Chiron Uncovered

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BEN MILLER pics JOHN WYCHERLEY

Secrets revealed: The Bugatti Chiron’s incredible engineering tale

THE more things change, the more they stay the same, and in Bugatti’s unspeakably indulgent world of money, speed and luxury that means one thing: that engine. For while the Chiron – the car that will grasp Veyron’s baton and run with it to 500 units costing at least AU$3.5 million apiece – is a new car by every significant indicator of these things (monocoque, coachwork, systems, performance, driving dynamics) there’s an old friend bolted to its composite rear bulkhead.

Chiron’s Judgement Day came long before Ferdinand Piëch’s departure from VW’s supervisory board, before Dieselgate. It was May 2012 when key VW Group minds met in Spain to sign off or kill off a number of projects.

In a duotone split of polished aluminium and deep Atlantic blue, the prototype Chiron awaited its turn with Piëch, the man whose infamous inability to stomach negative answers had snatched Veyron from oblivion a decade earlier. The bad news?

Piëch wasn’t mad about the frontend styling, and suggested changes.

The good news? The powertrain met its primary performance objective: 1100kW, nearly 224kW up on the 2.5sec-to-100km/h Veyron Super Sport. Thanks to the W16’s apparently limitless potential for power, Molsheim could embark on another era of fabulously exclusive performance engineering.

That remarkable power hike comes courtesy of some good old-fashioned hot-rodding. The crankshaft has shed 1.4 kilos, in part to allow a move to 16 new, much stronger titanium conrods and four enormous turbochargers that are 30 per cent bigger than even the coiled brutes that force-fed the Super Sport. Their vast dimensions, which usually means epic turbo lag, have forced a switch to sequential charging. A pair of servo motors work valves in the manifolds, effectively blanking off one turbo on each side in low-demand conditions for immediate response, and opening them as required for peak boost (a heady 27psi) when the devil rides.

New big-bore intake and exhaust systems in weight-saving carbonfibre and titanium work to deliver the turbos’ charge unimpeded, and scavenge the combustion chambers of exhaust gases as efficiently as possible. Power is up and so too is torque, with a gut-wrenching peak of 1600Nm available from just 2000rpm.

Chiron’s transmission is fundamentally the same seven-speed Ricardo DCT, necessarily uprated (new selector forks, new hubs, a revised lubrication system and new oil, given a fighting chance of staying somewhere useful under duress by carbonfibre anti-surge baffling), and with a bigger crown wheel, stronger universal joints and stouter driveshafts. A reinforced six-plate clutch has, after some 483,000km of testing and sufficient launch-control starts to savage 200 sets of bespoke Michelins, proven itself up to the job.

A powerhouse then, though head of engineering Willi Netuschil and his team are adamant that Chiron also eclipses Veyron on the rate

“In the Veyron full throttle was ‘ooof’. In Chiron it is ‘urgh’ – it gets you right here, in the stomach.”

and linearity of its throttle response.

“Without sequential turbocharging the delay would have been significant, unacceptable,” Netuschil explains.

“With it the response is very fast and completely linear – each change in the angle of the accelerator pedal gives a corresponding increase in power. This is very important in a car with this much power, this much torque.”

Does it feel faster? Christophe Piochon, Bugatti’s head of production and a man who stopped logging his Veyron miles four years ago at 40,000, smiles and nods: “In the Veyron full throttle was ‘ooof’. In Chiron it is ‘urgh’ – it gets you right here, in the stomach.”

And so that mighty engine went on dictating its requirements, issuing challenges. For design director Achim Anscheidt it meant elegantly balancing one almighty thermal equation, and almost entirely opening up the rear of the car.

“We have this dramatic cutaway rear now, reminiscent of the Porsche 918 and McLaren P1,” Anscheidt explains.

“This was absolutely necessary for us. It was so challenging, to get rid of the heat that comes with such performance. Now it is sucked from the engine and from under the rear wings instantly, helped by the more tapered glasshouse.” Spanning this great void is the Chiron’s greatest moment of visual theatre, a fullwidth LED rear light bar set in a single enormous arc of three-dimensionally sculpted aluminium. “One piece,” Piochon grins. “You can imagine the size of the block we start with.”

Linked to the need to get cool air into the car and hot air out is Chiron’s defining design element, an endless, elegant curve picked out in polished aluminium that runs low along the side of car before tracing a curve up, around the rear of the doors and forward to the base of the A-pillar.

“You see this curve, the Bugatti line, again and again in the old cars and even in Ettore’s signature,” Anscheidt continues. “But to use it on these grounds alone would have been too romantic for such a technical car: form must follow performance. From our aerodynamic evaluations we knew that the air lower down the side of the car was low in pressure and turbulent. The air higher up, at the side window, is less turbulent and at a higher pressure, so the Bugatti line defines a highly effective air intake.”

