Dr. Diandra: Why aero is so important at intermediate tracks


Kansas Speedway is only the second intermediate track on the 2022 NASCAR Cup Series schedule given that Atlanta runs a superspeedway configuration. These 1.5-mile tracks, which are often unfairly derided as ‘cookie cutter tracks’, highlight the importance of aerodynamic downforce.

Aerodynamics is the science of understanding and predicting the behavior of billions and billions of air molecules moving at high speeds around complicated objects like rockets, airplanes and race cars. I find aerodynamics to be one of the most challenging aspects of motorsports.

Dr. Eric Jacuzzi, who holds a Ph.D. in aerospace engineering from North Carolina State University, is the managing director, aerodynamics/vehicle performance at the NASCAR R&D Center. He agrees that aerodynamics can be a challenge to understand — and to explain.

“In general,” he said, “people try to be too simplistic about aerodynamics. It’s a complex subject, and I think sometimes people try to go with the soundbite.”

He laughed.

“And that usually doesn’t work.”

So let’s go beyond the soundbite to learn a little about aerodynamic downforce and why it’s so important at tracks like Kansas Speedway.

How race cars go fast

A car’s grip depends on the friction between its tires and the track. Grip is proportional to how much force presses the tires into the track. Downforce is literally force in the downward direction.

You experience the importance of downforce anytime you try to drag or slide something. Compare pushing an empty file cabinet to pushing a full file cabinet. The full file cabinet creates more friction — more opposition to motion — because it weighs more. The full file cabinet has more grip.

Grip is bad if you’re moving furniture, but good if you’re racing cars. Grip allows tires to turn without sliding too much and allowing the car to move up the track.

A car’s weight produces mechanical grip. Even the driver adds to the downforce. According to the NASCAR rule book, a Cup car and driver must weigh at least 3,665 pounds. How that 3,665 pounds of mechanical downforce is distributed among the four tires is important, but we won’t worry about that now.

Grip means speed. Teams want as much grip as they can get. A heavier car has more mechanical grip but also requires the engine to make more force to accelerate the additional weight.

So how do you get more grip without making the car heavier?

The answer is (literally) blowing in the wind.

Aerodynamics and Bernoulli’s principle

We usually express Bernoulli’s principle as a long, complicated mathematical equation. But, really, all you need to know is:

The faster air moves, the less pressure it creates.

You can understand a lot of the basics of race car aerodynamics with this one sentence.

For example: Air travels quickly over a car’s hood and roof. Without enough downforce in those areas, the car can experience lift. Lift is great for airplanes, but dangerous to race cars. That’s why roof and hood flaps deploy when the pressure in those areas gets too low.

Splitters utilize the same principle. Air moves more slowly on top of the splitter than underneath it. The force above the splitter is thus greater than the force below the splitter. The net force is down, which pushes the front tires into the track.

The other thing you need to know is that — unlike the weight of the car — aerodynamic forces change depending on how fast the car is going.

Aerodynamic forces depend on speed squared

Drag and downforce are both aerodynamic forces. Downforce pushes down on the car, while drag always acts opposite to the direction the car is moving. Both forces depend quadratically on speed. This means:

  • If you double the speed, the drag and downforce go up by a factor of four.
  • Tripling the speed increases drag and downforce by a factor of nine.

A NASCAR Cup Series car going 180 mph has nine times more downforce than the same car going 60 mph.

The faster you go, the more grip you get. This only works up to point, of course, because you eventually exceed the tires’ capabilities.

Jacuzzi cites a typical value for a non-superspeedway car of around 2,000 pounds of aerodynamic downforce at 200 mph. Superspeedway cars have about 500 additional pounds of aerodynamic downforce at 200 mph.

Below, I’ve plotted the mechanical downforce in black, the aerodynamic downforce in blue and the total downforce in red.

