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 will not race at Auto Club Speedway in 2024


LOS ANGELES — Auto Club Speedway will not host a NASCAR race next year because of plans to convert the 2-mile speedway into a short track.

It will mark only the second time the Cup Series has not raced at the Southern California track since first competing there in 1997. Cup did not race at the track in 2021 because of the pandemic.

Dave Allen, Auto Club Speedway president, also said Saturday that “it’s possible” that the track might not host a NASCAR race in 2025 because of how long it could take to make the conversion. 

MORE: Details for Sunday’s Clash at the Coliseum 

NASCAR came to the Fontana, California, track during the sport’s expansion in the late 1990s that also saw Cup debut at Texas (1997), Las Vegas (1998) and Homestead (1999).

Auto Club Speedway begins the West Coast swing this season, hosting the Cup Series on Feb. 26, a week after the Daytona 500. The series then goes to Las Vegas and Phoenix the following two weeks.

Auto Club Speedway has been among a favorite of drivers because of its aging pavement that put more of the car’s control in the hands of competitors. 

Allen said that officials continue to work on the track’s design. It is expected to be a half-mile track. With NASCAR already having a half-mile high-banked track (Bristol) and half-mile low-banked track (Martinsville), Allen said that a goal is to make Auto Club Speedway stand out.

“It has to make a statement, and making sure that we have a racetrack that is unique to itself here and different than any of the tracks they go to is very important,” Allen said. “Having said that, it’s equally important … to make sure that the fan experience part is unique.”

Kyle Larson, who won last year’s Cup race at Auto Club Speedway, said that he talked to Allen on Saturday was told the track project likely will take about 18 months. 

“I don’t know exactly the extent of what they’re doing with the track, how big it’s going to be, the shape or banking and all that, and I love the 2-mile track, but I think the more short tracks we can have, the better off our sport is going to be,” Larson said.

With Auto Club Speedway off the schedule in 2024, it would mean the only time Cup raced in the Los Angeles area would be at the Los Angeles Memorial Coliseum. NASCAR has a three-year contract with the Coliseum to race there and holds the option to return.

Sunday’s Busch Light Clash at the Coliseum marks the second year of that agreement. Last year’s inaugural event at the Coliseum drew about 50,000 fans. NASCAR has not publicly stated if it will return to the Coliseum next year.

Sunday Clash at the Coliseum: Start time, TV info, race format


LOS ANGELES – NASCAR is back and back at the Los Angeles Coliseum.

Nearly three months after Joey Logano won the Cup title at Phoenix, Cup drivers return to action this weekend to run the Busch Light Clash at the Coliseum exhibition race on Sunday night.

This marks the second consecutive year the series has raced inside the Coliseum, which has hosted the Super Bowl, World Series and Olympics.

Details for Sunday’s Busch Light Clash at the L.A. Memorial Coliseum 

(All times Eastern)

HEAT RACES: There will be four 25-lap heat races. Caution laps do not count. The top five from each race advance to the Busch Light Clash. The first heat race is scheduled to begin at 5 p.m.

LAST CHANCE QUALIFIERS: There will be two 50-lap qualifiers for drivers who did not advance to the Clash through their heat races. Caution laps do not count. The top three finishers in each of the qualifiers advance to the Clash. The 27-car Clash lineup will be finalized by adding one provisional spot for the driver highest in points last season not yet in the Clash field. The first of these two last chance qualifying races is scheduled to begin at 6:10 p.m.

CLASH STARTING LINEUP: To be set by heat races and the Last Chance Qualifiers. Winner of heat 1 will start on the pole for the Clash. Winner of heat 2 will start second. Winner of heat 3 will start third. Winner of heat 4 will start 4th. Runner-up in heat 1 will start fifth and so on.

PRERACE: Cup garage opens at 11 a.m. … Driver intros are at 7:50 p.m. … Invocation by Judah Smith, lead pastor of Churchome, at 8:07 p.m. … The USC Trojan Marching Band will perform the national anthem at 8:08 p.m. … Actor Rob Lowe will give the command to fire engines at 8:15 p.m. … The green flag is scheduled to be waved by USC quarterback and Heisman Trophy winner Caleb Williams at 8:20 p.m.

DISTANCE: The Clash is 150 laps (37.5 miles) on the 1/4-mile short track.

STAGES: There will be a stage break at Lap 75 (halfway in the Clash). Wiz Khalifa will perform during the break.

TV/RADIO: Fox will broadcast the event, beginning at 4 p.m. . … Motor Racing Network coverage begins at 4:30 p.m. and also will stream at mrn.com. SiriusXM NASCAR Radio will carry the MRN broadcast.

FORECAST: Weather Underground — Partly cloudy with a high of 63 degrees and a 1% chance of rain for the start of the heat races. Partly cloudy with a high of 61 degrees and a 1% chance of rain for the Clash..

LAST TIME: Joey Logano held off Kyle Busch to win the inaugural Clash at the Coliseum. Austin Dillon placed third. .

Catch up on NBC Sports coverage

New NASCAR season features several changes

Clash at the Coliseum provides a reset for RFK Racing 

Harrison Burton looks for progress in second year in Cup

Dr. Diandra: Muffling racecars won’t change fan experience

Drivers to watch at Clash in Coliseum

NASCAR announces rule changes for 2023

NASCAR outlaws Ross Chastain Martinsville move

NASCAR eliminates stage breaks for Cup road course events 

Looking back on 10 historic moments in the Clash


NASCAR Saturday schedule at Los Angeles Memorial Coliseum


NASCAR drivers are scheduled to hit the track today in competitive mode for the first time in 2023.

