Bulletproof skin, superhuman strength, lightning-fast reflexes, heat vision…flight? When Jerry Siegel and Joe Shuster dreamed up Superman back in 1938, they didn’t leave much ammunition for the bad guys to work with. So, when a 1970 Challenger named after the superhero’s only weakness—“Kryptonite”—rolls onto the scene, it better pack one heck of a punch. And we’re here to tell you that this searing green E-body has what it takes to make The Man of Steel look like just another mild-mannered Clark Kent.
We caught up with Kryptonite at the latest Summit Racing Equipment photoshoot, where this muscled-up restomod was preparing to grace the cover of an upcoming catalog. Between the shots, we were fortunate enough to get its full origin story straight from the owner, Mark Brownfield, along with the builder, Kevin Tirpak.
“I always wanted a muscle car but I could never afford one,” explains Mark. “I got married young, had kids, and started my own business. Later on, I picked up a Ford Galaxie—but that was just a driver—and this was my second car.” Long before assuming its sinister alter ego, Kryptonite, this first-gen Challenger rolled off the assembly line wearing Dodge’s vibrant Sublime Green paint and a comparatively sedate 340 Six Pack under the hood.
“The project started as just a fresh paintjob,” recalls Mark. “A friend of mine had Kevin do a couple cars for him, and I was very impressed with his work.” Kevin Tirpak, the chief wrench-turner at Altered Motion in Ravenna, OH, is no stranger to custom builds. His resume includes all manner of resto jobs and one-off creations, so when Mark came back with a couple more requests, it was just another day at the shop for Kevin.
“The car was just about ready for paint and I thought it would be neat to try a Hellcat motor. This was right after the Hellcat had come out, so you weren’t seeing that swap in everything,” says Mark. Their version of the Dodge’s 6.2L Hemi comes topped with a burly 2.9L Whipple blower, pumping an estimated 850 hp through a Tremec T-56 Magnum six-speed—that’s enough grunt to get anyone’s tights in a twist!
“There was no way the stock frame was going to handle the additional power,” says Mark. “I did some looking around and was pretty impressed with what the Roadster Shop had to offer, so we went with their Fast Track chassis.” The setup features an independent front and rear suspension with boxed frame rails (a far cry from the stock leaf springs and torsion bars), all of which Kevin tucked three inches inside the Mopar’s body, contributing to the car’s hyper-aggressive stance.
Penske Racing coilovers, Baer big brakes, and staggered Forgeline GZ3 wheels wrapped in Michelin Pilot Sport rubber round out the handling modifications.
Of course, what good are those mountainous muscles and fancy moves if you don’t have a flashy outfit to bring it all together? “It was actually our upholstery guy who suggested we take this car to the next level,” says Kevin. “He’d done some work for a few other cars that had made it to the Great 8, and he convinced us the Challenger could compete at that same level. That’s when we decided to go for it.”
With their sights set on the Ridler Trophy—the Detroit Autorama’s top honor—Kryptonite’s bodywork took center stage. Shaved drip rails, door handles, and marker lights, plus flush-fitting glass and bumpers all contribute to the midsize Mopar’s sleek look.
More noticeable, however, is the Challenger’s custom hood. “Our goal was to mimic the look of an AAR ′Cuda,” explains Kevin. “The supercharger sticks up almost nine inches from the top of the fenders, so I had to custom-make the scoop to clear it.” And equally impressive is the electrically actuated front-tilt mechanism that whirs to life at the push of a button.
“When we debuted it at Detroit, people joked that the reason we showed it with the hood open was because it doesn’t close, but it does! We demonstrated it many, many times at the show.”
But the visual flair doesn’t stop there.
Living up to its namesake, Kryptonite’s custom PPG “Chameleon Green” paint practically glows against the matte green accents and Hugger Orange pinstriping, all laid down by none other than Kevin. “I told Kevin I wanted it to be so this car would stand out against all the other cars at a show,” says Mark. “And he did it! I remember when we first got to Detroit, we could spot it all the way at the other side of the convention center!”
Inside, Kryptonite takes its inspiration from modern Mopars, sporting a 2016 Hellcat dashboard and console wrapped in black leather and suede with orange stitching, plus matching Corbeau buckets all courtesy of Sean O’Neill of Spotlight Customs in Akron, OH. Other highlights include a Billet Specialties Prizm steering wheel and ididit column, pistol-grip Sikky shifter, and a Holley 12.3 inch Pro Dash talking to the Dominator ECU.
With the build complete just in time for the 2022 Summit Racing Show Car Series, Mark and Kevin have had no trouble snatching up some of the show scene’s most precious hardware, including a Great 8 finish in Detroit, a top spot at the 2022 Columbus Goodguys Summit Racing Nationals, and most recently the award for Outstanding Street Machine at the 2023 Chicago World of Wheels.
It looks like Superman isn’t the only one who goes weak around Kryptonite!
1970 Dodge Challenger “Kryptonite” Fast Specs
Owner: Mark Brownfield, Builder: Kevin Tirpak
- Dodge 6.2L Hellcat Mopar crate engine with 6.4L accessories and valve covers
- Whipple 2.9L supercharger
- Lingenfelter Performance supercharger pump with Killer Chiller supercharger cooler
- Griffin Performance Fit radiator and fan combo
- Custom stainless steel headers and 3″ dual exhaust
- Exhaust by Joe Barstow, After Hours Fab & Performance
Transmission & Driveline
- Tremec T-56 Magnum 6-speed transmission
- QuickTime bellhousing
- Hays billet steel flywheel
- RAM Force 10.5 Dual Disc clutch
- Ford 9″ third member
Ignition & Electronics
- Holley Dominator EFI vehicle management system and engine harness
- Holley 12.3″ Pro Dash
- RacePak Smartwire power control module
Chassis & Suspension
- Roadster Shop Fast Track complete chassis, tucked 3″ inside body
- Custom roll cage
- Penske Racing coilover shocks
- Baer Brakes disc brakes
Wheels & Tires
- Forgeline GZ3 three-piece forged wheels, 18″ x 9″ (front), 19″ x 12″ (rear)
- Michelin Pilot Super Sport tires, 255/35ZR18 (front), 345/30ZR19 (rear)
- Shaved drip rails, door handles, and rear marker
- Custom front-tilt hood with BEYOND electric actuators
- Custom grille and front splitter
- Oracle LED headlights
- OE Dodge Challenger LED taillights
- Custom rear spoiler
- Flush-mount front bumper and roll pan
- Electrically actuated trunk lid
- Flush-mounted windshield and rear window,
- Floor lowered 3″
- Custom cowl panel, firewall, core support, inner front fenders
- Relocated fuel door and custom fuel tank
- Custom engine and radiator covers
- Custom PPG Deltron “Chameleon Green”
- Matte green accents, Hugger Orange pinstripe
- Dodge Challenger Hellcat dashboard and console
- Custom interior and trunk panels
- Corbeau seats
- Custom black leather and suede upholstery with hugger orange stitching
- Braum Racing 5-point harnesses
- ididit Universal steering column
- Billet Specialties Prism steering wheel
- Sikky shifter with pistol grip handle
- Vintage Air heater and air conditioning
- Pioneer audio system
- Interior by Sean O’Neill, Spotlight Customs