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NASCAR to Implement Simplified Rear Diffuser, Taller Spoiler for 2024 Short Track Package

The new aerodynamic package will hit the track for the first time at Phoenix Raceway in March, and be in effect at all short tracks and road courses in 2024 -- except for Bristol and Dover.


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NASCAR has made notable changes to the aerodynamic package for NASCAR Cup Series events on short tracks and road courses for 2024, the sanctioning body officially announced on Wednesday.

The updates, which will make their first on-track appearance at Phoenix Raceway in March, include a simplified rear diffuser with fewer vertical strakes, the removal of engine panel strakes, and the same splitter stuffers as last year.

To counteract the loss of downforce created by these new rule changes, competition officials have decided to make the rear spoiler slightly taller for 2024, sitting at three inches, instead of the two-inch splitter height previously used in 2023.

The aforementioned changes come as a result of feedback from drivers, who got the opportunity to make laps in several multi-day test sessions, all with the end goal of designing a better aerodynamic package for short track and road course events in the NASCAR Cup Series.

NASCAR Cup Series teams will not utilize this new configuration for the pre-season exhibition event at the Los Angeles Memorial Coliseum, as teams will likely not have the needed parts until early next month, creating an impossible turnaround time for the February 4 event.

"At the test, we noticed an improvement in traffic," said Dr. Eric Jacuzzi, Vice President of Vehicle Performance for NASCAR. "The car did not lose rear downforce when it yawed, which is an issue we fight with the current car. The driver would be able to slide around more on the short tracks and really have to be less careful about putting power down. 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."

As a result of the late-stage implementation of this package, a pair of test sessions have been added to the docket by the sanctioning body. First, a wind tunnel test on February 13th to ensure aero parity among the three manufacturers. Then, a second test, at Phoenix Raceway on February 20th, to collect data with wheel force cars.

This new road course and short track package will be put into practice for all races at tracks one mile or less, except for Bristol Motor Speedway and Dover Motor Speedway, barring any changes desired after the opening quarter of the year.

Photo Credit: Johnathan McCoy, Racing America

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