Dr. Diandra: Dissecting Cup’s new short track package


NASCAR will introduce a new short-track package for the Next Gen car this week at Phoenix Raceway. With 30% less downforce, the modifications are intended to improve the disappointing racing at some smaller tracks in 2022.

What’s changed in the new short track package

The most obvious change is the 2-inch spoiler, which is half the height of spoilers for other tracks. The short-track spoiler is also narrower, measuring 58 inches across compared to the 60-inch width used at other tracks.

But the most significant changes are under the car. The Next Gen car creates downforce with a smooth underbody that moves air out from under the car. The lower pressure sticks the car to the track.

The process is largely managed by a part of the underbody called the diffuser. I’ve outlined the diffuser in yellow in the photo below. I also labelled the diffuser skirts and the five strakes positioned between the skirts.

An annotated photo of a Camero from the rear, with the diffuser, strakes and skirts labelled

The next photo shows the full length of the diffuser. You can also see the bolts holding the pieces together. That modular design is largely why NASCAR was able to implement the new package so quickly.

A photo of the diffuser, showing the positions of the strakes and skirts
Photo Credit: Dustin Long

What’s a strake?

A strake, like a splitter or spoiler, is an aerodynamic appendage that forces air to travel over (or under) a car in a very specific way. Andrew McColgan, NASCAR aerodynamics specialist at Chevy’s Charlotte Technical Center, explained that a complete understanding requires invoking the subtleties of vortex dynamics.

So let’s try an analogy. Imagine a stadium or other facility that hosts large crowds. When an event ends, people want to leave as quickly as possible.

If the exit is a single large opening, people move toward it from all directions. They have to slow down or speed up to avoid running into each other. It’s basically a free-for-all.

A better idea is creating lanes that funnel everyone in the right direction. People exiting the stadium see the lanes and adjust their paths ahead of time. You can think of strakes in the same way. They create the fastest way for air molecules to get out from under the car.

The Next Gen’s new short track package removes the three interior strakes (indicated by red arrows in the photos) and shortens the diffuser skirts. That prevents air molecules from exiting the car’s underside of the car as quickly, which decreases downforce.

Despite its location in the rear of the car, the diffuser creates front and rear downforce. Keeping the car balanced required also removing the engine panel strakes, which are located further toward the front of the underbody.

Less downforce equals more driver input

Eric Jacuzzi, NASCAR vice president for vehicle performance, told SiriusXM Radio’s “The Morning Drive” that the new short track package provides about 30% less total downforce relative to the original package. Testing showed little decrease in straightaway speed, thanks to the lower drag from the smaller spoiler. However, corner speeds went down by about 8 miles per hour.

Cars with a lot of downforce can run anywhere on a track the drivers chooses. The shortest way around the track is typically the fastest. Everyone wants to run that line. Passing requires traveling a longer distance, which is difficult when cars are so close in performance.

Josh Wilson, Chevy’s motorsports engineering group manager for NASCAR aerodynamics, explains that cars with less downforce give drivers more options. Drivers will have to experiment with how they enter and exit corners, how quick they hit the brake and throttle, and where on the track they can make their car work.

In theory, that should all lead to more passing and better racing. But will it work in Phoenix?

“I don’t think it’ll be worse,” Bubba Wallace’s crew chief Bootie Barker told me. But he views the Next Gen’s new short track package as a first step. Because the diffuser bolts together, it was relatively easy to remove strakes. More significant changes require single-source suppliers to fabricate enough new pieces to supply all the teams.

Is one car for all tracks achievable?

NASCAR intended the Next Gen to produce great racing at any track using the fewest different rules packages. Superspeedways, of course, require unique configurations. As does the Bristol dirt race.

At the start of the 2023 season, NASCAR added select short tracks to the list of road courses requiring cars to run a wet-weather package.

The desire to minimize the number of distinct rules packages is why the new short track changes will not be used at Bristol or Dover. The banking and speeds at these tracks are too high for the wet-weather package. If NASCAR had added the new aero package to these tracks, teams would have to have tested the short track package with and without the wet-weather package. Each test costs money.

How NASCAR balances the needs of different tracks with the one-car/all-tracks concept remains to be seen.


Sonoma Cup starting lineup


SONOMA, Calif. — Denny Hamlin earned his 38th career Cup pole Saturday at Sonoma Raceway.

