in early 1999 on improving the Arnage’s suspension by using Adams modelling and bespoke Bentley programmes to put the car through simulated manoeuvres on the computer and assessing the implications on ride, roll, pitch and yaw characteristics when different spring, damper and bush rates were used.

The results were then built into prototype cars and proved not only on VW’s test facilities, but also in places as diverse as the famed Nurburgring race track, the Pyrenees, Finland, the Alps and, of course, normal public roads in the UK and across Europe.

Suspension changes

The first decision was to retain the basic architecture of the suspension, which already featured an optimal double wishbone layout at each corner. Thereafter every other aspect of the suspension from springs and dampers to its very geometry was examined exhaustively to create and refine the finest chassis to be used by a Bentley. During this process the Electronic Stability Programme (ESP) was also included. It was also decided to move the handling balance of the Arnage towards greater neutrality. Hence understeer – the tendency for the nose of the car to run wide in a corner - has been ‘dialled out’ of the chassis to offer the driver a greater degree of control, while overall stability is enhanced.

The most fundamental suspension change is the introduction of a rear anti-roll bar and the stiffening of the front anti-roll bar to bring an extra degree of roll control while allowing greater scope with spring and damper settings to tailor the suspension to the differing needs of the model range.

An idea of how sporting the Arnage T chassis is can be gained from the fact that it has 57 per cent greater roll stiffness than the Arnage Red Label.

In addition the front springs are stiffer though the presence of the rear anti-roll bar has allowed Bentley’s engineers to retain the original rear spring rates and still improve roll control.

The variable rate dampers have been tuned to give a stiffer, more sporting ride for the Arnage T. This has been done by modifying the dampers’ internal valving and reprogramming the control algorithm, with its 100 different control parameters.

This enables the car to switch between three different operating modes from sport to comfort depending on the speed and style of driving. The actual geometry of the suspension was fully analysed front and rear.

Ultimately though, the only change deemed desirable was to the rear camber, to provide more negative camber, and thereby achieving a flatter tyre contact patch during cornering.

Wheels and tyres

The wheels for the Arnage T are of 18in diameter, carrying 255/50 ZR 18 section asymmetric Pirelli P-Zero tyres. The Arnage T uses a five spoke design and an all new 19in three piece split rim wheel with 255/45 ZR 19 tyres is offered as an optional extra.

Work has continued with Pirelli to tune its tyres specifically to the Series Two Arnage. Construction changes have led to a reduction in noise levels, while much work was done to tune the tyre pressures precisely to the spring rates.

Electronic Stability Programme (ESP)

The adoption of the very latest Bosch ESP 5.7 stability system has dramatically enhanced the Series Two Arnage’s active safety capability. Individual sensors monitor all relevant issues such as wheel speed, steering angle, yaw, pitch and throttle opening and continually feed the information back to a central ECU. This is programmed to follow an algorithm that sets certain parameters within which the car is judged to be safe and under control.

The moment one of these parameters is breached, the ESP will use whatever combination of throttle and individual brake control is required to re-establish stability.

This contrasts starkly to a standard traction control system that merely cuts the power when a loss of traction is detected.

And clearly while not even ESP can change the laws of physics, it does provide another effective line of defence for drivers unlucky enough to be caught out by changing road conditions, the actions of other road users or simple bad luck.

That said, Bentley’s engineers are acutely aware that their customers enjoy spirited driving more than most and the parameters that have been chosen for the ESP are specifically tailored towards unforeseen emergencies and do not, unlike some other stability systems, spoil the driver’s fun. It can be switched off altogether though most drivers will find it so unobtrusive in its operation that most of the time they will be unaware the system is even active.

Other chassis modifications

New hydraulic mounts were made for both the engine and gearbox. These have been designed not only to reduce vibration transmitted into the cabin, but also give better dynamic control of the powertrain itself. Excess movement in the engine and transmission can have quite a dramatic effect on a car’s ability to turn into a corner and its ride quality. As a result of a prolonged development programme, these effects have been minimised. The Series Two Arnage retains near perfect weight distribution.

In addition to this, a lot of work was carried out on the steering with modifications made to both the system stiffness and hydraulic valving to increase linearity for a more progressive turn-in and to create a more consistent off-centre response.

The steering rack has a constant ratio and is also speed sensitive, with steering weight that tunes itself to the speed of the car to refine further the quantity and progression of feel at differing speeds.

