The aim from the start of the Bentley Continental GT project was to create a car with an unrivalled performance envelope, so that it would not only be quicker and more powerful than any rival on paper, but that these extraordinary talents would also be able to be used safely and to the full in the real world. The Bentley Continental GT is not and never was about theoretical performance potential - every aspect of its ability has been specifically tailored so that it is not just possible to access its performance, it is easy and natural.
Moreover, the Bentley Continental GT concept also dictated that the resulting car would recognise that, though we would all wish otherwise, road conditions in all markets mean that frequently its owners will not be able to make use of its full potential. Indeed in some regions traffic conditions are such that being able to extend such a car is more of a rare treat than an everyday occurrence. Which is why in addition to being able to thrill its occupants at a moment's notice, the Bentley Continental GT is also configured to comfort and cosset them the rest of the time - in the tradition of a true British Grand Tourer.
The Bentley Continental GT is the first product designed entirely under the patronage of the Volkswagen Group and a £500 million investment in the marque has enabled a transformation of the site at Crewe. This made it possible for the Bentley Continental GT to be designed, engineered and assembled on site.
The investment has also made it possible for Bentley to recruit over 400 new staff to Crewe, giving Bentley greater independence and control over its future than at any time since it first passed into proprietary ownership in 1931.
Engine
The heart of the Bentley Continental GT is its 5998cc, four camshaft, 48-valve, twin turbocharged W12 engine. It can now be revealed that its power output, hitherto quoted as 'in excess of 500bhp', is in fact 552bhp (560PS) (411kW) at 6100rpm. Maximum torque is 650Nm (479lb ft) which may sound an impressive enough statistic in isolation but its true significance only become apparent when you learn that it is generated at just 1600rpm. Typically, a performance car engine will force the driver to wait until it is spinning at between 3-5000rpm before it will deliver maximum thrust; in the Bentley Continental GT it's all there at barely more than idling speed. No other car in production makes its torque so instantly accessible.
It is no secret that the basic engine architecture has been supplied to Bentley from its parent company, the Volkswagen Group, but by the time Bentley's powertrain team had finished re-engineering it to an exclusive specification for the Bentley Continental GT, it could be truly considered a unique engine in its own right.
Clearly the major engineering challenge was to adapt the engine to accept forced induction, a process that required major re-engineering of the block, the replacement of many internal components and all new inlet and exhaust manifolds. The result would have to cope with a rise in output from 420bhp in standard form to 552bhp once installed under the bonnet of the Bentley Continental GT.
A huge amount of work was also undertaken to make sure the Bentley Continental GT could use very efficient air to air intercooler. Fitting them within the already cosy confines under the Bentley Continental GT's bonnet was not the matter of the moment, but Bentley's engineers regarded their inclusion in the specification as not negotiable and, after several months work, they were integrated into the under bonnet package.
The Bentley Continental GT also uses a dedicated exhaust system, using two six-into-one manifolds. Much attention has been paid not simply to ensure the exhaust provides maximum efficiency, but also that its sound is appropriate to the fastest Bentley road car in both tone and volume.
The turbochargers are made for Bentley by renowned specialists, KKK, and need operate at only the comparatively conservative boost pressure of 0.7bar to provide the Bentley Continental GT with its headline performance. Given this, the existence of maximum torque at 1600rpm and the engine's 6-litre capacity and it's easy to see how turbo-lag, the sole undesirable side-effect of this variety of forced induction, has been effectively removed from the equation. As with all Bentley-designed powerplants since the birth of the company in 1919, smooth power is not something you need to wait or ask for - it is there, at your disposal at every point of the rev-range from idle to its 6100rpm red-line.
Such is the power of the Bentley Continental GT's powertrain that Bentley engineers took the decision to reinforce its already substantial engine mounts with Kevlar bindings to make sure it does not move even under the most extreme circumstances.
Powertrain testing
The engine in the Bentley Continental GT has undergone some of the most gruelling and exhausting test procedures of any engine in order to ensure that it can be depended upon to accommodate all and more than any owner could ever need. Naturally prototypes have and continue to rack up millions of miles in some of the hottest, coldest, driest and most humid places on earth, but perhaps no single test illustrates the relentless pursuit of engineering perfection than those tests performed with the engine out of the car and sitting on a bench.