The Bugatti line’s a good example of the Chiron design philosophy generally; a familiar form, all-new execution. The face is cleaner than before; a broader nose, interrupted by fewer shut lines and colour splits.

Venting abounds, feeding the front brakes (no fewer than three ducts feed each disc and caliper) and the bigger main radiator, but they’re cleanly incorporated, as befits Bugatti’s eccentrically luxurious take on ultrahigh performance. The surfaces are taut where Veyron’s were generous, pulled at times into spines and ridges that echo the still-startling Type 57 Atlantic of the 1930s.

“We have a new form language,” Anscheidt says. “Now we have more extreme forms to define the body, with sharper lines thanks to the carbonfibre tooling we have perfected.” That being, air bladders to force the pre-preg carbon into the trickiest of shapes, and a multi-part mould requiring disassembly to extract each newly formed panel in the case of the fiendishly splined rear deck.

Anscheidt’s labours clothe a new chassis that, according to Bugatti president Wolfgang Dürheimer, is Chiron’s crowning glory. “The steering, the lateral acceleration, the high-speed stability, ride comfort on cobbled streets – the improvements in all these areas are considerable.

A Veyron owner will notice these immediately,” he says. Just as the Super Sport was noticeably more alert, responsive and understeerresistant than the original Veyron, so it’s claimed Chiron is a keener car should the mood strike. “Veyron had more understeer. Chiron breaks from the rear,” smiles Piochon, and

he should know. Indeed, select the Handling drive mode (one of five, the others being low-speed Lift, the default EB Auto, ultra-stable Autobahn – the default north of 180km/h – and all-out, key-armed Top Speed; each tweaking ride height, damping, power distribution, aero, steering, ABS and stability control) and Chiron will set its Haldex all-wheel drive and rear diff for ‘easy drifts’, so you can make like a Focus RS with four times the power.

The foundation of this dynamic re-invention is a new carbonfibre monocoque. Outwardly similar to the outgoing tub, it’s actually entirely new, wrought from a light but stiff laminate of carbonfibre inner and outer skins sandwiching a honeycomb core. A new front-end package (laiddown main radiator and a smaller, much lighter lithium-iron-phosphate battery under the passenger cell) has freed up the space for a modest luggage compartment. Suspension is by bespoke Sachs dampers that use motors to continuously optimise their behaviour, responding in less than 6ms. Multi-compound bushes and a trick, all-carbonfibre front anti-roll bar claim to bring a new level of refinement with no unwanted slop. AP has engineered an all-new braking system, with vast (420mm) carbon-ceramic discs and one-piece (for less twist and a firmer pedal feel) weight-optimised calipers (complete with eight titanium pistons up front) controlled by a new ABS module.

Intricate heat shields protect the wheels and tyres from the brakes’ thermal fallout, while the rubber itself (285/30R20 front and 355/25R21 rear Pilot Sport Cup 2) ditches Michelin’s Pax run-flat system for mildly less expensive servicing.

“With the Super Sport our engineers thought they’d tickled this car to the Holy Grail, but we have surpassed that with Chiron,” Dürheimer says. “Our customers are hard to please – they have on average 63 cars – but when they experience the Chiron they will not be able to say no.”

Early sales figures would suggest Dürheimer’s half-right. Of 200 or so key clients solicited thus far, 160 – nearly one third production run – have with money-down the incremental increase speed, from the Super Sport’s 415km/h to Chiron’s limited) 420km/h carries disappointment, the buying elite doesn’t unduly concerned. After all, opportunities to safely teleport from in less than 2.5 seconds mercifully less rare than the right for 415km/h-plus cruising. limiter lifted, the numbers suggest 462km/h is within grasp.

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Wasn’t Galibier meant to be the next Bugatti?

FIVE years ago, when Wolfgang Dürheimer first joined Bugatti from Porsche, he was keen that the Galibier limousine should follow Veyron: a front-engined four-seater using the W16 and a version of the coupe’s DCT/fourwheel- transmission. At that stage much was still vague – dimensions, carbon or aluminium construction, mild hybridisation – but the car looked to be a certainty. Less than two years later plans were shelved and Molsheim’s focus shifted to Chiron. The appetite to deliver Galibier remains – Dürheimer is extremely keen, seeing the car as one of which Ettore Bugatti would wholeheartedly approve – but the project must wait. “It was a question of being ready to go on a project of that scale,” explains design director Achim Anscheidt. “It would have to be the ultimate car of its type, the ultimate four-seater, and it was perhaps too soon for us.”