A line chart showing aerodynamic downforce, mechanical downforce and the total downforce on a typical NASCAR Series Cup car

Since the car and driver weigh 3,665 pounds and the aerodynamic downforce at 200 mph is 2,000 lbs, the race car experiences 5,664 pounds of downforce at 200 mph. That’s about the weight of a small elephant.

The car’s tires have to support all that downforce. Most passenger cars, whose primary source of grip is the car’s weight, require tire pressures of 30-35 psi. Goodyear’s recommended tire pressure for the right-side tires at Kansas is 50 psi (front) and 46 psi (rear). The higher tire pressure is necessary because the race cars must support the additional downforce that comes with high speeds.

Aerodynamic downforce makes up about one-third of the total downforce at 200 mph. Anything that decreases the aerodynamic downforce — like getting too close to another car — makes the driver feel as though he’s just hit a patch of ice. At 200 mph.

Below, I graph percentages of mechanical and aerodynamic downforce relative to total downforce as a function of speed. I include this plot to emphasize how much the driver depends on aerodynamic downforce at higher-speed tracks.

A graph showing the percentage of downforce at each speed broken down into mechanical and aerodynamic downforce and

Aerodynamic downforce comprises:

  • 10 percent of total downforce around 90 mph,
  • 25 percent of total downforce at 156 mph,
  • 28 percent of total downforce at 170 mph.

Aerodynamic downforce at Kansas Speedway

The clip below, of Ryan Newman at the 2021 fall Kansas Speedway race shows how his car changes speed as it travels the track.

A video showing part of a lap from Ryan Newman at the 2021 Hollywood Casino 400, showing minimum and maximum speeds

In the three seconds during which his car goes from 183 mph to 169 mph, the aerodynamic downforce goes from 1,674 pounds to 1,428 pounds, a loss of 246 pounds of downforce. That’s like losing a linebacker’s worth of weight in grip.

The driver’s job is to keep the car as close to the limits of traction as possible. Drivers must constantly adjust not only to long-term changes like track conditions and tire wear, but also to the changing grip as the car’s speed changes each lap. The Next Gen car doesn’t provide much sideforce, which means going over the traction limit has a much higher penalty than it used to. That may be why we are close to matching last year’s record for spins.

When I lived in Nebraska, I used to put a couple sacks of sand in my pickup truck’s bed in the winter. That extra rear downforce helped maintain traction when it got icy. You can think of aerodynamic downforce on a race car as a bag of sand — but a bag of sand whose weight changes depending on how fast the car is going.

And which can disappear without warning.

Anytime track speeds exceed above 150 mph, Jacuzzi says, aerodynamics will be important. That’s not to say it’s unimportant at other tracks. But the faster you go, the most important aerodynamics are.

Truck starting lineup at WWT Raceway: Ty Majeski wins pole


Ty Majeski will lead the Craftsman Truck starting lineup to the green flag Saturday at World Wide Technology Raceway after winning the pole Friday night.

Majeski claimed his fourth career series pole and first of the season with a lap of 138.168 mph around the 1.25-mile speedway.

MORE: Truck starting lineup at WWT Raceway

Ben Rhodes, who won last week at Charlotte, qualified second with a lap of 137.771 mph. He was followed by Christian Eckes (137.716 mph), Carson Hocevar (137.057) and Stewart Friesen (137.007).

The series races at 1:30 p.m. ET Saturday on FS1.

Saturday Portland Xfinity race: Start time, TV info, weather


There have been different winners in each of the last nine Xfinity Series races this season. Will the streak continue Saturday at Portland International Raceway?

Those nine different winners have been: Sammy Smith (Phoenix), Austin Hill (Atlanta), AJ Allmendinger (Circuit of the Americas), Chandler Smith (Richmond), John Hunter Nemechek (Martinsville), Jeb Burton (Talladega), Ryan Truex (Dover), Kyle Larson (Darlington) and Justin Allgaier (Charlotte).