Perhaps the most eye-opening of these is a test where the engine is switched on and revved to maximum revolutions (6100rpm) from cold and then left there, not for a few minutes or even a few hours. It is left to run at maximum speed for 100 hours or, put another way, over four Le Mans in a row.
Another test puts the engine through an advanced programme of cyclical accelerations, decelerations and steady state running at all points in the rev range for 500 hours non-stop or, to put that perspective, just four hours short of three weeks.
The engine has also been exposed to prolonged thermal shock cycling where internal temperatures are swiftly brought to a peak whereupon its coolant is replaced by ice-cold fluid in order to induce the swiftest possible drop in temperature before the engine is re-heated up to maximum temperature again and the process is repeated.
Transmission
Not many gearboxes are capable of handling the extraordinary torque loadings that the Bentley Continental GT engine is able to produce and none so far fitted to a luxury coupé has had the benefit of six gears. Yet with the help of its partners at ZF, that is exactly what Bentley has provided for the Continental GT. Designated 6HP26, the new gearbox is the most advanced of its kind in the world, offering not only six ratios but also the ability to lock up its torque converter in every gear, providing effectively manual gearchanges via either the gear lever or steering wheel paddles.
The gearbox itself is exceptionally light and compact, given the torque it must handle, indeed it has almost 30 per cent fewer components than a conventional five speed automatic, decreasing weight and improving both reliability and efficiency. Though variants of this gearbox have been supplied by ZF to other luxury car manufacturers, that used by the Bentley Continental GT is distinguished by being adapted for use with a four-wheel drive transmission and has been further modified for use in the Bentley Continental GT.
Not only does the Bentley Continental GT carry bespoke gearing, tailored precisely to the unique torque characteristics of the engine and the car's exceptional top speed, it has also been fundamentally redesigned for installation in the Bentley, placing the front differential ahead of the torque converter in order to push the front wheels as far forward as possible, creating a minimal front overhang, an inimitable Bentley design trait. Direct drive equates to 22.7mph (36.5km/h) per 1000rpm which, with a 0.691:1 top gear ratio, gives 32.85mph (52.86km/h) per 1000rpm. At first this may appear a relatively long-legged ratio, after all the Bentley Continental GT will sit at the UK national speed limit (70mph) with just over 2100rpm on the rev-counter. In fact, and in keeping with the car's extreme sporting aspirations, this ratio has been chosen to ensure that maximum power and maximum speed coincide as closely as possible.
All-wheel drive
Pointing the power in four directions was part of the original strategy for ensuring the Bentley Continental GT would remain, safe, usable and enjoyable in all weather conditions routinely found around the world.
The system used employs a central Torsen (TORque SENsing) differential and a free differential on each of the front and rear axles. Both the front and centre differentials have individual cooling radiators.
After exhaustive investigation and a substantial test programme of available alternatives, Bentley's engineers decided to divide the drive equally between the front and rear axles, giving a conventional 50:50 torque split. This is the combination that was found to be best at providing not simply the safety demanded of a car with this performance potential, but also the most favourable handling response.
Naturally this front to rear ratio is infinitely variable according to available grip and the Torsen differential together with the 4 wheel ASR can sense slip of less than one per cent and act accordingly, apportioning the engine's torque to either the front or rear axle. It would, in reality, take exceptional conditions for this to happen such as both wheels of one axle being on black ice but in more conventional circumstances the Torsen differential will always be able to optimise the torque loadings between the axles.
Thanks to the Bentley Continental GT's advanced electronic stability programme, the need to equip each axle with a limited slip differential is obviated. When slip is detected at one wheel, the ESP system can apply the brake individually to that wheel and allow the torque to be transferred across the axle to the tyre with the most grip. In normal use this system acts entirely unobtrusively but it does, in fact, possess the ability to keep the Bentley Continental GT moving forward when traction is available to just one of its four wheels. It is true that luxury coupés rarely find themselves in these conditions but it is also true that this is because their hitherto practical limitations have tended to keep them from places where such circumstances are more likely to occur. But with all-wheel drive, advanced traction and stability systems (not to mention its spacious interior, large boot and ski-friendly through-loading facility), the Bentley Continental GT will easily take its occupants to remote mountain resorts where no other luxury coupé would dare to follow.
