Maximum Miata

Unleashed in 1989  as a reliable and modernized interpretation of the 1967-1975 Lotus Elan, Mazda’s Miata roadster entered an automotive environment filled with front-drive econoboxes and floppy convertibles. A bold gamble at the time, perhaps, but it worked sensationally, and total sales of the 2-seat roadster have now edged toward nearly 1 million, substantially more than any other sports car ever made. Besides generating such impressive sales numbers, though, the car has also inspired a new generation of hot-rodders following that purely American tradition of squeezing a big V-8 engine into a lightweight car. A modern-day AC Cobra? Essentially, yes.

Four companies, including Racing Beat, V-8 Roadsters, Monster Miata and Flyin’ Miata, have supplied the most fanatical Miata fans with high-horsepower V-8 engine conversions to make their cars quicker. Yet, Porsche fanatic Bill Cardell’s Flyin’ Miata folks in Colorado have produced a car so sublime and well refined that one enthusiast called it, “The best car we’ve driven all year.” And it’s important to mention that he had also driven a Ferrari Enzo, a McLaren F1 and Lamborghini’s new Huracán LP 610-4.

Flyin’ Miata is an evolution of the commercial garage Cardell opened in 1983. The company now sells kits to turbocharge and supercharge Mazda’s roadster darling, as well as a wide variety of suspension and brake upgrades many of which he has developed and tested himself. Why? “To answer the question, ‘How much is too much?’” Cardell laughs. And true to hot-rod form, he has not yet completely answered this riddle.

Thankfully, the rear-drive, independently sprung 167-hp Miata is a solid base for improvements, from wildly increasing power levels to fully reinforcing the unibody to absorb heavy pavement punishment. The pinnacle of Cardell’s work is found in today’s $43,000 installation of a 430-hp aluminum Corvette V-8 into a Miata. That price, incidentally, is just for the conversion work. If you add in the cost of a new Miata, the entire package costs $8000 more than a Corvette convertible. If you have to ask why not just buy the Corvette in the first place, you’re missing the concept of Yankee creativity. Plus, the Miata is more nimble and just plain more fun. As proof, independent testing showed a new 480-hp Flyin’ Miata V-8 conversion (Flyin’ Miata also offers a 430-hp and a 525-hp version of the V-8 engine with its kit) matched the Corvette’s 0–60 mph time of 3.8 seconds. A stock Miata takes more than 6 sec. to reach the same speed.

In truth, the Flyin’ Miata “Habu” (the Japanese word for venomous snake, which the company nicknamed its V-8 car), was not the first to the killer Miata party. Although it was born in 2002, in the desolate, wide-open suburb of Palisade, Colorado, just outside of Grand Junction, other Monster Miatas with Ford V-8s preceded it.

The first appeared about three years after the roadster debuted in 1989, but driveability wasn't as faultless as in the stock sports car, and the losses in balance created by adding the heavy Ford 302 engine sometimes outweighed the gains in brute power. Also, Flyin’ Miata doesn’t limit itself to the V-8s; it has always sold many more turbo and supercharger kits to Miata owners who are starved for power but don’t want to go completely berserk.

Frog Arms beef up the unibody frame of early model year Miatas, keeping reinforcing the structure under the forces of a high-torque V-8 engine. The all-aluminum GM LS3 V-8, available from 430 to 525 hp, fits inside the Miata engine bay almost as if it was designed for it.

Lowered springs and larger tires and wheels give away that the big power V-8 conversion is aboard. So does the sound of the custom stainless steel exhaust system (with emissions-friendly catalytic converters), which adds a low rumble that you feel more than hear. The clutch that attaches to the GM V-8 is very stiff, unlike the Miata’s stock unit, and the shifter is not the light little Mazda-tuned stocker that is a favorite. But that’s about all you give up for the power.

The most modern Miata unibody, introduced in 2005, is larger and stiffer than the two previous generations, and it gives up some of the light-feeling delicacy of the early cars, which need to be modified by welded chassis braces essential according to Cardell. The late-model Miatas also weigh more than 2800 lb. with the V-8 conversion (a new Corvette convertible weighs about 3500 lb.). Because the Chevy engine is aluminum, it doesn't affect the weight distribution much, which preserves the excellent Miata balance. Cardell explains that even with the GM V-8 and a new
6-speed manual transmission, the weight distribution of the Miata remains at nearly 52 percent over the front wheels.

Creeping along with the tall final drive ratio on the highway means you can nearly achieve the 30 mpg that a Corvette is tuned to deliver, but when you use all the power, the fuel economy drops to the level of a much heavier car. Blazing speed is never a free lunch.

Hot-rod V-8 Miatas are fairly rare, Cardell admits, and in the past decade the company has sold only 30 ready to run converted cars; although, they have a steady little stream of orders to build more. In contrast, the company has sold more than 100 kits for do-it-yourself customers, with a few going to Europe and Australia.

Building a hot-rod V-8 Miata the right way is not a task for the typical weekend mechanic. “Most customers select our optional seam welding, where we MIG-weld critical unibody seams that are only spot welded from the factory,” Cardell notes. “This makes a substantial difference in solidity. We also use Frog Arm braces under the front fenders. The kits come with frame rail reinforcements, and we additionally offer bulkhead reinforcements to weld into the firewall area.”

The V-8 engines require changes to their control computers for timing and air/fuel ratios to get them to run smoothly in the Miata, and the stock Mazda fuel pump must be replaced with a higher flow GM unit so it won’t starve the engine when it’s working hard.

Custom stainless exhaust system fits tightly from the tubular steel subframe added to hold the V-8 all the way to the rear. An aluminum-bodied Cadillac CTS rear differential is necessary to handle the V-8 torque and mate to a larger 1-piece driveshaft (not shown) and upgraded halfshafts.

Flyin’ Miata’ kits include parts built by V-8 Roadsters in Tennessee. These include special half-shafts and a 1-piece driveshaft, which are necessary to attach the new transmission and rear differential to the existing wheel hubs on the Miata. A tubular steel front subframe, also made by V-8 Roadsters, must be added to the existing Mazda frame; it supports the engine as well as the front suspension
and steering rack. Cardell credits V-8 Roadster’s founder Steve Leonard with producing good pieces.

Flyin’ Miata then adds engine-mounted heat shields, new fuel lines and a complete exhaust system to make their kit thorough. The kits include steel braces that must be welded between the firewall and the front frame rails, as well as a brace that is bolted between the front shock absorber upper mounting towers. Early models of the cars that Flyin’ Miata converted for customers additionally had their front frame sections cut and widened, says Cardell, and then seam-welded and painted.

The V-8 Miata that most recently impressed the experts included upgraded brakes 6 piston Brembo calipers that Cardell says most customers now insist on. In addition, all of the ready to run V-8 Miata conversions have their suspensions upgraded with firmer springs and more controlled shock absorbers.

“The beauty of this conversion is that the car remains a Miata with all the great attributes that implies, including excellent balance, great handling, light weight and reliability,” Cardell says. “And then turns it up to 11.”