New Wave Sports Cars
Road & Track
By Sam Mitani Photos by Guy Spangenberg and Koichi Ohtani
Mazda got the wheels rolling with the notion of new-wave sports cars when it introduced the RX-8. Traditionalists will maintain that a sports car can't have four doors by virtue of its definition, but many, including me, believe that Mazda successfully executed the premise in the form of the RX-8. But in many enthusiasts' eyes, the stock RX-8 was still short of perfect. For one, some felt that the suspension of the car was tuned too soft. The car tended to take on a floaty nature when traveling over crests and dips, and body roll became pronounced on high-speed right/left transitions. Despite the linearity of the rack-and-pinion steering and the exceptional rigidity of the chassis, a certain amount of finesse is required to guide the car smoothly and quickly around a racetrack.
"Because it's a true 4-seater, we felt it should have adequate touring capabilities. We didn't want to make the car so stiff and rigid that it becomes a burden on long drives," Shiro Yoshioka, product chief, said. "For the purists, we will offer another version of the car."
That version, we discovered, is the Mazdaspeed RX-8.
On a cold winter day just outside Hiroshima, Japan, Yoshioka and his team of engineers invited me to sample a prototype Mazdaspeed RX-8. The car was rolled out straight from the research and engineering center onto the test track at Miyoshi, and they informed me that the engine tweaks had just been completed. Engine tweaks? "You're going to give it more power?" I asked enthusiastically.
"Not really," Yoshioka replied. "Our main goal was to give it better throttle response. We were able to give it a little more torque as well."
The nature of the Renesis rotary engine is such that peak horsepower isn't realized until very high in the rpm spectrum, and there's very little torque down low, thus making it difficult to extract the full potential of the rotary in everyday driving. Where some of us were expecting something along the lines of the RX-7 powerplant, we instead got something more akin to the high-strung inline-4 of the Honda S2000 (not a bad thing if you're into revs). Although Yoshioka wouldn't comment, sources close to the company said that the North American arm of Mazdaspeed is currently working on a supercharged version of the RX-8. There's even rumor of a hydraulic turbocharger, which uses a hydraulic pump instead of exhaust gases to spin the turbine.
"There are a number of possibilities we're still exploring," Yoshioka said. "The life cycle of the RX-8 is a long one so we want to gradually enhance the car. This car is the first step."
With that, he invited me to slide into the driver's seat. As soon as I stepped on the throttle, I could feel the difference in this rotary's character. It revs so smoothly and quickly that you reach the rev limiter in a snap of the finger no doubt the result of a new lightweight flywheel. The rotary's breathing has also been significantly improved slight modifications to the intake and a new exhaust system result in a better-sounding rotary with a bit more oomph. Although we get only about a 10-bhp boost in horsepower, the improvements in throttle response and midrange torque are immediately perceptible from the driver's seat.
So, too, is the car's improved handling.
The first thing you notice when taking a corner is the stability of the entire chassis. Turn-in response is crisp and body roll is all but absent. Mazdaspeed engineers lowered the RX-8 about three-quarters of an inch, and then fitted firmer tube shocks and coil springs, as well as fatter anti-roll bars. Also, they gave the already stiff RX-8 chassis more rigidity by installing strut tower braces both front and rear and a couple of crossmember braces beneath the car. It may seem as though Mazdaspeed chassis engineers went overboard improving the handling of the car, but one may interpret this as a prelude to more power. This car officially goes on sale in Japan as you read this, but all 350 that have been built were sold before Christmas. We get our version either later this year or in 2005. I would say it's safe to expect a meaner, faster version.
Further in the future is the Hydrogen RX-8. The more Masanori Misumi, the senior research engineer of the technical research center, explained the system, the more I became convinced this could be the ideal alternative-fuel sports-car powerplant. The system in the RX-8 is a hybrid that uses both gasoline and hydrogen. By flipping a switch on the dashboard, you go from one to the other.
In gasoline mode, you get the same performance and output of the 210-bhp Renesis. In hydrogen mode, you get about half the power output of "gasoline" mode (110 bhp) adequate for around-town commuting but with zero emissions. All that comes from the exhaust is water vapor. Otherwise, the sound and function of the rotary is no different.
Mazda has long maintained that the rotary engine's unique character is a custom fit for hydrogen power. Misumi explains:
"With conventional engines, we discovered quite a bit of backfiring because the element is more combustive than petrol. There were also problems with the way hydrogen reacted when it was injected through intake valves. With the rotary you erase those problems. Right now, our main obstacle is storage. You need more storage space with hydrogen than with gasoline, and as you can see in the RX-8, there's really not that much space to hold a big hydrogen tank."
Converting the rotary into a hydrogen-burning engine is relatively simple. Drill a couple of extra holes in the rotary housing, incorporate a delivery system and reprogram the timing. That's about it; therefore, a hydrogen-powered RX-8 shouldn't cost that much more than a "normal" version. The development of the hydrogen-powered car is further along than I had thought. There are several hydrogen refueling stations around Japan with a few runners in use by post offices, government officials and the like. Misumi believes that we should start seeing hydrogen-powered cars from Mazda as early 2007. Let's hope among them is the RX-8.
Mazdaspeed RX-8 Specifications
Curb weight est 3200 lb
Wheelbase 106.3 in.
Length 174.2 in.
Width 69.7 in.
Height 52.1 in.
Engine & Drivetrain
Engine 1308-cc 2-chamber rotary
Valvetrain 3 intake & 2 exhaust side ports per rotor chamber
Compression ratio 10.0:1
Horsepower est 250 bhp @ 7200 rpm
Torque est 165 lb-ft @ 5000 rpm
Transmission 6-speed manual
Chassis & Body
Layout front engine/awd
Brake system 12.8-in. vented discs/ 12.4-in. vented discs; ABS
Wheels 19 x 8JJ
Tires Bridgestone, 225/55R-19
Steering type rack & pinion
Suspension, f/r MacPherson struts, coil springs, tube shocks, anti-roll bar/struts, coil springs, tube shocks, anti-roll bar