On Wednesday, NASCAR announced a notable change to the NASCAR Cup Series Rule Book ahead of the 2024 season, which pertains to the rules package being utilized for the majority of short track and road course events.
After the feedback provided by drivers after several multi-day test sessions, NASCAR has elected to run a simplified diffuser at a majority of tracks measuring one mile or shorter, as well as all of the road course events.
The major change for the upcoming season is a simplified rear diffuser with fewer vertical strakes. That configuration allows downforce to be cut by keeping the engine panel strake-free and retaining splitter stuffers from last year’s aero package on short tracks.
To counteract the loss of downforce, competition officials have decided to introduce a slightly taller rear spoiler, which will sit at three inches in height for the upcoming season, rather than the two-inch height used in 2023.
These changes will not come into effect until the fourth NASCAR Cup Series event of 2024 at Phoenix Raceway, with NASCAR electing to not put these rule changes into effect for the pre-season exhibition event at the Los Angeles Memorial Coliseum.
“At the test, we noticed an improvement in traffic. The car did not lose rear downforce when it yawed, which is an issue we fight with the current car. The drivers would be able to slide around more on the short tracks and really have to be less careful about putting power down,” said Dr. Eric Jacuzzi, NASCAR Vice President of Vehicle Performance. “We felt that would be a benefit, and that was the big takeaway from the driver feedback. At the test, they felt they could really tell that it was more forgiving. They felt they could slide the car.”
The implementation of this new package will come with a pair of additional tests – one in the wind tunnel on February 13th to ensure aero parity among the three manufacturers, and another on February 20th at Phoenix Raceway to collect data.
These parts are expected to be available to teams early next month, while Jacuzzi also mentions that the new simplified diffuser would signal cost-savings for the teams.
At this time, the new short track/road course aero package will not be in effect for events at Bristol Motor Speedway or Dover Motor Speedway, barring any changes desired after the usage of the new package at Phoenix, Richmond, and Martinsville in the early portion of the NASCAR Cup Series season.