The result of this work is better steering feel, greater steering precision and a much improved sense of stability, particularly at the speeds at which the Arnage T is capable of operating.

Brakes

The brakes of the Arnage were completely uprated in 1999 with the introduction of 18in wheel rims and, for that reason, no further modifications were needed to the massive ventilated discs at each corner. Nevertheless, while the brake specification has remained unchanged, aerodynamic modifications to the flow of air to the brakes has led to improved brake cooling, especially at high speeds.

AERODYNAMICS

An all new aerodynamics department was established at Crewe in 1999 and one of its first jobs was to go through the Arnage from end to end to enhance its aerodynamic performance.

The aim with the Series Two Arnage was to improve both its drag and lift characteristics without spoiling its appearance and, to this end, a number of measures have been taken.

Most notable is the integrated boot spoiler on the Arnage T that provides better stability at speeds approaching 168mph and also ensures that aerodynamic performance is matched to the weight distribution of the car at all speeds.

The main work was done using full sized cars in the wind tunnel at MIRA (Motor Industry Research Association) while detailed work to determine seal specification and glass thickness has been completed at a wind tunnel owned by Audi, the most advanced of its type in Europe.

Nor was aerodynamic work restricted simply to improving lift and drag: extensive work was also completed to ensure that enough air was being fed to the engine, radiators, intercoolers and brakes to cope with the most extreme use imaginable.

ACOUSTICS

For the Series Two Arnage, the acoustic performance of the car was assessed at whole car, systems and component levels to improve not just overall refinement in terms of road, wind and tyre noise, but also powertrain sound quality, secondary ride comfort and driveline refinement too.

With the right sound for a Bentley being as much a matter of subjective opinion as objective fact, extensive research was conducted among existing and potential customers to discover exactly what quality of sound was most wanted from the marque. Then these aims were subjected to advanced sound quality synthesis to make sure that the components in the car responsible for sound generation matched the aspirations of the customer base as accurately as possible.

Once the theory had been completed it was time to test the findings on Bentley’s own Hydropulse four poster rig in Crewe, which is capable of replicating road conditions but without the inconsistencies caused by weather and traffic. Naturally extensive testing and final sign-off were conducted on the road.

These tests led to modification of the powertrain, exhausts and chassis as well and numerous detailed but critical alterations to panel gaps, aperture sealing and interior trim.

SAFETY

The major enhancement in passive safety for the Series Two Arnage is the incorporation of side thorax bags for both front and rear seat passengers, and the installation of full length side air curtains. Thanks to the excellent structural nature of the Arnage (it is capable of passing Federal side impact tests without airbags) it was possible to apply the new airbag systems to the existing structure rather than starting from scratch and developing an all new structure. Even so, over 20 Series Two Arnage crash tests were conducted to ensure the best possible performance of the system.

The sidebags have been packaged into the outboard sides of the front and rear seats rather than in the doors meaning that wherever the seat is positioned, the airbags will always be located where they can offer maximum safety to the cars’ occupants.

The decision to fire the airbags is taken within 10 milliseconds (0.01 sec) of impact and 20 milliseconds (0.02 sec) later, the airbag system will be fully deployed. The side curtains are deployed simultaneously from the cantrail and A-pillar.

Safety was also a primary consideration in the strengthening of the body. Much more advanced computer modelling allowed an unprecedented degree of accuracy and detail during simulated crash tests.

This detailed crash analysis led not only to changes in construction - there is a new brace between the A-pillar and front damper tower to improve frontal impact performance - it also led to improvements in the method of construction.

The new side airbags and curtains join an already strong arsenal of passive safety features including two front airbags, front seat belt pre-tensioners and four channel ABS.

STYLING

Exterior

Bentley design chief Dirk van Braeckel knew that customers for the Bentley Arnage T would want to drive a car that was clearly an Arnage, but at the same time, one that could be seen to be considerably, if subtly enhanced. Therefore numerous design changes were effected, none world changing in isolation but as a whole, designed to provide the
Arnage T with a new and even more purposeful identity.

One of the least visible but most significant of these changes is the use of the famed Black Label badge, reserved only for the most sporting Bentleys and otherwise used only by the Continental T.

At the front there is a new bumper with a lower air dam, which not only reduces lift but also provides a more solid appearance. There are larger openings in the bumper to provide extra air to the charge coolers and brakes, while front fog lamps have been incorporated. The intakes in the bumper are now covered by the same laser-cut matrix that is used for the radiator grille.

