Doug Rose drives Walt Arfons’s Green Monster, the world’s first jet dragster, which was built in 1959. (Courtesy of Akron Beacon Journal)

Walt Arfons, a self-taught mechanical engineer and champion drag racer who built the first jet-engine dragster, conceived of innovations that helped save lives on the raceway, and had a car that held the land-speed record at 413 mph until his estranged half-brother bested it three days later, died June 4 at a hospital in Akron, Ohio. He was 96.

The cause was pneumonia, his son-in-law Richard Stiff said.

Mr. Arfons and his younger sibling Art, both irrepressible daredevils and showmen, were among the best-known drivers during drag racing’s infancy in the 1950s and its propulsion into mainstream news coverage in the 1960s. Along with Craig Breedlove, they were leaders in fierce battles to attain ever-increasing land-speed records at the Bonneville Salt Flats in western Utah.

Art Arfons, who died in 2007, held three land-speed records and was inducted into racing halls of fame, at times overshadowing his more self-effacing brother. Nevertheless, it was Walt who is credited by many experts with taking motor sports into the jet age and finding ways to make the sports safer.

Louise Ann Noeth, a driver and automotive journalist who has written about the Bonneville competitions, noted that in addition to being the first to apply jet engines to race cars, Walt Arfons is also credited with being at the forefront of adapting parachute technology to motor sports.

Walt Arfons in a 1965 file photo. (Courtesy of Akron Beacon Journal)

“No high-speed car today can stop safely without one,” Noeth wrote in an e-mail. “Walt Arfons spawned an entire safety industry in motorsports. . . . Every time something went wrong with a race car mechanically, aerodynamically or due to driver brain fade, the parachute is the single best friend a race car driver has north of 300 miles per hour.”

Noeth called drag racing “a home-grown American motor sport that challenges the mind to outwit the clock, master mechanics and energize engineering disciplines. Not for everyone, but it is a sport where passion begets dedication that begets the great experiment — it is a wonderful way to research, develop, test and evaluate a plethora of mechanical, engineering, science and technological dreams.”

The Arfons brothers learned how to use and assemble machinery at their father’s feed and hardware store in Akron during the Depression. They built cars from spare parts and, during a boom in surplus airplanes after World War II, they bought planes to tinker with. During their racing years, they would continue to improvise their designs using junked parts.

They participated in their first drag race in 1952 after concocting a makeshift, three-wheeled hot rod from an Oldsmobile engine, the back of a Packard and the landing gear of an airplane for a front wheel. It had such an unappealing green paint job that the race announcer dubbed it the Green Monster. The brothers embraced the name for many of their subsequent machines.

Although their first Green Monster lost, they soon devised a better car that used an Allison P-38 aircraft engine. Attaining speeds of more than 150 mph, they won a series of local races and eventually triumphed at the sport’s most prestigious contest, in Lawrenceville, Ill.

But they soon parted ways over what Walt called a needless and reckless rivalry on the track. The brothers would sometimes split up as racers to improve their chances at taking home prize money, but Walt said Art felt a need to obliterate his brother’s time, even if Walt had all but won the race.

“We had the money already. He was endangering the car and his own life just to beat my time. And he done that so many times. And then I didn’t go back for more because I knew better,” he was quoted in Samuel Hawley’s book “Speed Duel: The Inside Story of the Land Speed Record in the Sixties.”

They didn’t talk for years and became professional foes in the so-called tire wars. Goodyear became Walt’s sponsor, and Firestone was Art’s.

Walt Arfons began to focus on the potential use of jet engines to help break land-speed records. This was a hazardous pursuit, given the widespread fear that marrying jet engines and dragsters would lead the vehicle to spin like a top.

He bought a surplus military jet at auction, but the engine’s manual was classified. So in his shop, he painstakingly assembled a new car around the plane’s turbo-jet engine. From there, it was trial and error. Lots of error.

“Oh my goodness, it scared the hell out of me. I couldn’t believe the horsepower,” he told author Harvey Shapiro. “It’s like you bend over and take a twenty-foot two-by-four and someone smacks you in the butt. It’s quite a sensation, believe me.”

He used parachutes to stop the car because brakes were insufficient at hundreds of miles per hour.

His eldest grandson, Mark Stiff, recalled that the first few times Mr. Arfons tried to use the parachutes, the main and reserve chutes ripped off and the car crashed hard, leaving his grandfather with broken ankles and casts above his knees. The car was totaled.

“I remember he pushed himself around on a creeper” — the device used by mechanics to slide under cars — “with those casts on his legs and he rebuilt the car,” Stiff said. “He had a couple shots of Seagram’s 7 and soaked his casts down in the tub and cut them off. He had to get the car working again. It was how he got bread on the table for his family.”

A later configuration of the jet-powered car — named the Wingfoot Express after the Goodyear logo — broke a land-speed record by zooming 413 mph over one mile on Oct. 2, 1964, at Bonneville.

The glory for Mr. Arfons and his driver, Tom Green, was short-lived.

Three days later, Art Arfons broke the record by going 434 mph in another jet-powered car. The Arfons brothers and Breedlove would joust for speed records over the next few years, seeking to shoot past the 600 mph mark; Breedlove made it in 1965 and held the record for five years.

Walt Arfons was born Walter Charles Stroud on Dec. 10, 1916, in Muncie, Ind. He grew up in Akron and took his stepfather’s surname, Arfons.

A month after his short-lived record in 1964, he designed a jet-powered car in which Paula Murphy broke the women’s land-speed record (226 mph) at Bonneville.

In 1965, Mr. Arfons returned to Bonneville with a $78,000 car that rocket designer Ky Michaelson once described as “a land-locked missile, disguised as a rocket car.” The vehicle used jet-assisted takeoff engines — solid-fuel rockets — that provided thousands of pounds of thrust, and Goodyear designed tires capable of handling speeds over 700 mph.

Ultimately, the rockets did not burn long enough to maintain full speed, and the car could not outdo Breedlove’s 536-mph record.

In the late 1960s, Chrysler approached Mr. Arfons with an offer to soup up some of their cars with jet engines, and he hired several drivers to race them on the Funny Car circuit. He retired from motor sports by the early 1970s.

Survivors include his wife of 75 years, Gertrude Becker Arfons of Uniontown, Ohio; two children, Patricia Stiff of Fairlawn, Ohio, and W. Terry Arfons of Uniontown; a sister; eight grandchildren; and 19 great-grandchildren.

A son, Craig Arfons, died in 1989 when his 5,000-horsepower hydroplane crashed on Lake Jackson in Sebring, Fla., while he was attempting to break a speed record on water.

Art Arfons, who had walked away from several spectacular crashes, took a long break from racing after a 1971 accident that killed three people.

Walt Arfons’s grandson, Mark, said his grandfather’s workshop was his favorite place to play as a child. There were lots of tools, engines were being fired up, and the bone-displacing rattle from the afterburners was unforgettable.

He recalled neighbors did not always appreciate his grandfather’s work. “There was one guy always calling the cops,” he said, “and then the sheriff would arrive and be like, ‘Hey, can you fire it up again?’ ”