Electronic Safety Systems
ABS anti-lock brakes, HBA (Hydraulic Brake Assist) and EBD (Electronic Brakeforce Distribution) in conjunction with the Bentley Continental GT's varied array of other defences designed to keep the car under control.
These include ASR traction control that employs the ABS sensors to detect when traction is lost at either end due to a combination of a low grip surface and an excessive application of power. Under these circumstances, the ASR will instantaneously cut the power until traction is restored.
As mentioned earlier, the Bentley Continental GT also features the latest Electronic Stability Programme (Bosch 5.7). This ESP system, which necessitates the use of a fly-by-wire throttle, operates by a system of sensors analysing a number of different parameters such as speed, throttle opening, steering angle and the car's yaw and pitch. When one of these parameters is breached, indicating a possible or impending loss of control, the ECU is informed and appropriate action is taken. Depending on the nature and severity of the situation this might amount to little more than throttle modulation or it could involve the targeted application and release of individual brake callipers until full control is restored.
The final weapon in this armoury is MSR drag torque control. This is an intermediate, electronic control system, designed to intervene before a potential loss of control is addressed by ESP or ABS. During deceleration it modulates engine braking to ensure deceleration is consistent, swift and helps remove the possibility of a wheel locking when the transmission changes down on a reduced grip surface.
Body Structure
It is also true that the potentially positive effect of adding stiffness to a car's bodyshell is entirely negated if the weight of that shell rises in proportion to the additional stiffness gained.
When presented with a brief for the Continental GT, Bentley's engineers were told that nothing less than exception torsional rigidity would enable the Continental to meet its dynamic targets. And the challenge they faced was providing such stiffness to a car with such a long wheelbase relative to its overall length and one which, thanks to its pillarless design, lacks a B-post between the front and rear side windows.
The first step to realising its targets was taken in the virtual world. Every single component on the Bentley Continental GT was designed on a computer and integrated into three dimensional digital models of the car. Using the latest Computer Aided Design (CAD) technology alongside Digital Mock Ups (DMU), Finite Element and Dynamic Crash Analysis (FE and DCA), Bentley's engineers were able to predict, analyse and enhance the Bentley Continental GT's structural integrity long before the first prototype was built.
Next, Bentley's engineers turned to adhesive technology. Adhesives have played a vital role in aircraft and aerospace technologies for some time (where they are used, for instance, to attach wings to aircraft fuselages) but it is only now that their full potential is being realised in the arena of car design. If understood correctly and used properly, adhesives can bring huge improvements to a body structure's rigidity with a minimal increase in weight. Adhesives are therefore used throughout the structure of the Bentley Continental GT, but particularly where there are long seals, such as around the door apertures.
Another emergent technology employed for the first time by Bentley is laser-welding. This process is expensive but, by introducing a new level of control into the welding process, it allows a considerable extra degree of strength to be introduced into each weld while, at the same time, ensuring minimal wastage and therefore saving weight.
Chassis
The Bentley Continental GT is without doubt the most sporting Bentley since the original company went into liquidation in 1931, but it would be no kind of Bentley at all if it was tuned to provide invigorating handling at the expense of a bone-jarring ride. The Bentley Continental GT is as its name describes, a long distance British Grand Tourer and while capable of being enthralling to drive, it also recognises that most of the time it will be driven on motorways or in towns when handling response will always be of secondary interest to overall ride quality.
Therefore, in the spirit of no compromise it was laid down that the Bentley Continental GT had to be as comfortable as it was quick, as responsive as it was restful. This was no mean feat to achieve and Bentley's engineers had to turn to one of the most sophisticated suspension arrangements ever configured to realise it.