Details for Saturday’s Xfinity race at Portland International Raceway

(All times Eastern)

START: The command to start engines will be given at 4:38 p.m. … The green flag is scheduled to wave at 4:46 p.m.

PRERACE: Xfinity garage opens at 10 a.m. … Practice begins at 11:30 a.m. … Qualifying begins at 12 p.m. … Driver introductions begin at 4:15 p.m. … The invocation will be given by Donnie Floyd of Motor Racing Outreach at 4:30 p.m. … The national anthem will be performed at 4:31 p.m.

DISTANCE: The race is 75 laps (147.75 miles) on the 1.97-mile road course.

STAGES: Stage 1 ends at Lap 25. Stage 2 ends at Lap 50.

STARTING LINEUP: Qualifying begins at 12 p.m. Saturday

TV/RADIO: FS1 will broadcast the race at 4:30 p.m. ... Coverage begins at 4 p.m. … Motor Racing Network coverage begins at 4 p.m. and can be heard on mrn.com. … SiriusXN NASCAR Radio will carry the MRN broadcast.

FORECAST: Weather Underground — Sunny with a high of 73 degrees and a zero percent chance of rain at the start of the race.

LAST TIME: AJ Allmendinger won last year’s inaugural Xfinity race at Portland by 2.8 seconds. Myatt Snider finished second. Austin Hill placed third.

NASCAR Friday schedule at WWT Raceway, Portland


Craftsman Truck Series teams will be on track Friday at World Wide Technology Raceway to prepare for Saturday’s race. Cup teams will go through inspection before getting on track Saturday.

Xfinity Series teams will go through inspection Friday in preparation for their race Saturday at Portland International Raceway.

Here is Friday’s schedule:

World Wide Technology Raceway at Gateway (Cup and Trucks)


Friday: Partly cloudy with a high in the low 90s.

Friday, June 2

(All times Eastern)

Garage open

  • 1 – 8 p.m. Craftsman Truck Series
  • 4 – 9 p.m. Cup Series

Track activity

  • 6 – 6:30 p.m. — Truck practice (FS1)
  • 6:30 – 7:30 p.m. — Truck qualifying (FS1)

Portland International Raceway (Xfinity Series)

Weekend weather

Friday: Mostly sunny with a high of 77 degrees.

Friday, June 2

(All times Eastern)

Garage open

  • 6-11 p.m. Xfinity Series (no track activity on Friday)

Friday 5: NASCAR’s $1 million question is can the culture change?


NASCAR Cup teams have paid nearly $1 million in fines this season, more than triple what they paid last season for inspection-related infractions.

The money — $975,000 after just 14 of 36 points races — goes to the NASCAR Foundation. While the fines help a good cause, it is a troubling number, a point that a senior NASCAR official made clear this week.

Stewart-Haas Racing was the latest Cup team to be penalized. NASCAR issued a $250,000 fine, among other penalties, for a counterfeit part found on Chase Briscoe’s car following Monday’s Coca-Cola 600. The team cited a “quality control lapse” for a part that “never should’ve been on a car going to the racetrack.”

Elton Sawyer, NASCAR senior vice president of competition, said this week that if violations continue, the sanctioning body will respond. NASCAR discovered the infraction with Briscoe’s car at the R&D Center. Series officials also discovered a violation with Austin Dillon’s car at the R&D Center after the Martinsville race in April.

“If we need to bring more cars (to the R&D Center), we’ll do that,” he said. “Our part of this as the sanctioning body is to keep a level playing field for all the competitors, and that’s what they expect us to do and that’s what we’ll continue to do. … Whatever we need to do, we will do that.”

Sawyer also noted that the “culture” of race teams needs to change with the Next Gen car.

“From a business model and to be equitable and sustainable going forward, this was the car that we needed,” Sawyer said. “To go with that, we needed a deterrent model that would support that.

“We’ve been very clear. We’ve been very consistent with this … and we will continue to do that. The culture that was in our garage and in the race team shops on the Gen-6 car was more of a manufacturing facility. The Next Gen car, that’s not the business model.

