Based on Chevrolet comments the C8 has a chassis torsional rigidity, or stiffness, of around 19,000 NM/degrees. Fixed roof Lamborghinis, McLarens and Porsches are all around 40,000 NM/degrees. These numbers show that there is an opportunity to improve the C8.
The C8 chassis is built around a central tube assembly highlighted below that ends at the engine, creating a gap in the structure in the engine bay, see picture on the right. The X brace fills that gap. The X Brace is a large truss to reinforce the chassis. As the Lead Chassis Engineer for the C8, Ed
“The trick for torsional stiffness is that you’ve got to get the load through the tunnel
and back to the shocktowers and it is hard with the engine there..." Ed Moss
The X brace accomplishes this "trick", by transferring load from the shock towers to the rear bulkhead and central tunnel.
By attaching to the shock / strut towers the X brace directly reinforces the body, reducing flexing and improves rigidity by over 8%.
The X brace was designed to be many times stronger than the forces or load it will ever see, even on the track. The X brace was designed through 100’s of iterations to achieve the function of strength while also maintains the aggressive angular design language of the C8’s F22 fighter design language. Once the design was “complete” it was run through “Stress Analysis” software that exposed weaknesses. The design was again modified to eliminate all areas of stress and flex at levels far exceeding required loads. The rear brackets required the most engineering due to the complex shape and angle of the loads. Attaching at other locations was evaluated, however attaching anywhere but at the struts would not have delivered improved performance.
The X brace was then placed on an F1 chassis analysis machine. My C8, shown below was tested with and without the X brace. The X Brace improved torsional rigidity by over 8%. Also, the maximum load on the brace was captured for later analysis and product testing.
Track testing confirms that the rigidity significantly improves the lap times, feel and control of the C8. Summer 2023 testing showed a 1% improvement in lap times for a 2023 Z07, which is a very significant impact on track performance. Drivers report improved control in the apex of turns an rapid lateral transitions. The X Brace rigidity can be felt on aggressive street driving as well, the car is more solid, settled and controlled. https://www.youtube.com/watch?v=ImpYWVPnV
Testing and final validation
Each Chassis Brace is personally tested by the Founder and Lead Engineer David McCauley before shipping. The braces are placed on a fixture with a load cell and tested at over 5 times the maximum load that the brace will ever be exposed to.
The X brace was designed for the function of making the C8 a better handling supercar, and the beautiful aggressive form follows that function.
All of the machined components are made from Stainless Steel, which is more expensive and durable than aluminum. Which means they will not corrode, fatigue or crack under years and years of use like aluminum. The tubes are made of six (6) layers of solid carbon fiber, the colored versions have one layer of fiber glass for coloring (Red, Blue or White/Gray). The X brace was designed for easy installation and does not require modifying the car in any way. Two (2) bolts and four (4) nuts are removed, the X brace is placed into position, and the six (6) factory fasteners are reinstalled. Overall, the X Brace provides a relatively inexpensive customization that looks great and significantly improves the performance of the car.