Dr. Diandra: How NASCAR teams prepare to run a brand-new track

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A race team starts its preparation for the next track by reviewing all the data collected during previous visits. But what if there’s no data to review?

That’s the situation teams faced this week as they visit the repaved and reconfigured Atlanta Motor Speedway.

It’s Always a New Track

For engineers like GM Racing’s Nick Fishbein, the last few years of schedule shakeups and rules modifications have made change a constant in NASCAR.

“I don’t know that preparing for Atlanta is that much different than just preparing for a track, period, especially in the Next Gen environment where everything is new,” Fishbein said.

Even the relationship between manufacturers and teams is changing.

“Not so much because of the Next Gen car,” Fishbein explained, “but a general evolution toward more ingrained support.”

Centralization lets manufacturers reduce duplication of effort and gather more data.

But how do you gather data for a track before it’s even been built?

Jumping the Start

Developing a computer model for a race car running a specific track is an iterative process. You start with what you have and what you can make educated guesses about. From there, every new piece of data helps you refine the model.

Engineers started thinking about Atlanta the moment the ink dried on the blueprints. Fishbein’s group based their model for Atlanta on data from similar tracks, like Daytona and Charlotte. Both tracks hosted early Next Gen testing sessions and actual race data could be added to the model after the Daytona 500.

Experiments on seven-post rigs, engine dynos, and tire-test machines let teams start working on their models even before the track is finished.

Testing Tires Indoors

This is a MTS CT Plus Flat Trac, which Goodyear (and other companies) use for tire testing (Photo courtesy of Smithers.)
This is a MTS CT Plus Flat Trac, which Goodyear uses for tire testing. Goodyear is working on making that virtual, too. (Photo courtesy of Smithers.)

One GM Racing group focuses on tires, using tire-test machines to press a tire against a rotating piece of sandpaper that mimics a track surface. The picture to the right is a FlatTrac tester at Goodyear. GM Racing uses a similar machine at SoVa Motion.  

Although lab data can’t replace race data, it does allow engineers to control variables impossible to control at a track. They can modify everything from force on the tire to its slip angle and camber. If you know a lot about tires in general, it’s not so hard to develop a realistic model for a track that doesn’t yet exist.

Of course, it’s one thing to know the conditions that maximize tire grip. It’s another to get your car set up to provide them.

The On-Track Tire Test

Atlanta’s schedule called for the track to be completed in time for a tire test in late 2021. A pipe burst on the backstretch over Thanksgiving, ruining the subgrade — the all-important foundation for the track. That pushed the tire test back to January 2022.

The months-long delay didn’t worry Greg Stucker, Goodyear’s director of race tire sales.

“We have such a long history with NASCAR and track changes,” he said, “and a good idea of the tire design based on the whole Next Gen package.”

The tread compound, however, needed a physical test. Wear on a tire helps dissipates heat, but a brand-new, smooth track doesn’t offer much wear. Without enough heat dissipation, tires can blister.

“That’s the one area,” Stucker said, “that needs on-track testing.”

The tire test did more than just finalize the tread compound.

“I asked the drivers for feedback,” Steve Swift, senior vice president of operations and development at Speedway Motorsports said. “All three said the dogleg coming off turn four was awkward.”

Drivers were worried that the wall angle relative to the racing path would lead to harder, more head-on collisions rather than glancing blows.

A graphic showing how the turn four dogleg was modified to make it safer.Swift drove it himself. “Even as an engineer, I could tell it was an issue.”

They moved the outside wall in by about 5 feet at the dogleg, which required constructing 320 feet of wall, SAFER barrier and catchfence. Losing 5 feet of racing surface wasn’t an issue because they’d already widened the front stretch from 55 feet to 61-1/2 feet and replaced about three feet of grass with pavement.

Pulling It All Together

Engineers continuously check their computer models against on-track data. Things that work stay in the model, and things that don’t work get modified. With the track and the tire finalized, Goodyear and the manufacturers ran a wheel force test in early March. Specialized sensors measure all the forces on each wheel at every point on the track. These measurements provides the most valuable data because they are of the specific tire that will be run, on the track that will be raced.

Fishbein’s GM Racing group synthesizes data from their internal research groups and their teams. Ultimately, they provide Chevy teams with baseline information and predictions for which variables will matter most at a track. Crew chiefs tailor their car’s setup to their driver’s strengths and preferences.

Fishbein sounded a little disappointed describing their final simulation results for Atlanta. They expect drivers running wide open well into a fuel run, little tire wear, flat lap times and no lifting except to facilitate drafting.

“Any track with a lot of fall off is interesting because you have to weigh priorities between short and long runs, and how to manage tire fall off,” Fishbein said. “I feel like we took an interesting challenge each year and made it simpler.”

The Green Flag

When cars roll onto the starting grid, everything is in the hands of a variable no engineer knows how to model precisely: The driver.

“Nervously excited,” Swift answered when asked how he would feel when the green flag flew for the race. “I’m expecting great racing. We’ve done the work, but how the track drives is different than how the track races.”

Stucker laughed when I asked him the same question. “There’s always a little bit of uncertainty with repaves and reconfigurations, and then you add the new car on top of all that. But we’ve got so much history and data… We’re prepared.”

Fishbein, along with all NASCAR engineers, will watch two races. One is how their drivers finish. The second is how accurately they predicted what would happen at NASCAR’s newest superspeedway — and what they need to improve for next time.