“The race teams, they’re doing a better job. We still have a lot of work to do, but they have to change that culture within the walls of the race shop.”

While NASCAR has made it clear that single-source vendor parts are not to be modified, teams will look for ways to find an advantage. With the competition tight — there have been 22 different winners in the first 50 races of the Next Gen car era — any advantage could be significant.

Twelve races remain, including Sunday’s race at World Wide Technology Raceway, before the playoffs begin. The pressure is building on teams.

“Some race teams, at this stage in the game, their performance is not where they would like for it to be and they’re going to be working hard,” Sawyer said. “If they feel like they need to step out of bounds and do things and just take the risk, then they may do that. That’s not uncommon. We’ve seen that over the years.

“The one thing that we have to keep in mind is we’ve raced the Next Gen car for a full season. We’re in year two, just say 18 months into it. So last year, they were just getting the parts and pieces, getting ready, getting cars prepared and getting to the racetrack.

“Now they’ve had them for a year. They’ve had them for an offseason. It’s given their engineers and the people back in the shop a lot more time to think, ‘Maybe we could do this, maybe we could do that.’

“By bringing these cars back (to the R&D Center) and taking them down to basically the nuts and bolts and a thorough inspection — and we will continue to do that — I believe we will get our message across. We’ll have to continue to do this for some period in time, but I have great faith that we will get there.”

A similar message was delivered by Sawyer to drivers this week when NASCAR suspended Chase Elliott one race for wrecking Denny Hamlin in retaliation for being forced into the wall.

Sawyer told SiriusXM NASCAR Radio that “in the heat of the battle things happen, but (drivers) have to learn to react in a different way.”

Sawyer also noted that the message on how to race wasn’t just for those in Cup.

“We have to get that across not only to our veterans, guys that are superstars like Denny, like Bubba (Wallace) and like Chase and all our of national series Cup drivers, but also our young drivers that are coming up through the ranks that are racing in the Northeast in modifieds and in short tracks across the country,” he said. “That’s just not an acceptable behavior in how you would race your other competitors.

“There are a lot of things you can do to show your displeasure. That’s just not going to be one of them that we’re going to tolerate.”

2. Special ride 

Corey LaJoie gets to drive a Hendrick Motorsports car this weekend due to Chase Elliott’s one-race suspension.

“It’s a far cry difference from when I started my Cup career six years ago,” LaJoie said on his “Stacking Pennies” podcast this week. “There was a Twitter page “Did Corey crash?” … Going from that guy just trying to swim and stay above water and trying to learn the ropes to filling in for a champion like Chase Elliott for Hendrick Motorsports, it feels surreal.”

It was a little more than three years ago that LaJoie gave car owner Rick Hendrick a handwritten note to be considered to replace Jimmie Johnson in the No. 48 car after the 2020 season.

“This was the first time I’ve gotten a letter from the heart,” Hendrick told NBC Sports in February 2020 of LaJoie’s letter. “I’ve gotten letters and phones calls, usually from agents. It was really a heartfelt letter and it was really personal.

“I was impressed with him before and am more impressed after.”

LaJoie admitted on his podcast this week that he wouldn’t have been ready to drive the No. 48 car then.

“I wouldn’t have been ready, whether it be in my maturation, my game, my knowledge of the race cars,” he said. “The person that I was wasn’t ready for the opportunity like that.”

Now he gets the chance. He enters this weekend 19th in the season standings, 38 points behind Alex Bowman for what would be the final playoff spot at this time.

“It’s an opportunity to hopefully show myself, as well as other people, what I’ve been thinking (of) my potential as a race car driver,” LaJoie said on his podcast. “But I also think you have to just settle in and be appreciative of the opportunity.”

3. Special phone call

With Corey LaJoie moving into Chase Elliott’s car for Sunday’s Cup race, LaJoie’s car needed a driver. Craftsman Truck Series driver Carson Hocevar will make his Cup debut in LaJoie’s No. 7 car for Spire Motorsports.

