Dr. Diandra: Firesuits for race cars

NASCAR Cup cars fire
Photo: NBC Sports

Endurance racer Stephen Cox relates a bone-chilling first-person account (in two parts) of his car catching fire at 125 mph. He was amazed at how the smoke made it almost impossible for him to see his belts or the window net release.

Fire is not unique to any one racing series. When Ryan Blaney’s car caught on fire in the 2018 Coca Cola 600, his crew chief asked if he had activated the fire suppression system.

“Dude, I was trying to get out of it. I didn’t look for the pin. I couldn’t see it regardless,” Blaney told him.

The Next Gen car has had more than its share of fires in its inaugural season. Tyler Reddick experienced the first Next Gen fire at a March test at Kansas. During the season, fire has impacted Chris Buescher, Joey Logano, Cole Custer, Chase Briscoe, J.J. Yeley and Kevin Harvick — all Ford drivers — and Alex Bowman.

After the Indianapolis race, NASCAR mandated an insulating shroud around the right-side exhaust pipes. Officials theorized that contact moved the pipes, allowing them to set fire to the foam inside the door panel.

But fires persisted.

So did driver frustration.

After a fire knocked championship contender Harvick out of the Darlington playoff race, NASCAR issued more technical changes. These modifications are based on a new theory: that small pieces of rubber inside a car start fires.

What causes fire?

Knowing how fire starts is the key to stopping it.

Fire is a chemical reaction between fuel and oxygen in the presence of heat. Engines use spark plugs to combust gasoline. Your body oxidizes glucose and fats in a similar reaction to keep your metabolism going.

Sustaining a fire requires all three components — fuel, oxygen and heat — in quantities sufficient to sustain the chain reaction that keeps the blaze going. Fires stop when one or more of the three components is reduced or eliminated.

Air is about 21% oxygen. Rolling someone on fire on the ground or in a blanket separates the fire from oxygen. That’s the same reason putting out a grease fire by clapping a lid on the pan works. No oxygen, no fire.

Water cools, thus eliminating the heat component. But water won’t extinguish a gasoline fire for the same reason it doesn’t work on grease fires. Liquids like gasoline, paint thinner, etc. don’t mix with water.

NASCAR uses chemical fire suppressants in the car and in the containers safety personnel carry. These chemicals gobble oxygen. A thermally activated extinguisher is required in the fuel cell area, but the suppression system in the driver’s compartment is manually operated.

How firesuits work

The zeroth rule of motorsports safety is: Hope for the best and plan for the worst. That means not just trying to avoid fires, but protecting people if a fire does start.

No material is fireproof. Drivers’ firesuits protect them by providing thermal insulation, being lousy fuel sources and blocking oxygen.

Quilting traps air between a firesuit’s layers. Air is a great thermal insulator, which decreases the amount of heat that can penetrate the firesuit.

Most firesuits are made from Nomex or Nomex blends, although there are increasingly more material options. Nomex may not have the super strength of its sibling molecule Kevlar, but Nomex doesn’t burn: It chars. Charring forms a layer of carbon around the fiber, as shown in the drawings and photos below.

A drawing with photos showing how Nomex creates a char layer around the fiber instead of burning

Carbon is a superb thermal insulator that provides additional protection from the heat. Because the char is not flammable, it doesn’t provide fuel for the fire.

Finally, the expanding Nomex fibers close the holes in the weave of the fabric, as I’ve drawn below. That prevents oxygen and flame from getting to the driver’s skin.

A drawing showing how the expanding Nomex fibers close the holes in a firesuit's weave to prevent oxygen from getting through

All driver gear must be fire-resistant, from headsocks to shoes and underwear. Even patches must conform to standards established by the SFI Foundation. That gear gives the driver about 10 additional seconds before he or she will suffer second-degree burns.

If you want to learn more about firesuits, check out this video I made with the National Science Foundation.

A firesuit for the car

Any material will combust or melt given enough heat and oxygen. Carbon fiber is stable to very high temperatures, but the resins and glues holding carbon-fiber composite together are flammable at lower temperatures.

NBC Sports analyst Steve Letarte broke down the most-recent NASCAR-mandated changes in the video below. The first fix seals places where bits of rubber can get into the car. The second fix replaces part of the polymer right-side door panel — the area closest to the exhaust pipes — with stainless steel.

A video from NBC Sport's Steve Letarte explaining the fixes NASCAR mandated to stop car fires

The only thing I’ll add to the video is that smaller pieces of fuel catch fire more easily. You can put a propane torch to a tire and it won’t burn. But marbles — small pieces of rubber and track grit — have a lot of surface area. That means a lot of places to initiate combustion. That may also be why the problem didn’t make itself known until actual races at tracks that collect a lot of rubber.

NASCAR suggested one more optional fix: intumescent paint. This paint is both a great piece of materials science and fun to say.