Moving to the side of the car, new thicker sills have been designed, while all the chrome on the sides, front and rear of the car has been removed, though the chrome used for the glass and door frame areas has been retained. If specified, the new three piece, split rim, five spoke 19in alloy wheels add an additional degree of purpose to the car’s profile.

Like the front bumper, the rear bumper has been restyled to provide a more purposeful stance and to arc around the large diameter twin tail-pipes. Parking Distance Control (PDC) sensors are incorporated into both front and rear bumpers.

Also at the rear there is an integrated rear spoiler within the lines of the bootlid to provide further evidence of the Arnage T’s performance potential, as well as a useful reduction in lift at speed.

Further detailed styling work abounds around the Arnage T. The door handles have knurling on their back faces, pursuing a theme first shown on the Bentley Continental
T 440 and even the key has been totally redesigned to feature a blade that folds into the fob, which also now contains the remote controls for locking and unlocking the car.

Interior

The interior of the Arnage T has received even greater attention than its exterior. Perhaps most notable in a wide range of enhancements are the seats. Bentley is one of just a few manufacturers left in the world to design and manufacture their seats entirely in-house, and has spent two years building CAD-profiles of the best seats on the market against which to benchmark its own products. The result is seats that offer both more comfort and support, while providing a much more sporting look. They also carry new heaters with improved heat distribution.

Their distinctive looks come from a combination of a diamond pattern using perforated Connolly hide and contrasting stitching; they also carry an embroidered Bentley motif.

Looking elsewhere inside you will find extensive use of engine-turned aluminium for both the instrument surround and the waist rails in the doors. The door covers themselves carry the same distinctive diamond pattern as the seats while extensive knurling is used for the sill buttons, door handles, organ stop ventilation controls and lighting switch. The instruments carry distinctive white on black lettering as an optional extra.

The Arnage T cabin also features a bespoke steering wheel and gear selector, a ‘Sport’ mode button for the transmission and a distinctive black ‘Engine Start’ button, while drilled pedals can be ordered as an option. There are new grab handles in both the front and rear, and the roof lining is made from perforated hide. The decision was also taken to darken the stain on the wood within the Arnage T to create a much more sporting atmosphere within the car.

Ergonomically the Series Two Arnage has benefitted from a redesign of the roof console, to create a cleaner, more user-friendly design. A DVD-based satellite navigation system is now available and is displayed on a pop-up screen on top of the dashboard.

DESIGN TECHNOLOGY

Some of the most important elements that have allowed the Series Two Arnage to make such a quantum leap forward are not actually fitted to the car. And unlike any Bentley in the marque’s 83 year history, the Series Two Arnage was designed entirely in the virtual world.

Using a CAD database and CATIA design technology, Bentley’s engineers were not simply able to design and examine individual components – a relatively old technology – but were also able to see through Virtual Product Modelling (VPM) exactly how each component, down to the smallest washer, interacts with those around it.

This means it is possible to design a car on screen in the certain knowledge that when it is built there will be no overlaps, no component clashes and no misfits. All components are digitally stored in the database and are accessible in such a way that it is not possible for two or more different departments to work on the same component without the other’s knowledge. This is important because it is very rare that any single item is the sole concern of one department and it prevents different and conflicting design alterations happening to the same component.

Using this technology it is quite possible to follow the path of a drop of fuel as it enters the fuel filler and monitor its progress through the entire system until it emerges from the tailpipes as exhaust gas.

EQUIPMENT

Personal Commissioning

Any new Bentley will be one of the best equipped cars money can buy, but unlike other manufacturers, for Bentley this is just the beginning. Through its legendary Personal Commissioning department, Bentley can tailor an Arnage to the precise specification of the customer.

Customers can choose from an effectively unlimited resource of trim and specification possibilities that can turn a car into a mobile office or, by using a vast choice of hides, wood and upholstery possibilities, make a genuinely unique and luxurious travelling environment.

Standard Equipment

The extensive list of standard equipment includes: Connolly leather; Wilton carpets; automatic climate control; driver, passenger and four side airbags, full length side air curtains; four channel anti-lock brakes; Bosch ESP stability control; flip up central navigation display with DVD satellite navigation; cruise control; electrically adjustable front seats with four memory settings, electrically adjustable rear seats; seat heaters in all four seats; audio system with six-CD stacker; front and rear parking distance control sensors; volumetric and perimetric alarm with rolling code transponder immobilisation and tow away protection.