NASCAR Cup Series

Everything you need to know about the dirt race at Bristol Motor Speedway

Updated Jul. 20, 2021 8:19 p.m. ET

By Bob Pockrass
FOX Sports NASCAR Writer

Bristol Motor Speedway, situated in the Appalachian Mountains, likes to call itself the Last Great Coliseum.

From Friday through Sunday, it will be the "Last Great Experiment."

This coliseum has gone through a change for the 2021 spring race. The concrete track is still there. But on top of it is a layer of sawdust and 23,000 cubic yards of dirt.

"What’s great about dirt racing, as the track goes through transitions, it’s always going to change," said Austin Dillon, who won the truck race on the Eldora Speedway dirt in 2013. "There might be a point in the race where, ultimately, you have to be on the bottom, and you’ll be fighting for it.

"It’ll go through so many transitions throughout the race, and that’s what’s cool about dirt racing. You have to be comfortable with change because it changes throughout the race, and to be good at it, you have to search constantly."

The NASCAR Cup Series will conduct its first race on dirt since 1970 when the event goes green on Sunday. For fans who don’t watch dirt all that often — or maybe caught just a few highlights when the trucks competed on the Eldora Speedway dirt from 2013 to 2019, here are some things we thought you should know.

1. Dirt is different

The Bristol track is "red dirt," which is native to the area and considered generally good for racing. The track includes a bottom layer of soil that was used the last time Bristol had dirt events in 2000 and 2001. The second layer came from a campground near the track, and the third layer came from Bluff City about 20-30 miles away. Bristol tested about 15 types of dirt from the area to try to find the best dirt – the kind that has low silt and sand content so that it packs well but also retains some water. It took 2,300 truckloads of dirt to create the surface.

"Dirt tracks start out wet and muddy, which doesn’t have a lot of grip, and then they go to tacky, which has a lot of grip," said Stewart Friesen, a truck series driver who has significant dirt racing experience. "And then they do get black and slick — and blue groove that can be abrasive and lay rubber, or it can be slick."

2. Banking matters

The Bristol concrete track without the dirt is banked 30 degrees, with a racing surface about 40 feet wide. For this dirt race, the dirt is banked 19 degrees, with a racing surface about 50 feet wide. In initially putting the dirt on the track, GPS was used to try to make sure the configuration was the way the track and NASCAR wanted.

3. The challenges of the dirt track

Dirt track preparation is a constant challenge, and the track needs to be prepared between events. The dirt is sometimes tilled and then packed down using heavy "packer" cars that run around the track. A water truck will be used to give it the moisture needed, including possibly during cautions and stage breaks. The key is to use a water truck to put enough moisture in the track so that it doesn’t get dusty throughout the race but not so much that it is muddy and difficult for the racers. There also is often the development of the "cushion" – a buildup of dirt either by the wall or at the apron — and if a driver can work it just right, the driver can gain speed in those areas. But hit the cushion wrong, and it can cause a sprint car to flip or a stock car to lose pace.

"It’s not a dirt that I believe you’re going to see a cushion built. It doesn’t do that," Dillon said. "This stuff kind of creates a fluff, and it gets up there. You can gain grip because it might be wet up there for a while, but it’s not something that you can use as a curb to catch you, which is different."

4. How will the cars race?

Cup cars won’t race like dirt late models, the type of cars somewhat similar to Cup cars that regularly compete on dirt. Those who have watched dirt races have seen dirt late models make huge gains by sliding in the corners. The Cup cars won’t be able to do that nearly as effectively because NASCAR won’t allow the suspension in the vehicles to perform that maneuver – it would not be cost-effective for teams to develop and replace all the suspensions for one race.

"These things are just so heavy, and the tire is not at all indictive to producing grip," two-time Cup champion Kyle Busch said. "It seems like it’s a full-fledged ice rink. Like literally, you are just out there on ice, trying to make your way around the track.

"That’s why I’ve never given much participation to it [at Eldora], but obviously now, I have no choice. ... It’s just going to be a learning experience, for sure. These vehicles are nothing like I’ve driven on dirt, probably, so it’s going to be interesting."

5. Speed and distance

The cars won’t run at the speed they typically do at Bristol. The Cup race Sunday is 250 laps, half the usual distance, and that is an unusually long race on a dirt track. NASCAR hopes it takes three hours. We’ll see if they can complete the race without a bunch of cautions and without needing to work on the track during the event.

"I think with Bristol having more banking, you’ll kind of have more grip than we had at Eldora," said Kyle Larson, who won one of the truck races at Eldora. "So we’ll have the confidence probably in our cars to be able to move around. I actually think it’ll be a better race because of it.

"I watched the street stocks and stuff this past weekend, and they were able to run, like, three- or four-wide at times, and it was fun racing."

6. Analyzing the cars

The Cup cars will be very similar to the cars Cup drivers race on other short tracks, especially in appearance. But among the differences fans will see is that there will be no front splitter overhang. A debris deflector can be placed on the hood, with the deflector a maximum 18 inches long and 6 inches high. (Unlike many dirt late models, the Cup cars will keep their windshields.)

The rear spoiler will be different, as it will be 6 inches high and 51 inches long. Normally, it is 8x61 for intermediate tracks, 9x61 for superspeedways and 2.75x61 for short tracks/road courses. Among other tweaks, screens/coverings will be allowed in front of various ducts to keep dirt out. Body side stiffeners will be allowed, and deck-lid hinges, spindle and steering arm assembly can be reinforced because of the expected punishment those pieces will take. Brake caliper mounting can be modified.