Suspension at the front of the car is provided by twin upper and lower arms that converge as in a conventional wishbone arrangement but, in fact, never meet. The system is described as a 'virtual king pin axis' arrangement because the pivot point, where the arms would eventually meet is actually in the plane of the wheel rather than at a point in-board of the wheel.
The problem with the conventional system is that the torque loadings will only not be felt by the driver if they are equal either side and therefore cancel each other out. But if one wheel slips on a low friction surface, the loadings become unequal and this is fed straight back to the driver through the steering wheel. But by having the axis in the plane of the wheel, the torque is not created in the first place. The result is a car capable of putting phenomenal amounts of power through its front wheels without risking the dreaded 'torque steer' that would otherwise afflict it.
The rear suspension of the Bentley Continental GT is a multi-link arrangement designed to promote stability under all conditions be they braking, acceleration or cornering. Using trapezoidal wishbones and tie rods to give the rear tyres a firm foothold on the tarmac regardless of loading, this system plays a critical role in assuring that the Bentley Continental GT meets its targets for both ride and handling.
Much of the suspension at the front and rear, including all control arms, are made from aluminium that not only helps reduce the weight of the car but, critically, also keeps unsprung mass to a minimum, helping to achieve optimum ride quality.
Self-levelling air suspension has also been specified as standard equipment for the Bentley Continental GT. Much more expensive than a conventional steel spring, air suspension brings many benefits that would otherwise have been denied to the Continental GT. Air suspension works very simply with air-filled rubber bellows acting within a sealed tube with a concentric damper in the middle. As the wheel moves up, it compresses the air in the bellows which then offers resistance and thereby a springing effect.
One of the main advantages of air suspension over a steel spring is that the laws of gas dynamics mean that if you increase the mass on the axle, it compresses the spring further so the natural frequency of the car bouncing on its spring is held nearly constant whereas in a conventional system the frequency would become lower. This can be exploited to ensure that the car never suffers from that stodgy feeling that affects all steel sprung cars when they are heavily laden. In addition, the pressure acting on the spring is uniform across the entire strut whereas any conventional spring will inevitably be subject to some side loadings.
Another crucial benefit of air springs is the scope it provides in being able to tailor the car's ride characteristics. By carefully shaping the bellows, you can ensure that as they go up and down, they also go in and out effectively varying the spring rate as they do. The further in they go, the less air they contain and the softer the springing will consequently be. The bellows on the Bentley Continental GT are therefore designed to be quite narrow at the centre of each wheel's movement so that the suspension is relatively soft about its central point with obvious benefits in ride quality. Then, as the springs are compressed or expanded through acceleration, braking or cornering, the bellows widen to accept more air, firming up the ride and providing an extra level of control precisely when it's needed.
The final primary advantage of air suspension is packaging. If you were to ask a conventional spring to provide the same low frequencies that the Bentley Continental GT can achieve, there are only two ways of achieving it. You can either make the spring very long at which stage it can become unstable under compression, or you can shorten and widen it, bringing inevitable packaging problems. Using an air spring has allowed Bentley's engineers to allow for a much wider range of frequencies within a given space.
Air springs also allow Bentley to lower the ride height of the Bentley Continental GT at speed, optimising its aerodynamic performance. Currently the suspension is programmed to lower the car by 15mm at 100mph (161km/h).
The dampers used on the Bentley Continental GT are continuously and infinitely variable and the most sophisticated yet seen on a Bentley. Controlled entirely by computer, the dampers possess the ability to change their characteristics many times during a single 'event' such as a wheel moving up and down over a bump.
The electronics are so sophisticated they don't merely look at a force and react accordingly - they monitor the entire car. One example of how this works to the benefit of the Continental GT's ride comfort is that the computer can decide to let a wheel move to accommodate a single event if the car itself is in a fundamentally stable state. So if a bump is encountered, the damper will allow the wheel to travel upwards in the normal way. If however the body, let us say, is already moving downwards in reaction to an immediately prior event, the computer will analyse the relative movement of body and wheel and, if need be instruct the dampers to stiffen, thereby checking the upward motion of the wheel towards the descending body.
