One big change from the Regera to the Jesko that most people missed
Towards the end of 2019, the automotive world got a quick sneak peek at the new Corvette C8.R race car. It looked aggressive and mean, fitting for the CX.R line of race cars. Then someone egged on one of the GM engineers to start it up. When he flipped the ignition, a sound resonated from the exhaust that was unfamiliar to Corvette Racing fans. This sound was shrill and sharp, not thunderous like the C7.R. Something was clearly different with the C8.R.
On December 16th, 2019, Koenigsegg shared with us one of the first videos of the Jesko being driven. At low speeds this car sounded pretty typical. A thick low RPM rumble and some spooly boi noises, par for the course for Koenigsegg. Then Christian Von Koenigsegg suggested the cameraperson stand behind the Jesko while he revved the engine....
This sound wasn't typical of a Koenigsegg. It, like the C8.R, was a shrieking, ferocious sound more akin to a mountail lion's scream than a than a tiger's roar. Why doesn't it sound like the Regera or the Agera that came before it?
90 vs. 180 degrees
The reason for the difference in exhaust note between the Regera and the Jesko is the change in the crankshaft, and therefore a change in the way the exhaust gases leave the engine. In the Regera and other previous Koenigseggs, the engine has a cross-plane crankshaft, resulting in uneven exhaust scavenging because each bank fires twice in a row once per cycle. This leads to a muscular exhaust note similar to an AMG GT or a Dodge Challenger.
Example of a cross-plane crankshaft firing order:
The Jesko's redeveloped engine now uses a flat-plane crankshaft which allows for even exhaust scavenging. This gives you a smoother exhaust note and allows the engine to rev higher due to the reduction of rotating mass. The Jesko sounds more like a Ferrari 488 Pista or a Mclaren 720S, which both have flat-plane crankshafts and are turbocharged.
Example of a flat-plane crankshaft firing order:
The result of this change is a much more exotic engine note than before. I wasn't the biggest fan of the way previous Koenigseggs sounded. They were muscular and throaty but muted like the Veyron and Chiron. I didn't feel like that sound really matched the way these cars look, so I'm happy they went with a flat-plane crank. I'm so excited to hear one driving full tilt sometime soon!