Speed freak

Bugatti Bolide takes the Chiron platform to the extreme. Does a crack at the Nürburgring track record beckon?

THE BUGATTI CHIRON HAS SPAWNED countless special editions since its launch, from the retro-rehash Centodieci to the record-breaking Super Sport 300+. Now Bugatti has taken things a step further by creating the Bolide, a track-orientated model that wraps a bare-bones, lightweight body around the Chiron’s mighty W16 powertrain.

Beyond the marque’s trademark horseshoe grille the result bears little resemblance to its road-going siblings. Sitting just 995mm tall, the design is intended to be reminiscent of the Bell X-1 aircraft in which, back in 1947, Captain Charles ‘Chuck’ Yeager became the first person to break the sound barrier. A complex, stacked wing set-up can be found at the rear, with a central fin mounted on the engine cover for increased stability, while mammoth 400-section Michelin slicks are also clear to see; for reference, the Chiron uses meagre 355-section rear rubber.

Still driving all four wheels is Bugatti’s 8-litre quad-turbocharged W16, which on 110-octane racing fuel can now produce 1824bhp and 1364lb ft of torque – up 345bhp and 184lb ft over a standard Chiron – for a quoted 2.17sec 0-62mph time and top speed in excess of 310mph. The Bolide is also said to go from 0 to 249mph and back to rest in just 24.64sec, 6.84sec quicker than Koenigsegg’s Regera.

To ensure the 16-cylinder engine can withstand the toils of a track session, Bugatti has optimised its cooling and oil systems whilst fettling all four turbos to produce more boost at higher engine speeds. Three air-cooled oil coolers are employed to help keep the engine, transmission and differential within suitable operating temperatures, and there’s a water pre-cooling system to give a helping hand.

The Bolide’s real party piece is its 1250kg dry weight – astonishing when the powertrain weighs nearly 500kg alone. To streamline weight, air-to-air intercooling is utilised instead of water-to-air, while 3D-printed titanium components, a wound carbonfibre driveshaft, forged magnesium wheels and a stripped cabin all contribute too. Combine this weight figure with the Bolide’s 1824bhp output, and you get an unrivalled 1483bhp-per-ton dry power-to-weight ratio.

Suspension is of a pushrod design with the horizontal dampers visible through apertures in the bonnet. Extreme aerodynamics were also high on the agenda, with a peak downforce rating of 1800kg on the rear axle and 800kg at the front at 199mph. A ‘morphable outer skin’ is also used for the roofmounted intake to reduce drag by ten per cent.

Bugatti hasn’t decided if it will put the model into production, but it has claimed the Bolide will lap the Nürburgring Nordschleife in 5min 23.1sec – just seconds off the Porsche 919 Hybrid Evo’s record time. It would certainly be fascinating to see if it could do it…

FROM ITS ORIGINS AS AN OPEN-TOP, road-legal rival to Caterhams and Ariels, the KTM X-bow has now evolved into an extreme closed-cockpit track-only machine.

Called the X-bow GTX, it uses the familiar carbonfibre-tub chassis engineered and built by Dallara in Italy, but from there the package gets significantly more serious with a 523bhp version of Audi’s 2.5-litre turbocharged in-line fivecylinder engine and motorsport-derived drivetrain components. The extra performance from the engine – which produces 394bhp in Audi RS applications – comes from a new injection system, intake, wastegate, exhaust and ECU. No internals have been significantly changed. Torque peaks at 479lb ft and is sent to the rear wheels through a sixspeed sequential transmission with an electronic shift mechanism that helps strip 7kg from the package’s weight. The clutch has a race compound, and there’s a mechanical locking differential too. KTM has not released acceleration figures but says the car will reach 176mph.

The new bodywork is carbonfibre and is far more aerodynamically efficient than the bodies of the more open X-bow models. It’s also able to support more effective aero kit, which is dominated by a large top-mounted rear wing. There are no doors, so access to the cockpit is via a roof canopy that lifts up and forwards.

Hanging from the carbon tub are a set of

Sachs dampers, manually adjustable for rebound, compression and ride height. The coilover units are mounted in a traditional upright position on the rear axle, but as with all X-bows are in a pushrod layout up front. Unfortunately, due to the new carbonfibre skin, they are no longer visible from outside.

The steering has been switched to a new EPAS system, with three weight settings available, while the traction control and anti-lock braking are also adjustable via a digital interface on the steering wheel. The interior is totally stripped down, with structural carbonfibre exposed throughout the cabin and a roll-cage beneath the canopy.

The braking package is made up of 378mm front discs with six-piston calipers, and a 355mm/fourpot combination at the rear. Five-lug lightweight racing wheels are standard, although centre-lock units are available as an option.

Arguably the most crucial figure on a track car is weight, which for the GTX sits at 1048kg – quite a lot more than rivals from Ariel and Caterham, but the KTM does benefit from an enclosed body and isn’t too far behind in power-to-weight terms thanks to its extra horsepower.

At nearly £250,000 the X-bow GTX is a very expensive toy though, and it also arrives at the same time as another high-end track-only proposition powered by Audi’s five-cylinder engine. Turn the page to find out more…