How titanium 3D printed parts helped the Bugatti Bolide achieve weight-to-power ratio of 0.67 kg/PS
With the technological concept of the Bugatti Bolide, the french luxury car manufacturer is now providing the answer to the question “what if Bugatti built a radically light vehicle around its iconic 8.0-liter w16 engine?” The experimental study of the Bugatti Bolide is a track-oriented hyper sports car featuring a w16 engine derived from series production as powertrain combined with a minimal body for maximum downforce. It, therefore, promises to offer the ultimate Bugatti performance kick.
At the same time, the Bugatti Bolide is the most extreme, uncompromising, fastest and lightest vehicle concept in the company’s recent history – with an incredible weight-to-power ratio of 0.67 kg per PS. This is made possible by the combination of the W16 engine with 1,850 PS and a vehicle weight of just 1,240 kilograms. The Bugatti Bolide achieves figures that are almost on par with Formula 1 while its top speed is well above 500 km/h – without compromising maximum handling and maximum agility. The Bolide takes 3:07.1 minutes to complete a lap of Le Mans and 5:23.1 minutes to get around the Nordschleife.
1,850 PS and 1,240 kilograms
In order to achieve a dry weight of 1,240 kilograms, all the stops have been pulled out with regard to the materials and production processes used, both in terms of what is currently feasible and what will be possible in the future.
All the screw and fastening elements of the Bolide are made completely out of titanium. In addition, hollow, thin-walled functional components made of an aerospace titanium alloy are used in many places. These, of course, are 3D printed – and are extremely thin with wall thicknesses of up to 0.5 millimeters. However, they are still very stable with a tensile strength of 1,250 newtons per square millimeter.
Hybrid components, such as the 0.5- meter-long auxiliary drive shaft, combine wound high-strength and ultra-stiff carbon fibers with 3D printed titanium end fittings and can withstand a continuous operating temperature of up to 260 degrees Celsius. In this example, this reduces the weight by around half to 1.5 kilograms and, due to the reduction of the rotating masses, increases the revving ability of the engine at the same time. The forces acting on the front and rear wings are transferred by ultralight but very solid titanium elements. They weigh a mere 600 grams at the front and an astounding 325 grams at the rear.
Bugatti is not new to using 3D printing in final parts. The company already produced several components by AM, including brake calipers and spoilers.
The idea – what if?
“Bugatti stands for the continuous quest for technological innovations – in alignment with the company’s brand values of excellence, courage, dedication. And Bugatti never stands still. We are perpetually aiming for new and exciting goals, and the question that we always keep in mind is: what if?” said Stephan Winkelmann, President of Bugatti. “We asked ourselves how we could realize the mighty W16 engine as a technical symbol of the brand in its purest form – with solely four wheels, engine, gearbox, steering wheel and, as the only luxury, two seats. Important aspects of our considerations were fine-tuning our iconic powertrain without any limitations as regards the weight-to-power ratio. These considerations resulted in the Bugatti Bolide. An uncompromising experiment, a thoroughbred, a Pur Sang that, in its brute exclusivity, impresses above all with high performance, low weight, and a driving experience in a whole new dimension. Driving the Bolide is like riding on a cannonball.”
“In terms of technology and organization, the Bolide was one of the most ambitious projects of my career,” said Frank Götzke. After playing a crucial role in the development of the Veyron 16.4 and the Chiron, the engineer was also responsible for the technical concept of the Bolide. In only eight months, he created a completely new vehicle around the well-known Bugatti W16 all-wheel powertrain, which was highly modified for the project.
The 8.0-litre W16-cylinder engine with 1,850 PS and 1,850 newton-meters of torque is at its heart. Bugatti has designed the drive specifically for use on the racetrack and has optimized the engine and gearbox in particular for higher engine speeds. Among other things, this includes dethrottling the intake and exhaust system to achieve an even faster, more spontaneous, and extreme response characteristic. The four newly-developed turbochargers are fitted with optimized blades in order to build up more boost pressure and power at higher engine speeds. In order to achieve optimum lubrication even under extremely high centrifugal forces, the oil circuit, oil pressure, check valves, baffles, oil tanks, oil reservoirs, and pump design of the dry-sump lubrication have been optimized. The weight of the drive system is also significantly reduced at the same time.
