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December 7, 2023

NASCAR Cup Series testing concludes at Phoenix, teams work toward 2024 goals

Kyle Larson and Christopher Bell drive their NASCAR Cup Series cars during a test session at Phoenix.
Alejandro Alvarez

Testing at Phoenix Raceway this week provided a glimpse into what direction short-track racing in the NASCAR Cup Series could look like in 2024.

The two-day, six-team exhibition ran through multiple aerodynamic configurations and Goodyear tire combinations, focusing on the racing on short tracks in the upcoming season. While no immediate determinations were made on-site as to what combinations may end up on the Next Gen vehicles in a couple of months, progress was made to help add clarity to the picture.

“I think our goal is to have some direction coming out of here,” Dr. Eric Jacuzzi, NASCAR’s vice president of vehicle performance, told reporters Tuesday. “I’ve never gone to a test and walked out like, ‘Oh my god, this is great. This is what we’re doing.’ It’s a tough thing to do, right? It’s only six cars and there’s no money and points on the line. But I think for us, it’s coming out of here with direction on the tire, coming out with direction on the aero package that, yes, this is going to be neutral to positive. And then any other things that we’ve learned along the way. And then (Wednesday), we’ll be running mufflers, so making sure (when) we go to LA, we’re not going to have anything unexpected.”

MORE: Cup schedule | Scenes from Phoenix testing

The aerodynamic changes included a new splitter design in addition to a diffuser with two aluminum rakes, all implemented in hopes of reducing the effect of dirty air on vehicles in traffic. Those adjustments were met with positive feedback, notably from defending NASCAR Cup Series champion Ryan Blaney, who returned to the site where he was coronated just one month earlier.

“Yeah, a big difference,” Blaney said Tuesday. “We unloaded exactly how we were here in the fall with this car, ran a couple hours on it and the different splitter, big difference. Massive. Like the way it drives. With that, there’s so much downforce taken off of it. Yeah, the first laps I had, I was like, man, this thing drives way different.

“It should. I mean, it’s a massive aero loss when you do that. And then the simple diffuser wasn’t as big of a change as the splitter, but it was still something to feel. But that front splitter was a huge change, and hopefully we can continue to tweak it a little bit, get it a little better.”

A detailed look at the rear undercarriage of Christopher Bell's No. 20 Toyota during NASCAR Cup Series testing at Phoenix Raceway.
Alejandro Alvarez |

That feedback was notably different from a summer test at Richmond Raceway, where the introduction of a “lift splitter” was met with sentiment that “it wasn’t quite enough” change. Testing at Phoenix left officials more optimistic.

“When we came out of Richmond and were changing aero packages, they felt the same. We could have told them it was the same (package),” Jacuzzi said. “And today, everybody said I definitely noticed the downforce. Like I said, we got some interesting comments to kind of parse through of it was easier to cross the wake or different things. So it seemed like definitely the faster speeds here manifested more of what we expected at Richmond. Again, ultimately, Richmond wasn’t really where we wanted to do that test, but (a rainout at) New Hampshire happened. So it’s definitely a difference. Nobody’s saying, ‘Hey, I didn’t notice your aero package.’ “

Most positive reactions seemed to stem from the different tire combinations Goodyear provided. According to RFK Racing, Chris Buescher went through 24 different sets of tires on the No. 17 Ford over the two-day session. Goodyear aimed to bring tires with thicker treading, similar to what was utilized at Martinsville and which was received well.

“Tire stuff was really good,” Erik Jones of Legacy Motor Club said. “I thought we learned a lot with that in the beginning of the day. I think Goodyear’s got some good notes from that and probably is gonna apply to a lot of places.

“This isn’t really a tire test, but of all the tires I’ve tested over my career, by far probably today was the biggest I’ve noticed a difference.”

NASCAR additionally tested new ductwork to aid cooling using the existing muffler, which have previously been used to lower decibel levels at the Los Angeles Memorial Coliseum and the Chicago Street Course.

“I haven’t felt, really, a heat difference. I could definitely tell a sound difference, which I like,” said Kyle Larson, the 2021 NASCAR Cup Series champion and a winner at Phoenix. “I definitely think our race cars are way too loud — and probably are still too loud with the mufflers. … I think the cars could be quieter to help the fan experience.”

Kyle Larson, Corey LaJoie and Christopher Bell drive their NASCAR Cup Series cars during a test session at Phoenix.
Alejandro Alvarez |

Plans to test gearbox changes intended to address limiting shifting at short tracks were scrapped Wednesday after feedback from a driver debrief signified shifting was less of a concern at Phoenix, therefore resulting in a pivot toward higher focus on aerodynamics and tires instead.

Drivers also pondered after Day 1 how the car would react using the 2023 splitter in addition to the new simplified diffuser, leading to on-track tests Wednesday after officials performed computational fluid dynamics (CFD) testing overnight to eliminate issues with spoiler heights and imbalances.

NASCAR held a similar test session in late January at Phoenix, nearly 11 months ago — six teams set to test different aerodynamic configurations and mufflers. Moving the test to early December provided a longer runway for more meaningful evaluation before jumping into the 2024 season headfirst.

“Especially with The Clash being essentially at the end of January, it wasn’t ideal last year for us to be doing the muffler work,” Jacuzzi said. “We had basically a week, so we weren’t gonna have a ton of time. We did actually respond and do a bunch of cooling stuff before The Clash. This, we figure, would give us more time to process things, and it gives us more time to look at the short-track package next year and what we’re going to do. So it’s really just to get it done early and not waste a month.”

The new year gets underway with the exhibition Busch Light Clash at the Coliseum on Feb. 4 on FOX, MRN Radio and SiriusXM NASCAR Radio.