The overall set-up of the suspension has been configured to make the Bentley Continental GT an inherent mildly understeering car in steady-state cornering. This approach has been adopted primarily because Bentley believes that oversteer is a condition that should only ever arise at the driver's command. A car with low levels of natural understeer will, when the limit of adhesion is finally broached, gently start to run wide in a corner, a condition that can easily be cancelled by a simple lift of the accelerator. Bentley believes this is undoubtedly the safest and therefore the only responsible route to take.
That said, Bentley is equally aware that most Bentley Continental GT drivers will be of the 'press on' variety and have made it possible for the engine's torque to be used to overcome understeer in certain conditions, allowing the car to adopt a stance of neutrality or even mild and controllable oversteer, regulated by the ESP system.
Steering
The Bentley Continental GT features rack and pinion steering with speed sensitive Servotronic power assistance. The rack and pinion was chosen as it is the most precise form of steering available and offers great feel to the driver, an essential consideration in a car such as this. The rack has been designed with a fixed ratio so as to provide maximum linearity and consistency across the locks and has been equipped to give excellent feel both on and off-centre.
Wheels and tyres
The Bentley Continental GT uses the same size wheels and tyres on both the front and rear axles after extensive investigation revealed this to be the optimum solution for a front engined car such as this when fitted with four-wheel drive. Two wheels will be available with 19in rims as standard and 19in split rims as an option. Tyre size is 275/40R19. These sizes have been chosen not only because they fit the ride and handling requirements of the Continental GT, but also because either can be fitted without changing the overall gearing of the car.
Brakes
The Bentley Continental GT is equipped with the largest brakes ever to be fitted to a standard production car. The ventilated front discs have a 405mm diameter (15.9in) and are 36mm (1.4in) thick, making them wider than the actual wheels of most production cars. Ventilated discs are also used at the back, this time of 335mm width (13.2in) and 22mm thickness (0.9in).
These brakes are not available on any other car, indeed they were created specially for the Continental GT by Teves to a specification laid down by Bentley. Teves were also responsible for their appropriately huge callipers.
The reason Bentley chose a brake specification beyond that yet offered on any production road car is simply that it holds the conviction that the Bentley Continental GT should stop as well as it goes.
The energy contained within a fully laden Bentley Continental GT travelling at around 200mph is naturally considerable. Through months of real world tests and computer analysis it was determined that nothing less than the finest braking system in the world would be capable of delivering not only the retardation Bentley required, but also the ability to do so again and again with no fade or loss of performance.
This formidable braking hardwear is also backed by a comprehensive software package. In addition to Hydraulic Braking Assistance (HBA) and anti-lock (ABS) and drag torque control (MSR), the Continental GT also comes with Electronic Brakeforce Distribution (EBD). This system monitors the level of grip available to each tyre and apportions braking force accordingly. This not only helps reduce stopping distances but also greatly enhances the feeling of control enjoyed by the driver under heavy braking.
Aerodynamics
The role played by aerodynamics in modern car design has advanced considerably from the age where making the smallest hole in the air is the most important consideration. Aerodynamics affect almost all areas of the car and without both the exploitation as well as the avoidance of the airflow, no modern car will realise its full potential.
And the faster the car, the more important are its aerodynamics, not simply to realise such speeds, but also to keep the car stable and its under-bonnet temperatures cool.
The Bentley Continental GT's shape can be said to be a thoroughly modern interpretation of classic fastback design and as a result it boasts the enviably low drag coefficient of just 0.32. However one of the historical drawbacks of such a shape is that if the airflow is allowed to spill off the back of the car unchecked, it creates classic conditions for encouraging rear-end lift. This could potentially change the balance of the car, alter the effective weight distribution and create unwanted instability.
To counter this, the Continental GT has two specific aerodynamic devices, neither of which is immediately visible to naked eye when the car is stationary, that takes the potentially threatening airflow and turns it to the car's advantage.
The first is a rear spoiler that lies across the base of the rear windscreen and deploys once the car is travelling at above a certain speed. This effectively interrupts the flow of air coming off the back of the car and uses it actually to push the car harder onto the road rather than let it create unwanted lift. Working in close conjunction with the rear spoiler is a diffuser underneath the back of the car, which not only contributes greatly to the car's overall stability, but also helps extract air from underneath the car and this reduces drag.