Instead of water-to-air intercooling, the Bugatti Bolide has air-to-air intercooling with water pre-cooling for optimal performance on the racetrack. The inflow takes place from the front via one internal and one external air duct on each side of the vehicle. The two water coolers, which are arranged in front of the front axle, provide a more effective radiator system in terms of flow than is customary even in Formula 1. Three air-cooled oil coolers for engine, transmission, and differential with water pre-cooling reduce the temperature even on dynamically demanding race laps. Newly developed and hybrid carbon titanium turbofan radial compressors ventilate and cool the high-performance racing brake system.
A light monocoque made of carbon
The Bugatti team developed a light monocoque made of carbon around the drive. The integral front end flanged to it is also made of high-strength carbon fibers, as are the fully aerodynamically effective underbody and the monocoque itself. The single-fiber tensile strength of the fibers used is 6,750 newtons per square millimeter, the single-fiber stiffness is 350,000 newtons per square millimeter. These represent figures that are only reached in the aerospace industry. The rear frame, designed as a welded steel assembly, offers a maximum tensile strength of 1,200 newtons per square millimeter, despite a wall thickness of only 1 millimeter – this is made possible by the use of high-strength stainless steel, which is otherwise only used in aviation.
With an overall height of only 995 millimeters, the Bugatti Bolide is exactly the same height as the historic Bugatti Type 35, depending on the steering wheel and truncated windscreen, and about 300 millimeters flatter than the Chiron. The wheelbase is 2.75 meters and the width 1.99 meters. Like in an LMP1 racing car, the occupants fold up the doors that are hinged at the front at an angle, sit on a sill that is only 70 millimeters wide, as in a Type 35, and then position their feet in the interior. Thanks to a sidewall that is about 150 millimeters lower than that of the Type 35, the procedure is quick and easy – for drivers up to a body height of 2 meters.
Quintessence of form
The experimental study of the Bugatti Bolide is also a very special project for Achim Anscheidt, Director of Design at Bugatti. “In my 16 years at Bugatti, I have never worked on a more extreme concept.” The design of the Bolide is radically tailored to the idea of lightweight construction, and the design principle therefore follows on from the overriding goal of achieving a fascinating weight-to-power ratio of 0.67 kilograms per PS.
The dramatic effect of the overall proportions is made clear by the aerodynamically favorable overall height of only 995 millimeters. The driver’s ultra-sporty seating permits the low-slung shape of an automotive low-flying aircraft. It is therefore not surprising that the appearance of the Bugatti Bolide invokes the so-called X-planes of aviation history and shows a clear X signature from every perspective. It is indirectly reminiscent of the Bell X-1 jet aircraft which was flown by Captain Charles “Chuck” Yeager in 1947, the first person to break the sound barrier at Mach 1.06. The Bugatti Bolide “X-periment” has the shape of an aerodynamically optimized, uncompromising racing car and offers ultra-sporty, superlative performance – with no hint of luxury.
The Bugatti Bolide is the unrivaled technological concept of a track-focused Bugatti hyper sports car. The combination of 1,850 PS and 1,240 kilograms dry weight ensures an unbelievable weight-to-power ratio. This puts the Bolide with its W16 engine at the absolute pinnacle in terms of combustion engines used in automotive engineering. “For the first time, we are showing what the W16 engine is really capable of. We have freed the vehicle of all baggage and have illustrated and combined the engine with the lightest possible chassis to create the ultimate Bugatti and to ensure the ultimate driving experience. With the Bolide, we are presenting our interpretation of a Bugatti track car of modern times to Bugatti enthusiasts all over the world and finally make their most fervent wishes come true,” explained Winkelmann.
Whether the Bugatti Bolide will go into series production, has not been decided yet. AM will be now able to help there too.