In August 2019, the Bugatti Chiron Super Sport 300+ became the first production car to break the 300-mile-per-hour speed barrier – reaching a top speed of 304.773mph (490km/h).
This special-edition Bugatti is based on the standard Chiron, but extensively tweaked to be able to reach higher speeds.
The car underwent modifications to its body, engine, and chassis in order to make “traveling at such extreme speeds safe, comfortable, and reliable”.
Bugatti engineers fine-tuned the Chiron Super Sport to find the optimum aero balance, seeking a low drag coefficient but also high downforce.
Only perfect airflow will keep “harmful turbulence at bay”, and the Chiron Super Sport was therefore given new air curtains at the front to decrease pressure losses and resistance.
“Additional air outlets at the front wheel arches help balance the aero loads even further,” said Bugatti.
The grille was modified to allow 8% more airflow than in the standard Chiron, while the front diffusers at high speed are positioned more horizontally to guide air away from the wheel arches.
More focus was put into the wheel arches, with nine cylindrical outlets connected by carbon air-guiding channels placed at the top of the arches to achieve the perfect aero balance.
This increases downforce without creating extra resistance, generating 20kg-30kg of additional downforce at 380km/h.
Furthermore, the front wing of the Chiron Super Sport was handcrafted and weighs arpproximately 4kg, while complying with “global safety regulations regarding pedestrian and impact protection.”
At the rear, the record-breaker sports a “Longtail” body – making it 25cm longer than the Chiron – along with a larger wing and diffuser.
The longer body assures smoother airflow and a smaller break-away area, while the positioning of the larger diffuser and wing achieves the optimal balance between lift and drag.
The 8.0-litre, W16, quad-turbocharged engine in the Chiron Super Sport was improved with strengthened pistons and a stiffer control spring that allows more efficient oil flow.
This increased maximum output by 73.5kW to 1,177kW, as well as maximum engine speed by 300rpm. The 1,600Nm of torque is also available from 2,250rpm to 7,000rpm, compared to 6,000rpm before.
Bugatti then strengthened multiple components, such as the cylinder heads and valve springs, to withstand the increase in vibration and output.
“Apart from higher rpm, the increase in performance is also a product of optimized and newly developed turbochargers,” said the company.
The turbos feature larger compressors and turbine wheels, with revised blade geometry enhancing thermal efficiency.
“At full load, 4.8 tons of air flow through the four turbochargers every hour.”
The seven-speed, double-clutch gearbox was also given longer gears and now shifts from sixth to seventh gear at 403km/h.
Additional “cold air circles” and air inlets on the undercarriage then allow the system to handle exhaust-gas heat of up to 850 degrees celsius.
Bugatti redeveloped the chassis of the Chiron Super Sport with a focus on its newfound high-speed performance and aerodynamics.
The rear axle spring rate was increased by 7% compared to the Chiron and the electronically-controlled chassis and damping rate were improved.
“Within six milliseconds, almost in real-time, it adjusts the dampers and adapts to the vehicle’s movements.”
The new setup drives all four wheels via Michelin Pilot Sport Cup 2 tyres and aluminum, five-spoke, 20-inch and 21-inch wheels that offer more rigidity and smoothness above 420km/h.
These enhancements make it possible for the Chiron Super Sport to accelerate from 0-200km/h in 5.8 seconds and reach 300km/h in 12.1 seconds.
From 0-400 km/h, the Chiron Super Sport takes a mere 28.6 seconds.
“This makes it 12%, or four seconds, faster than a Chiron.”