Intumescent (in-too-MESS-scent) means expanding, often in the presence of heat. Research on intumescent paint took off after 9/11 and the surprising way the steel in the World Trade Center melted. Intumescent paints are now required in many commercial buildings. They’re also common in drag racing.

Intumescent paint works much like Nomex. Heat swells the paint, but to a much greater degree. The video below shows an example of an intumescent paint used in construction.

A video showing intumescent paint expanding

Also like Nomex, the char cannot become fuel. The example below uses a regular piece of cardboard with and without protective paint.

A video showing how intumescent paint prevents cardboard from burning

NASCAR limits painted areas to where the exhaust passes close to the body panels and the right-side foam. Teams also have the option of painting the door foam.

There’s a small weight penalty, but it’s nowhere as big as the consequences of being knocked out of a playoff race because of a fire.

NASCAR weekend schedule for Talladega Superspeedway


The NASCAR Cup Series playoffs roll into Talladega Superspeedway, a center of uncertainty, for the second race in the Round of 12 this weekend.

Sunday’s race (2 p.m. ET, NBC) could place the first driver in the Round of 8. Any playoff driver who wins the race automatically advances to the next round.

Through the playoffs to date, playoff drivers are batting zero in the race-win category. Non-playoff drivers — Tyler Reddick, Chris Buescher, Bubba Wallace and Erik Jones — have scored wins in the first four playoff races.

Joey Logano leads the playoff points entering the race. Ross Chastain, who won at Talladega earlier this year, is second.

The four drivers below the cutline are Austin Cindric, William Byron, Christopher Bell and Alex Bowman. Byron was above the line earlier this week but was penalized 25 points for spinning Denny Hamlin under caution last Sunday at Texas Motor Speedway. That move lifted Chase Briscoe above the cutline.

Playoff races also are scheduled for the Xfinity Series (Saturday, 4 p.m. ET, USA Network) and the Camping World Truck Series (Saturday, 12:30 p.m., FS1) at Talladega.

Here’s a look at the Talladega weekend schedule:

Talladega Superspeedway (Cup, Xfinity and Truck)

Weekend weather

Friday: Sunny. High of 78.

Saturday: Partly cloudy. High of 74.

Sunday: Intervals of clouds and sun. High of 75.

Friday, Sept. 30

(All times Eastern)

Garage open

  • 9 a.m. – 6 p.m. — Truck Series
  • 10:30 a.m. – 7:30 p.m. — Xfinity Series
  • 2 – 7 p.m. — Cup Series

Track activity

  • 3:30 – 5 p.m. — Truck Series qualifying
  • 5:30 – 7 p.m. — Xfinity Series qualifying (USA Network)

Saturday, Oct. 1

Garage open

  • 8:30 a.m. – 12:30 p.m. — Cup Series
  • 9:30 a.m. — Truck Series
  • 1 p.m. — Xfinity Series

Track activity

  • 10:30 a.m. – Noon — Cup Series qualifying (NBC Sports app, Motor Racing Network, Sirius XM NASCAR Radio)
  • 12:30 p.m. — Truck Series race (94 laps, 250 miles; FS1, Motor Racing Network, SiriusXM NASCAR Radio)
  • 4 p.m. — Xfinity Series race (113 laps, 300 miles; USA Network, Motor Racing Network, SiriusXM NASCAR Radio)

Sunday, Oct. 2

Garage open

  • 11 a.m. — Cup Series

Track activity

  • 2 p.m. — Cup Series race (188 laps, 500 miles; NBC, Motor Racing Network, SiriusXM NASCAR Radio)

Short-track ace Sam Ard shares Xfinity record with Noah Gragson


Former two-time Xfinity Series champion Sam Ard’s name returned to the forefront in the past week as Noah Gragson tied Ard’s series record for consecutive victories at four.

Although Ard has been nominated for the NASCAR Hall of Fame, his exploits generally aren’t well-known among many who follow the modern sport of stock car racing. He was on the Hall voting list for the 2023 class but was not elected.

In the 1970s and ’80s, Ard was a short-track master in the vein of stars like Jack Ingram, Harry Gant and Butch Lindley, drivers who could show up at virtually any half-mile track across the country and take home the trophy.

He won the NASCAR Late Model (now the Xfinity Series) championship in 1983 and 1984, scoring 18 wins across those two seasons. He put together four victories in a row late in the 1983 season, winning at South Boston, Virginia; Martinsville, Virginia; Rougemont, North Carolina and Charlotte.

Ard was so dominant in 1984 that he had wrapped up the seasonal championship with two races remaining. In 28 series starts that year, he had 24 top-five finishes and 26 top-10 runs. He won eight times.

In the next-to-last race of the 1984 season, at North Carolina Speedway in Rockingham, Ard suffered critical head injuries when his car slid in fluid from another vehicle and hit the track’s outside wall.

That crash effectively ended Ard’s career and impacted the rest of his life. Ard often talked of learning to walk again as part of his recovery. He said he would use a walker in a pile of sawdust in his backyard so that the landing would be softer when he fell.

