We sat down with Gregor Gries, Bugatti's Head of Engine Development.
The Holy Trinity. Say these three words and car enthusiasts instantly envisage the Porsche 918 Spyder, McLaren P1, and Ferrari LaFerrari. Three ultimate hypercars with otherworldly power-to-weight ratios and specific outputs. So where does the Bugatti Chiron fit in? An engineering feat in its own right, the Chiron was never meant to compete directly with the Holy Trinity. Since its conception, Bugatti has embraced the dichotomy of both ultra-luxury and pure performance, and the Chiron is no departure.
The Chiron effortlessly achieves ludicrous top speeds all while maintaining a quiet, comfortable cabin with ample accessories and extravagances. To achieve their performance figures all three of the Holy Trinity use a combination of electric motors and internal combustion; however, the Chiron doesn't. The French hypercar is not a hybrid, and Bugatti had good reason for keeping it that way. In an interview with Gregor Gries, head of engine development for Bugatti, we discussed why certain design decisions for the Chiron's powertrain were made and what this also means for the future of the brand. The Chiron is unlike the Holy Trinity in many ways, most notably it produces far more horsepower from its ICE, a monstrous 1500 hp.
"When deciding the engine and turbocharger system, we chose to use four larger turbochargers in a sequential setup due to experiencing very high exhaust gas temperatures of almost 1000 degrees Celsius." As we've discussed in a previous article, the larger the engine displacement, the more frictional surface area and more heat generation. Coupled with the massive horsepower output from the W16, the thermal stress caused by exhaust gasses as well as the power requirements from Bugatti's team led them to not only develop larger turbochargers, but also improve the charge air cooling system as well as the exhaust system to reduce engine back pressure.
"The sequential, two stage, setup ensures maximum acceleration from a standstill without the 'turbo-lag.'" This setup allowed them to deliver an absolutely linear power curve from 2,000 rpm and a huge torque in the low engine speed range. Apart from the power of 1,500 hp the Chiron boasts an incredible 1,180 lb-ft of torque, which is available for over 70 percent of the entire engine RPM range. When developing the Chiron there were no such electric turbochargers available in the size needed for Bugatti's performance goals, and even today electric turbos aren't large enough to meet its requirements.
The Chiron also received a new adaptive chassis for significantly greater agility and driving comfort, completely new high-performance tires tested at aerospace facilities to meet requirements, and new brakes inspired by F1 technology. Last but not least, the ergonomic qualities and the acoustics in the interior have been vastly improved. Bugatti has managed to create a power output that is easily controllable and makes the Chiron so much fun to drive and handle in all kinds of situations, something that cannot be unanimously said about the 918, P1, or LaFerrari. The Chiron can effortlessly achieve its top speed potential, while the more track laptime-focused trio requires a high level of driver skill to unlock their peak performance
The lack of hybrid technology on the Chiron does not imply Bugatti won't find itself developing powertrains with electric motors in years to come. "Our overriding goal is to reach maximum performance and top speed. To accomplish this, we will do everything that is appropriate. If we cannot achieve our future performance goals by using traditional means, alternative technologies will be an option. Then we will make careful choices that will also make our customers happy. For them we build our cars." In the current state of automotive engineering for peak performance, hybrid technology is primarily used as an aid to increased acceleration.
Combustion engines remain the standard when the desire is to develop maximum horsepower. As electric motor technology improves, in both production costs and sustainable max output, it will likely outright replace the combustion engine in performance cars like the Chiron, which aim to take the top speed crown. That day may be sooner than some are willing to admit.