NASCAR took the hood louvers from all four Hendrick Motorsports cars for further examination after practice Friday afternoon at Phoenix Raceway.
An unspecified potential issue with the louvers was discovered in the garage but all four teams — the Nos. 5, 9, 24, and 48 — were permitted to participate in practice. The 50-minute practice was the first time NASCAR Cup Series teams worked with the new short-track aero package.
Kyle Larson and the No. 5 team topped the speed chart at 131.258 mph (27.427 seconds). Alex Bowman and the No. 48 team were third fastest at 131.105 mph. Larson also topped the best 10 consecutive lap average, while William Byron was fifth best in the category.
The parts will be taken back to the NASCAR R&D Center for further evaluation before any potential penalties are handed down.
Louvers are the openings in the hood that were a key component of the Next Gen design to allow for maximum engine performance. The louvers allow for air to exit through the hood for better engine cooling and aerodynamics.