Bugatti Veyron: soon to be the world's fastest production car
By Mike Hanlon
June 1, 2005
June 2, 2005 Ettore Bugatti produced machines that set world speed records for planes, boats, trains and cars, built the most successful racing car in history and the most expensive car in history. The marque has been revived after 50 years and the new car recently exceeded 400km/h in testing. Its engine has 16 cylinders, eight camshafts, four turbochargers, 64 valves and produces 987 horsepower. When the Bugatti Veyron goes on sale later this year it will cost 1,000,000 Euros and only 300 will ever be built. It will also claim the title of the fastest production car in history, exceeding the McLaren F1’s record of 386.4 kmh (240.1mph) which stood for seven years, and the recent record established by the Koennigsegg CCR of 387.87 kmh (241.01 mph). Last month, a prototype Bugatti Veyron was officially measured at over 400 km/h (248.5 mph) at the Volkswagen Ehra–Lessien proving grounds reaching this speed several times and in both directions, as required by official measuring procedures.
Accordingly, after a 50 year hiatus, the Bugatti badge is returning on a car as breathtaking as those which created the legend on the roads and racetracks of Europe prior to WW2. Named after the most famous racing driver of the thirties, Pierre Veyron, the Bugatti Veyron 16.4 will be the fastest and most expensive production car ever produced. It has taken some time to achieve the lofty goals set by Volkswagen, which purchased the marque’s name and then set about trying to build a car over-the-top enough to live up to Ettore Bugatti’s remarkable engineering feats. He produced machines that set world speed records for planes, boats, trains and cars, built the most successful racing car in history and the most expensive car in history.
While the Veyron's power and speed figures are astounding, so too is the acceleration - between 2200 and 5500rpm it makes an 922lb/ft of torque - an outrageous feat and one achieved via F1-style and other bleeding-edge technologies such as having not one but two independent engine management computers for each bank of cylinders, and the electromagnetic injection valves which make it possible to precisely define when and how much fuel is injected into each combustion chamber. This massive mid-range grunt allows the Veyron to accelerate from standstill to 300kmh in under 14 seconds.
But the performance is only one facet of this diamond. The array of unique features within the car are commensurate with the million euro price tag and include a specially designed seven-speed gearbox, an aerodynamic monocoque body complete with fully-panelled undertray and a rear spoiler which changes position according to the speed range of the car.
Even the hi-fi system was designed in conjunction with the body shape. There is nothing ordinary about this car. The innovative W16 light alloy engine develops a phenomenal 736 kW (987 bhp) at 6000/min and is installed in the mid-engine position ahead of the car's rear axle. Because of the W configuration, the 64 valve, 7,993 cc engine remains compact at 710 millimetres long and 767 mm wide, yet still produces a maximum torque of 1,250 Newton-metres with the help of four turbochargers.
Four continuously variable overhead camshafts actuate the valves with settings controlled by a continuous electro-hydraulic system, which takes effect in all engine operating situations and incorporates two computers for each bank of cylinders to maintain the engines correct operating parameters.
There will not be a modified production "street version" with diminished performance according to Bugatti.
Aerodynamic advances have not left behind the characteristic Bugatti radiator grille but to ensure optimum cooling of the W-engine and the brakes, large air intakes are incorporated at the front and a rear spoiler that extends automatically when the car reaches a predetermined road speed aids down-thrust.
The Veyron's specially developed seven-speed gearbox features a sequential gear-shift controlled via paddles at the steering wheel - as per F1 racing cars - and the double clutch system performs gear shifts within a maximum of 0.2 of a second and by-passes the need for a clutch pedal.
The need for tyres capable of handling speeds in the 400kmh region has also led to special research and development - Michelin has created a new type of tyre that has been successfully tested at 440kmh.
The braking system
By attempting to build a car that can run at 400kmh, the goal has influenced every aspect of the car, including putting some stellar demands on the running gear. The carbon-ceramic brake system has been designed with many components that are unique, having been developed in cooperation with partners from the aviation and space industries.
Experiencing the brake system in action is just as enjoyable as experiencing the acceleration of the Bugatti. The addition of the airbrake, an aerodynamic rear-wing braking function which is deployed above speeds of 200 km/h, gives the vehicle deceleration values which cannot be experienced in any other car in series production.
Brake pressure of up to 180 bar
The brake forces are distributed with a maximum of sixty percent on the front axle and forty percent on the rear axle. The system is capable of a brake pressure of 180 bar. Braking to the ABS control range requires 50 to 70 bar in a Bugatti Veyron with standard tyres – a difference of over 100 bar from the top performance of 180 bar, an indication of the high braking potential.