Once details were finalized this week, the 20-year-old Hocevar called his dad.

“I don’t know if he really believed it,” Hocevar said.

He told his dad: “Hey, this is actually happening.”

His father owns a coin and jewelry shop and is looking to close the store Sunday and have someone watch his two puppies so he can attend the race.

For Hocevar, it’s quite a turnaround for a driver who has been at the center of controversy at times.

Ryan Preece was critical of Hocevar’s racing late in the Charlotte Truck event in May 2022. Preece said to FS1: “All you kids watching right now wanting to get to this level, don’t do that. Race with respect. Don’t wreck the guy on the outside of you trying to win your first race. It doesn’t get you anywhere.”

NASCAR penalized Hocevar two laps for hooking Taylor Gray in the right rear during the Truck race at Martinsville in April.

Hocevar acknowledged he has had to change how he drives.

“Last year was really, really tough for me and that’s no excuse,” Hocevar said this week. “I just was mentally wrong on a lot of things, had the wrong mindset. I wanted to win so badly that I thought I could outwork stuff and it kind of turned some people away. … I wasn’t enjoying the time there. I was letting the results dictate that.

“I was taking results too personal. If we were going to be running seventh, I took it as I was a seventh-place driver and I wasn’t good enough. So I started making desperate moves. I did desperate things at times, even last year, that I’ve been able to calm down and look myself in the mirror and had a lot of heart-to-heart conversations.”

He called the Martinsville race “a turning point” for him and knew he needed to change how he drove. He enters this weekend’s Truck race with three consecutive top-five finishes.

4. Moving forward

In a way, Zane Smith can relate to what Carson Hocevar will experience this weekend. Smith, competing in the Truck Series, made his Cup debut last year at World Wide Technology Raceway. Smith filled in for RFK Racing’s Chris Buescher, who missed the race because of COVID-19 symptoms. Smith finished 17th.

“That one that I got for RFK Racing was a huge opportunity,” Smith said of helping him get some Cup rides this season. “I was super thankful for that. I think that run we had got my stock up and then, honestly, getting the Truck championship helped that rise as well.

“I think just time in the Cup car is so important, and I think once that new Cup car came out, people realized that you don’t have to do the route of Truck, Xfinity, Cup. The Cup car is so far apart from anything, though it does kind of race like a truck, so I don’t think you need to go that round of Truck, Xfinity, Cup. I think a lot of people would agree with me on that.

“I’m happy for these Cup starts that I’m getting. I’m happy for that one that I got last year at a place like Gateway. I think every time that you’re in one you learn a lot.”

Smith has made five Cup starts this season, finishing a career-best 10th in last week’s Coca-Cola 600 for Front Row Motorsports. The former Truck champion has two Truck series wins this year and is third in the season standings.

5. Notable numbers

A look at some of notable numbers heading into this weekend’s Cup race at World Wide Technology Raceway in Madison, Illinois:

5 — Most points wins in the Next Gen car (William Byron, Kyle Larson, Joey Logano, Chase Elliott)

7 — Different winners in the last seven points races: Christopher Bell (Bristol Dirt), Kyle Larson (Martinsville), Kyle Busch (Talladega), Martin Truex Jr. (Dover), Denny Hamlin (Kansas), William Byron (Darlington), Ryan Blaney (Coca-Cola 600).

17 — Points between first (Ross Chastain) and sixth (Christopher Bell) in the Cup standings

88 — Degrees at Kansas, the hottest temperature for a Cup race this season (the forecast for Sunday’s race calls for a high in the low 90s)

100 — Consecutive start for Austin Dillon this weekend

500 — Cup start for Brad Keselowski this weekend

687 — Laps led by William Byron, most by any Cup driver this season

805 — Cup start for Kevin Harvick this weekend, tying him with Jeff Gordon for ninth on the all-time list.