Ard eventually was diagnosed with Alzheimer’s disease and Parkinson’s disease. In 2006, responding to Ard’s financial problems, drivers Kyle Busch, Kevin Harvick and Dale Earnhardt Jr., among others, launched a drive to raise funds for his family.

Ard, a native of Scranton, S.C., died in April 2017. He was 78.






Drivers to watch in Cup Series race at Talladega Superspeedway


The NASCAR Cup Series playoffs will reach a critical point Sunday in a 500-mile chase at treacherous Talladega Superspeedway.

The overriding factor in any race at Talladega, NASCAR’s biggest track, is the unknown. With cars running so fast and so close together, multi-car accidents are not only possible but expected, and it’s easy to become the innocent victim of someone else’s mistake.

MORE: NASCAR penalizes William Byron for spinning Denny Hamlin

The tension is doubled for the 12 playoff drivers. A bad finish at Talladega could open the door for a probable playoff exit at the end of the round Oct. 9 at the Charlotte Motor Speedway Roval.

The playoffs to date have seen four wins by non-playoff drivers, an unprecedented result. Tyler Reddick was the most recent to join that list with a win last Sunday at Texas Motor Speedway.

A look at drivers to watch at Talladega:


Denny Hamlin

  • Points position: 6th
  • Last three races: 10th at Texas, 9th at Bristol, 2nd at Kansas
  • Past at Talladega: 2 career wins

Although he hasn’t won, Hamlin has finished in the top 10 in all four playoff races. In the past six races at Talladega, he has four finishes of seventh or better. Now if he can just keep people from running into him…

William Byron

  • Points position: 3rd
  • Last three races: 7th at Texas, 3rd at Bristol, 6th at Kansas
  • Past at Talladega: Best career finish is a second

Byron stands alone as the only playoff driver who has been able to avoid major crashes and trouble in the pits, and he has finished in the top 10 in all four playoff races. After Tuesday’s penalty for his incident with Denny Hamlin at Texas, he sits below the cutline entering Sunday’s race.

Brad Keselowski

  • Points position: 24th
  • Last three races: 8th at Texas, 13th at Bristol, 25th at Kansas
  • Past at Talladega: 6 wins, the active leader

Even in trying times, Keselowski is a threat at Talladega, where he last won in April 2021 (his last Cup victory). He has led 268 laps there in the past 13 races.


Kyle Busch

  • Points position: 15th
  • Last three races: 36th at Texas, 34th at Bristol, 26th at Kansas
  • Past at Talladega: 1 career win, in 2008

Is Busch going to steadily disappear into the mist as he rides out the final weeks of his final year with Joe Gibbs Racing? His best finish in the past four races is 26th. On the positive side this week, he’s the only driver to finish in the top 10 in this year’s three races at Daytona and Talladega.

Chase Elliott

  • Points position: 8th
  • Last three races: 32nd at Texas, 2nd at Bristol, 11th at Kansas
  • Past at Talladega: 1 career win, in 2019

Can Elliott rebound from a fiery finish and a 32nd-place run at Texas? Playoff points give him some comfort, but a second career win at Talladega would be greatly appreciated in the Hendrick camp.

Martin Truex Jr.

  • Points position: 17th
  • Last three races: 31st at Texas, 36th at Bristol, 5th at Kansas
  • Past at Talladega: Best career finish is 5th

Will one of the sport’s most enduring mysteries continue at Talladega? In 70 career starts at Daytona and Talladega, Truex, a former champion and a smooth driver, has zero wins. At Talladega, he has only three top-five finishes in 35 starts.




NBC will broadcast final six NASCAR Cup Series playoff races


The final six races in the chase for the NASCAR Cup Series championship will be televised by NBC.

The races remaining on the schedule are at Talladega Superspeedway (Oct. 2), the Charlotte Motor Speedway Roval (Oct. 9), Las Vegas Motor Speedway (Oct. 16), Homestead-Miami Speedway (Oct. 23), Martinsville Speedway (Oct. 30) and Phoenix Raceway (Nov. 6).

NBC’s broadcasting team will be on hand Sunday for what is typically a seasonal highlight — a 500-mile race at Talladega Superspeedway. The next week the playoffs move on to Charlotte for a cutoff race. The lowest four drivers in the playoff point standings will be eliminated from championship competition.

The Round of 8 is scheduled at Las Vegas, Homestead and Martinsville, with the tiny Martinsville track serving as the final cutoff race. The four drivers who advance from Martinsville will race for the title at Phoenix Nov. 6.

The high drama of the Phoenix race, in which the championship will go to the highest finisher of the four competing drivers, will be carried by both NBC and Peacock.

Post-race commentary and analysis for all six remaining Cup races will be carried on Peacock.

Kyle Larson is the series defending champion. Joey Logano carries the point lead into Sunday’s race at Talladega.