Tyler Reddick, who drives for the 23XI Racing team Hamlin co-owns with Michael Jordan, qualified second. Michael McDowell, Christopher Bell and AJ Allmendinger completed the top five.

MORE: Sonoma Cup starting lineup

Ryan Blaney, who took the points lead last week, qualified 31st. William Byron, who is second in the points, qualified 26th.

Chase Elliott, returning from a one-race suspension, qualified 10th. Grant Enfinger qualified 35th for Noah Gragson, who is sitting out this week after suffering concussion-like symptoms from a crash last weekend at WWT Raceway.

Denny Hamlin wins Cup pole at Sonoma


SONOMA, Calif. — Denny Hamlin won the pole for Sunday’s Cup race at Sonoma Raceway, as Toyota took five of the top eight spots in Saturday’s qualifying session. It is Hamlin’s 38th career Cup pole.

Hamlin led the way with a lap of 92.178 mph. Tyler Reddick, who drives for the 23XI Racing team Hamlin co-owns with Michael Jordan, qualified second (92.068 mph), giving Toyota ownership of the front row.

MORE: Sonoma Cup starting lineup

Toyota, which struggled at road courses for much of last year, had only one of its drivers qualify in the top 10 at Circuit of the Americas, the only road course race this season.

Michael McDowell qualified third for Ford after a lap of 92.060 mph. Christopher Bell put his Toyota fourth after a lap of 91.877 mph. AJ Allmendinger was the top Chevrolet, qualifying fifth after a lap of 91.873 mph. Toyota also had Ty Gibbs (91.819 mph) sixth and Martin Truex Jr. (91.736) eighth.

The top two drivers in the points did not fare well in qualifying. Ryan Blaney, who took the points lead last week, qualified 31st. William Byron, who is second in the points, qualified 26th.

Chase Elliott, returning from a one-race suspension, qualified 10th. Grant Enfinger qualified 35th for Noah Gragson, who is sitting out this week after suffering concussion-like symptoms from a crash last weekend at WWT Raceway.

Sonoma Xfinity starting lineup: Kyle Larson wins pole


SONOMA, Calif. — Kyle Larson will start on the pole for Saturday’s inaugural Xfinity Series race at Sonoma Raceway.

Larson won the pole with an average speed of 91.393 mph around the 1.99-mile road course. Justin Allgaier joins Larson on the front row after a lap of 90.562 mph. Sheldon Creed (90.429 mph) qualified third. Aric Almirola (90.375) will start fourth. AJ Allmendinger (90.274) will start fifth.

MORE: Sonoma Xfinity starting lineup

MORE: Alpha Prime Racing’s road woes don’t keep team from competing

Larson is one of seven Cup drivers entered. The others are Almirola (starting fourth), Allmendinger (fifth), Ty Gibbs (seventh), Ross Chastain (15th), Daniel Suarez (17th) and Ty Dillon (32nd).

The green flag is scheduled to wave at 8:20 p.m. ET Saturday on FS1.

Could Daytona International Speedway host NFL games?


The president of Daytona International Speedway says track officials plan to speak with the NFL’s Jacksonville Jaguars about hosting the team’s games if Jacksonville’s stadium is renovated.

The Jaguars will need a temporary home site if plans go forward to renovate the team’s stadium. Daytona International Speedway has been mentioned as a possible candidate. The Jaguars released details Wednesday of what the stadium will look like after the renovation project.

Provided the project is approved by the city of Jacksonville, it is believed the Jaguars would need to find another home site for a couple of seasons while work is being done to its stadium. Daytona International Speedway is among possible sites for the Jaguars to play. More than 100,000 people saw Ricky Stenhouse Jr. win this year’s Daytona 500.

“Daytona International Speedway is a world-renowned sports and entertainment venue and hosts a full schedule of events each year,” said Frank Kelleher, president of Daytona International Speedway, in a statement. “As good neighbors in the Florida sports community, DIS will be speaking with the Jacksonville Jaguars to see if we can assist them with their potential upcoming facility needs around our scheduled events.”

Daytona International Speedway hosted Soccer Fest in July 2022. An announced crowd of 7,573 fans saw the Orlando Pride and Racing Louisville play in a National Women’s Soccer League game at Daytona.