Many folks would be satisfied — maybe a little scared — with a turbocharged Miata track car making somewhere in the vicinity of 400 horsepower. However, Ryan Raduechel grew up racing Thunder Roadsters and has a penchant for excess, so the 2022 Thunder Roadster National Champion was comfortable reaching for more.
Over the 12 years Raduechel has spent modifying this Miata, he’s altered its course several times in pursuit of low-maintenance lapping. Though his eyes were once bigger than his stomach, he’s grown to be a more measured, level-headed racer with an appreciation for what really matters in a racecar.
While Ryan was enrolled in junior college, he grabbed this 1990 Miata for a cheap, simple source of excitement. It didn’t hurt that the Miata was economical enough to serve him as a daily driver, though his aims were always to make it into a seriously quick track car.
Because he was a tough 20-year-old with a willingness to endure some discomfort, he didn’t mind making many concessions for speed at this point. It didn’t take long before he installed a set of budget coilovers as well as an Autopower bolt-in roll cage, which did little for his peace of mind.
Standing 6’ tall, Ryan wasn’t really comfortable in the car before the scaffolding was installed, and having his eyes inches from the cage’s protruding bolts were constant sources of consternation. He eventually he scrapped the bargain bolt-in and splurged on a custom cage that, in addition to stiffening the chassis, gave him a little more room because it was built wider to take advantage of the space freed up by removing the door cards. From casual roadster to caged track rat in a few months, this Miata was rapidly transforming into something that had no business on public roads.
Half a dozen lackluster track days with the car in this near-stock configuration had Ryan thinking that only a no-compromise track build would satisfy. He bought a more comfortable means of transportation, registered the Miata as a non-op, installed a set of Butler aluminum seats, and went down the often irksome route of turbocharging the BP engine.
Like so many youngsters, Ryan set off in pursuit of big numbers and opted for a turbo that the 1.6-liter would struggle to spool. The 359 horsepower produced by the Garrett T3/T4 turbo came with two major setbacks: its power band was 1,500 rpm wide and the factory gearbox would not handle it. In fact, Ryan went through four gearboxes in the first year of forced induction. That was all the time it took him to recognize that there must be a better way — one with fewer headaches and more power.
This was when his M.O. received an update. Though he knew the Miata was destined for the track, it needed a specific designation. Rather than make it a quick car capable of 20-minute lapping sessions, he decided to go all-out in making it a supremely fast, high-horsepower, low-stamina special. This time attack machine would be good for five or six laps at a time, but those laps would be riveting.
Taking the First Left Turn
To achieve that sort of excitement would require a larger motor, and a 5.3-liter LM7 fit the budget. Being iron-blocked, it would also handle boost better than its aluminum counterparts. Attached to the new GM lump were a set of homemade turbo manifolds, an On3Performance 88mm turbo, an LS1 intake manifold, a Tial 60mm wastegate and blow-off valve, Deka 80-lb injectors, an Aeromotive fuel pump and fuel pressure regulator, and a Holley ECU to tie it all together. Tuned on E85R, the new motor pumped out the figures Ryan felt a time attack car ought to have: 721 horsepower and 693 pound-feet of torque at the rear wheels.
Of course, no factory Mazda gearbox could wrangle that horsepower. In the place of the OEM five-speed went a Tex Racing T101 four-speed dogbox, sandwiched between a McLeod twin-plate clutch and a Ford 8.8” rear end.
The first test with this little monster revealed that monstrous power always comes at a premium. Perhaps choosing a mid-summer track day at Thunderhill West for the shakedown was not the ideal setting for such a powerful machine, but even an outing at Willow Springs in winter would’ve illuminated the car’s myriad problems.
The main issue was cooling. Regardless of the scoops and various ducting he’d already installed, the engine continued to overheat. Running a spool hampered its performance in hairpins, and the traction, though fairly good, could still overwhelm the 275/35-15 Hoosier R6s wrapping his Jongbloed wheels. At least his Wilwood four-piston calipers handled the abuse.
He left that day with a long face, but focused on another test just a month away. The 2019 Mazda Miata Reunion was held in early October at WeatherTech Raceway Laguna Seca. Hopefully, the cooler seaside temperatures and longer straightaways would allow this little monster to shine.
Five laps in and Ryan hit trouble. The motor started knocking in the Corkscrew, so he rolled it down the hill into the paddock, where it seized. At least he’d proven the car’s potential with a 1:37 — on old tires, no less — before it gave up.
Heading into that winter, Ryan was not at his happiest. In fact, he spent most of his free time kicking himself over having taken so many shortcuts with the build. A budget turbo, a rear-mounted radiator, and a cheap spool restricted the little Miata. Driven by his disappointment, he pulled out his credit card and started picking out a few new items from the top shelf.