7. The faves

Who will be good? Larson, Dillon, Bubba Wallace, Christopher Bell, Chase Briscoe and Stewart Friesen (Friesen will make his Cup debut in the Spire Motorsports No. 77 car) all won truck races on dirt at Eldora Speedway. Some will point to the sprint-car experience on dirt of Bell, Briscoe and Larson, but a stock car on dirt is so different that many of the skills don’t translate. What does translate is adjusting for the conditions of the track, which can change throughout the race as well as from day to day.

"Obviously, a Cup car is 2,000 more pounds than the race cars I’m used to running and have 200 less horsepower," Larson said. "Yes, Bell and I have a lot of dirt experience, but I don’t really believe it to be that beneficial to us in a stock car because it’s so different."

8. The preparation

Several drivers – including Dillon, Kyle Busch, Joey Logano, Chris Buescher, Corey LaJoie, Cole Custer and Chase Elliott – raced last week at the track in modifieds or dirt late models. Seven Cup drivers – Ryan Newman, Daniel Suarez, Briscoe, Wallace, Larson, Kevin Harvick and Martin Truex Jr. – will compete in the truck event this weekend to get more track time.

"I would have loved to have gotten in a truck," Elliott said last week. "It didn’t work out, but I think going and doing this will help me just be able to visualize things, understand the race track a little more and just kind of get a little bit of a feel for what dirt is like there at Bristol before we just show up."

9. Don't wear white!

Fans will get dirty. If you are going to the race, don’t wear white. That’s for sure. There will be plenty of dust filling the air, and it is not rare for little chunks of dirt to fly into the areas near the fence. Bristol is teaching its concessionaires how to package food and beverages with lids and enough covering to help fans keep their food (somewhat) clean.

10. Lining 'em up

NASCAR will use 15-lap heat races to determine the lineup. Drivers will get points based on heat race finish on a 10-to-1 scale, with a bonus point for every spot improved from where they started to where they finished. Drivers who lose spots will not be docked points. The starting lineup will go from the most points to the fewest points, with ties broken by where teams are in the owner standings.

11. What's up with pit row?

NASCAR didn’t want to have drivers trying to gain spots while coming down pit road, which remains concrete, so there will be controlled pit stops. Teams can only change tires and fuel on the stage breaks (no stage is longer than a fuel run), and teams won’t lose or gain spots based on time spent on pit road. Those who don’t pit during the stage breaks will start ahead of those who do.

12. How will the tires hold up?

Speaking of tires, these dirt tires are treaded and designed to give traction. They are bias-ply tires – not the typical NASCAR radials, which means there is no belt package under the tread, which allows for it to conform to a typical uneven dirt track surface. The tread has blocks designed to bite into the dirt, and the grooves in the tread help evacuate the dirt.

The right-side tire is similar to what teams typically run, and the left-side tire is significantly shorter to build in more stagger. The right-side tire is a 15-inch tire; the left-side tire is an 11-inch tire.

13. Mud

If it rains and track conditions make it so the drivers don’t have any traction (either so slick or so muddy), or the track is in a condition where mud would be slung into the ducts and cause the cars to overheat, the race will have to be stopped. It likely would take a couple of hours to get the track ready to race, but it would depend on the amount of rain. The track is sealed in a way by those packing cars, so the hope is that rain runs off the banking without creating a mud pit. So far, the biggest concern would be a freeze and thaw because that would bust off the top of the track, requiring more tilling and work.

14. The future of the dirt

The track hopes the layer of sawdust at the bottom will make it easier to remove the dirt, which won’t happen until a month after the Cup event because there will be two weekends of World of Outlaws sprint cars and late models racing there.

"They haven't put dirt on Bristol since the early 2000s, when the sprint cars ran there, and we'll be about at least 10 seconds slower than the sprint cars," Ryan Blaney said. "That’ll be a challenge for everybody. And it'll be interesting to see how the track changes throughout the race.

"Does it get really slick or rubber down or what? I don't really know what to expect, but you go in prepared the best you can for it and see."

Thinking out loud

The choice of Bristol for this event has created a lot of debate. Many dirt track fans would rather see this at an Eldora or a Knoxville, two of the more iconic dirt tracks. But attendance for this race, considering it’s at Bristol, will be well above what either of those venues can hold.

Bristol also is a familiar place, at least, to teams and broadcasters.

The criticisms – that these drivers don’t have much experience on dirt, so it’s not all that fair for it to be a points race – are valid. It’s best to think of this race as a first step, a one-time deal for Bristol and a test to see if dirt will work with Cup cars. If this goes well, those other venues will be there. Bristol isn’t going to want to do this every year – getting the dirt out of every seat and air-conditioning unit in the area is going to be a big task.

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They said it

"It always feels good to win anything." – William Byron after his eNASCAR iRacing Pro Invitational Series win

Bob Pockrass has spent decades covering motorsports, including the past 30 Daytona 500s. He joined FOX Sports in 2019 following stints at ESPN, Sporting News, NASCAR Scene magazine and The (Daytona Beach) News-Journal. Follow him on Twitter and Instagram @bobpockrass. Looking for more NASCAR content? Sign up for the FOX Sports NASCAR Newsletter with Bob Pockrass!