Another crucial responsibility of the aerodynamics team is to ensure there is sufficient airflow to and from all heat-generating components. One look at the displacement of the engine, its power output and the tightly packaged under-bonnet area gives some idea of the challenge involved. But in fact, the cooling requirement is that the Bentley Continental GT should be able to run fully laden in 40°C ambient temperature and at maximum speed until it has drained its fuel tank - a tougher test by far than will ever be replicated by any owner on the public road. To achieve this, thousands of hours were spent creating and studying computational fluid dynamics data (CFD) to ensure the correct airflow to all areas under the bonnet and to the brakes. In those areas where this flow in inherently compromised, (such as for both the front and central differentials) individual cooling radiators have been installed.
Acoustics
In many luxury cars, the primary acoustic aim is to reduce noise intrusion from the wind, road, suspension and powertrain to create the greatest level of refinement possible. But when you are charged with creating an all-new Bentley some rather more subjective and no less important considerations need to be accommodated. In short, the Bentley Continental GT needs not only to look like a Bentley from bumper to bumper, it needs to sound like one too.
Bentley's acoustic engineers have been at work since the very start of the Bentley Continental GT project deciding first how the car should sound and then determining how that sound should be achieved. So important is their work that they were able to influence the design of both the intake and exhaust manifolds to make sure a true, unique and instantly identifiable Bentley soundtrack would greet the occupants. Bentley also carried out extensive customer research among existing Bentley owners and prospects who will be new to the marque, in conjunction with benchmarking the sound quality and quantity of other luxury sportscars.
The sound of the Bentley Continental GT is therefore deep, smooth, muscular and inspiring
In keeping with its Grand Touring aspirations, the Continental GT has also been configured to be an extremely refined car. In pursuit of this, the design has been helped by the provision of an astoundingly smooth engine and a very rigid bodyshell. These have provided Bentley's engineers with a platform that already possesses minimal noise, vibration and harshness (NVH) characteristics.
Beyond that, the task was to investigate every component, every system and the car as a whole to make sure no unnecessary NVH sources were inadvertently designed into the car. This work was carried out first in the virtual world and was then incorporated into the wind tunnel programme.
It continued on Bentley's own Hydropulse four poster rig at Crewe which replicates road conditions without the potential for inconsistency caused by changes in weather and traffic and, of course, on real roads around the world to ensure that every part, from the smallest seal to the body structure itself, contributed to making the Bentley Continental GT the most refined car in the marque's history.
Use of Electronics
There are many elements of the Bentley Continental GT's specification that deserve to be described as extraordinary but perhaps none more so than its use of electronics.
Consider these points: Each Bentley Continental GT contains approximately two miles (3.2km) of cabling and the main wiring harness alone weighs over 50kg. A Continental GT also contains 70 microprocessors. A PC has just one. It has 35 individual control units - black boxes by another name - and they all talk to one another via three Control Area Networks (CAN) working at 500 kilobits/sec, and one superfast fibre-optic serial network operating at 4.2megabits/sec. A conventional low-speed serial network functions at just 9.6kilobits/sec. At any one time, the quantity of CAN messages in use around the car can number over 2000.
This electronic dialogue is important because all the various features on the car need to know what the others are up to as rarely does one have no impact on any of the others. For instance if the windows are being lowered, this is information that is likely to be of interest to the security systems. Another example is the information provided by the self-levelling sensors in the suspension is also of use to systems such as the ESP to help it constantly monitor the car's progress and the automatic headlight levelling to keep the beam at a constant pitch.
This system also helps simplify operations as it saves the same information being gathered by independent systems. One example of this is that responsibility for measuring vehicle speed has been allocated to the ABS sensors but this information is also used by the powertrain network for the engine management and transmission.
The easiest way to understand how the Bentley Continental GT's internal communications are configured is to imagine the networks as a huge notice board upon which all contributing systems post information as they receive it. Once there it can be seen by all other systems and, if need be, acted upon accordingly.
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