While the Penske coilovers and BorgWarner turbocharger were enroute, he started hacking away at his rapidly evolving project. To address the cooling limitations, he chopped the front end off ahead of the shock towers and replaced it all with a tube-frame arrangement. This freed up the real estate needed to put the radiator up front and route all the ducting needed to keep things cool.
The new turbo kit was nearly completed when Ryan asked a local shop to cover his headers in a ceramic coating. The $4,000 quote turned his stomach, and had him questioning his recent spending spree.
“I realized then that there’s a line that separates reasonable and whatever the hell I was doing,” he said.
A Change of Heart
This was his Road-to-Damascus moment. He recognized that as appealing as this all-out time attack car might be, the effort required to keep one running was more than he was interested in making. He decided he would instead build something that worked more of the time, provided him with adequate straight-line speed, and, most importantly, would allow him to compete in fields with 20 other cars.
He started putting the car on a serious diet the moment he chucked the turbocharger and all the ancillaries. Then, without a need for such a stout bottom end, he exchanged the iron block for an aluminum L33. Sourced from a Trailblazer SS, this block shed another hundred pounds from the front end. After ditching the pop-up headlights and adding a Treasure Coast fiberglass hood, he helped bring the weight distribution back to something a little more Miata-like. Well, 55% in front is not ideal, but at least he wasn’t dealing with an iron anchor over the front axle any longer.
The aim was no longer horsepower. Now it was reliability. With ARP hardware, Wiseco pistons, a Summit .625 cam, COMP Cams’ springs, pushrods, and rocker arms, and a Megasquirt MS3 ECU for a conservative tune, he estimated it was making about half of what it formerly made, but the sturdiness of this dependable powerplant would far outweigh any straight-line shortcomings.
This new powerplant helped reduce the overall weight to just over 2,400 pounds — a difference of 250 pounds. With cornering speed taking a higher priority, he widened the footprint with a set of 15” x 11” Jongbloed wheels wrapped in 295-section Hoosier A7s, built his own upper and lower control arms and fitted them with spherical bearings, installed an AVIAID dry-sump system, added a set of splined sway bars, and got to work on the long-overdue aerodynamics package.
Air flows over the carbon hardtop to the Kaze Spec 72” carbon wing. Up front, he added a HDP plastic air dam, a plywood splitter, and a quick-change aluminum frame behind the bumper, which allows the entire front end to be removed by pulling a few pins. Ryan had once yearned for a complicated, overpowered car. Now he craved something he could lean on without much wrenching.
With more grip, he had to consider two things: the flimsiness of the factory hubs and the reality of counter-steering a car on massive slicks. He replaced the hubs with stronger billet items from BroFab, then added an adjustable electronic power steering setup from EPowerSteering.
No longer able to mask handling deficiencies behind a wall of turbo torque, the car would require a lot more fine-tuning before it was anywhere near its potential, but the basic recipe proved to be more than adequate. Even before it was dialed in, Ryan entered the V8 Miata in a Super Unlimited race at Sonoma, where it finished P2 behind a Radical SR8. Now capable of 1:45 laps there, the Mazda hadn’t been slowed much by halving the power. Even better, he never had to open the hood all weekend. He’d clearly picked the right path.
After that event, he dyno-tested the car to slot it neatly into its proper category. The newer, lighter engine makes a healthy 354 horsepower and 351 pound-feet of torque — putting it squarely in ST1 pack. To corroborate his pace-related guesses, he took it to Laguna for a NASA lapping day. His 1:33 time lands him squarely in the middle of the ST1 pack there.
The reason for his remarkable speed? Well, having over a decade of Thunder Roadster experience helps — as does the predictable handling balance and great traction.
“You don’t have to fight it. It won’t spin the wheels much until the tires fall off,” Raduechel said. “When they do, you can increase the power steering for easier countersteering.”
“I’d never really raced something with an LSD and aero before, but it wasn’t hard to adjust to. I don’t have to pitch it in sideways like I will in a Thunder Roadster — it just works!”
Now that winter is upon us, Ryan has started ordering parts to make next season fruitful. To get his car to lap Laguna Seca in the 1:30-range, he has a little tuning to do and a few major parts to purchase.
The biggest item on his list is a Winters Performance quick-change rear end, which will make fine-tuning of the differential and final drive swaps as easy as possible. Minimized strain is the aim these days.
It’s easy to get carried away with a big-number build that will scare the driver and stun bystanders, but as one develops as a driver and a builder, he or she begin to value different things. A willingness to modify one’s M.O. and a tempered, pragmatic approach usually pay off. They certainly help keep a driver’s rear in the seat more of the time, as Ryan’s experience illustrates. If he’s learned one thing from this wild ride, it’s this: don’t bite off more than you can chew.