Practice is scheduled from 6-8 p.m. on the oval inside the Los Angeles Memorial Coliseum. Single-car qualifying for Sunday’s Clash at the Coliseum is scheduled to begin at 8:35 p.m. (ET). The 36 drivers will be divided into three 12-driver groups for practice.

Cup practice groups

Cup qualfying order

Saturday’s qualifying will set the starting lineups for Sunday’s four 25-lap heat races. The top five finishers in each heat race will advance to the main event. Two 50-lap “last chance” races will follow, and the top three finishers in each of those events will join the feature field.

The 150-lap main event is scheduled at 8 p.m. (ET) Sunday.

For the second consecutive year, the Clash is being held on a purpose-built track inside the LA Coliseum, one of sport’s iconic venues. Joey Logano won last year’s race and last year’s series championship and will be among the favorites Sunday.

Los Angeles Memorial Coliseum


Saturday: Intervals of clouds and sun. High 71.

Saturday, Feb. 4

(All times Eastern)

Garage open

  • 2 – 11:30 p.m. — Cup Series

Track activity

  • 6 – 8 p.m. — Cup practice (FS1, Motor Racing Network, SiriusXM NASCAR Radio)
  • 8:35 – 9:30 p.m. — Cup qualifying (FS1, MRN, SiriusXM NASCAR Radio)

New NASCAR Cup season features several changes


While NASCAR looks back in celebrating its 75th season, there’s plenty new for the sport heading into the 2023 campaign.

Driver moves and schedule changes and are among some of the big changes this year. Here’s a look at some of the changes this season in Cup:


— Two-time Cup champion Kyle Busch has a different look, as he moves from Joe Gibbs Racing to Richard Childress Racing, taking the ride formerly occupied by Tyler Reddick. 

— Tyler Reddick goes from Richard Childress Racing to 23XI Racing, taking the ride formerly occupied by Kurt Busch, who was injured in a crash last summer and has not returned to competition.

Ryan Preece goes from being a test driver and backup at Stewart-Haas Racing to taking over the No. 41 car formerly run by Cole Custer, who moves to the Xfinity Series. 

— Seven-time Cup champion Jimmie Johnson returns to Cup after running the past two seasons in the IndyCar Series. He’s now a part owner of Legacy Motor Club and will run select races for the Cup team. Johnson will seek to make the Daytona 500, driving the No. 84 car.

Ty Gibbs goes from Xfinity Series champion to Cup rookie for Joe Gibbs Racing.

Noah Gragson goes from Xfinity Series title contender to Cup rookie for Legacy Motor Club (and teammate to Jimmie Johnson).

Crew chiefs

— Keith Rodden, who last was a full-time Cup crew chief in 2017 with Kasey Kahne, is back in that role for Austin Dillon at Richard Childress Racing, as Dillon seeks to make back-to-back playoff appearances. Rodden comes to RCR after working with the Motorsports Competition NASCAR strategy group at General Motors.

— Chad Johnston, who has been a crew chief for Tony Stewart, Martin Truex Jr., Kyle Larson and Matt Kenseth, will serve as crew chief for Ryan Preece at Stewart-Haas Racing.

— Blake Harris goes from being Michael McDowell’s crew chief at Front Row Motorsports to joining Hendrick Motorsports to be Alex Bowman’s crew chief. 

— Mike Kelley, who served as Ricky Stenhouse Jr.’s crew chief when Stenhouse won Xfinity titles in 2011 and ’12, returns to the crew chief role with Stenhouse this season at JTG Daugherty Racing. 


— What’s old is new. The All-Star Race moves to North Wilkesboro Speedway in May, marking the first Cup event at that historic track since 1996.

— July 2 marks debut of the street course race in Chicago, marking NASCAR’s first street race for its premier series.

— The spring Atlanta race and playoff Texas race have both been reduced from 500 miles to 400 miles.


Ross Chastain’s video-game move on the last lap at Martinsville will no longer be allowed, NASCAR announced this week. 

— Stage breaks are gone at the road course events for Cup races. Stage points will be awarded but there will be no caution for the end of the stage.  

— If a wheel comes off a car while on track, it is only a two-race suspension (last year it was four races) for two crew members. The crew chief is no longer suspended for the violation. 

— Cup cars have a new rear section that is intended to absorb more energy in a crash to prevent driver injuries after Kurt Busch and Alex Bowman each missed races last year because of concussion-related symptoms.

— Elton Sawyer is the new vice president of competition for NASCAR. Think of the former driver as the new sheriff in town for the sport.


— With a win this season, Kyle Busch will have at least one Cup victory in 19 consecutive seasons and become the all-time series leader in that category, breaking a tie with Richard Petty.

Denny Hamlin needs two wins to reach 50 career Cup victories. That would tie him with Hall of Famers Ned Jarrett and Junior Johnson for 13th on the all-time list. 

Kevin Harvick, running his final Cup season, is 10 starts away from 800 career series starts. That would make him only the 10th driver in Cup history to reach that mark.