Carbon discs, titanium brake pistons
The carbon disc brakes have a diameter of 400 millimetres in the front (rear: 380 millimetres). The eight-piston monobloc brake caliper weighs only 5.7 kilograms, is reinforced with a centre fin and has four brake pads. Its pistons are made of titanium and are fitted with a stainless steel crown and ceramic heat shield. The pad friction area totals “4 x 80 cm2”. The grooves in the discs for air cooling are not straight but have a turbine-shaped structure so that they are able to draw in cooling air while the vehicle is in motion.
From 310 km/h to 80 km/h and back repeatedly without fading! In addition, the front disc brakes, which are have higher demands placed on them, are maintained at a constant ideal temperature even under maximum loading by a completely new type of dynamic pressure cooling. An example from the prototype trials: during a brake fade test with 1.0 g* repeated braking from 310 km/h to 80 km/h (acceleration from 80 km/h to 310 km/h + subsequent braking in only 22 seconds per cycle in total!), a thermal equilibrium was achieved after braking for the twentieth time – even then, the brake fluid temperature stayed below the defined 220°C level and the top surface of the discs below a 1 000°C limit. The technical structure of the air supply is unique in this context:
Unique dynamic pressure cooling
To achieve the greatest possible dynamic pressure and therefore make use of high volumes of air, the cooling air stream enters a duct located in the best possible position in the front of the car. On the way to the brakes, the air also cools the front differential of the four-wheel drive and the battery as it flows past. The air stream then flows from the centre of the vehicle towards the carbon discs and pads. Just before the air flows around both of these it meets a unique component which guarantees the stability never before achieved in this type of brake system: a FroSt swivel bearing (Flow Rotating System) with a special air duct with a tapering spiral and allows for a large amount of air flow in a narrow space.
The air flows into the swivel bearing and into the increasingly small space, accelerates with a swirl towards the rotating brake discs and is then released back into the open air through the turbine-shaped vanes inside the discs as a turbulent current. A side stream is also directed through small ducts in the stainless steel crowns of the disc on the surface of the disc and through an air outlet in the swivel bearing directly onto the caliper and the pads.
Rear-wing becomes airbrake in 0.4 seconds
As previously mentioned, the rear wing functions as an airbrake, optimising braking performance at speeds above 200 km/h. The wing is then angled at 70 degrees in less than 0.4 seconds, which has several consequences. Firstly: the rear axle downforce is increased, therefore improving the distribution of the brake force between the front and rear axles. Secondly: air resistance is increased, as in an aeroplane when landing. The airbrake alone produces a maximum deceleration of 0.6 g* at high speeds. It is activated via the brake pedal. The wheel brakes themselves achieve – with standard tyres on appropriate road surfaces – deceleration values of around 1.3 g*. With full brake application at 400 km/h, the Bugatti Veyron would come to a standstill in considerably less than 10 seconds!
Handbrake with ceramic brake pads.
Another innovative detail is the handbrake. Bugatti has installed a separate brake caliper here, as is customary in sports cars. However, the fact that this component is operated electronically and has full ABS function together with a parking brake auto release system makes it unique. In the highly unlikely event of a fault with the main brakes, the driver would be able to bring the Bugatti Veyron to a safe and stable stop below a certain speed limit, even on a surface with varied friction values (for example, ice on the right, dry as a bone on the left). What is more, this caliper is fitted with wear-resistant ceramic brake pads designed to last for the complete life-time of the vehicle.
ESP as a safety and dynamics factor.
It is clear that Bugatti has designed an ESP brake system which corresponds to the high performance reserves of the Veyron completely. Thanks to a complex and intelligent mechatronic system to activate the rear differential lock and the front four-wheel drive, the Bugatti Veyron is entering driving dynamics territory still uncharted even by racing cars. A progressive ESP system ensures that the exceptional sports car can still complete its laps safely even if the dynamic limits already appear to have been exceeded. On the one hand, it is based on familiar features; on the other hand, it has numerous new functions developed specifically for the Veyron. And this is true of the full speed range! A crucial factor in this is that the brake electronics do not restrict the outstanding driving performance, but rather they improve the lap times which can be achieved on the world’s really fast and appealing circuits.
All hail the Bugatti Veyron – it would be an injustice to just look at the top speed figure, as this car is an extraordinary feat of engineering.
The name Bugatti is one of the most charismatic in the history of motoring for good reason. An excellent overview of Bugatti history can be found here and also at the official Bugatti web site.