Mazda Tests the Turbo Waters

By Feann Torr - 12/10/04

This is what fans of the venerable twin turbo RX-7 have been waiting for - a turbocharged RX-8.

The 177kW output of the naturally aspirated RX-8 endows the lightweight four-door sports car with a very quick 0-100km/h time of just over 6 seconds, but Mazda Australia's motor sport manager, Allan Horsley, came up with the idea of turbocharging the rotary engine, and the results are phenomenal to say the least.

Forget the 211Nm and 177kW of the nat-atmo model, as this extreme concept car kicks out a rubber melting 270kW of power, or roughly 360 horsepower in the old money, and a V6-like 350Nm of torque.

That's some serious twist coming out of the tiny 1.3-litre twin rotor engine, and it illustrates how well the rotary engine takes to forced induction. Mazda Australia calls the concept car the "extreme" RX-8 and has plans to showcase more "extreme" models in future.

The Extreme RX-8 looks the part too, with 19-inch wheels and tyres, a high performance racing brake package, retuned suspension and Mazdaspeed body kit parts for a more aggressive look. Mazda's motor sport manager, Allan Horsley, said: "The RX-8 Motorsport Concept was a must do challenge for us and thanks to the engineering sophistication of the production car it all came together in just a few months.

"The idea behind 'extreme cars' is not just added acceleration and all that goes with that formula. An idea could involve any present Mazda model. We have, for example, discussed an extreme B Series, that would showcase its comfort, refinement and off-road ability," Dickson said.

Mazda has tuned up its high-tech, low displacement rotary engine with a number of new components, beginning with the all-important turbocharger, which in this instance is a water-cooled Garrett GT 30 ball bearing turbo running 7.5 psi of boost.

The relatively low levels of turbo boost were chosen to ensure good throttle response and minimal turbo lag, which helps the car to preserve its "free-revving nature" according to Mazda, and the power is routed to the rear wheels via a 6-speed manual gearbox.

A large air-to-air intercooler has also been adopted for the Extreme RX-8, and together with the turbocharger these modifications are controlled by a re-programmed Power Control Module that help to improve the engine's efficiency in a big way, boosting power by more than 52 per cent over the production RX-8.

In naturally aspirated form, the RX-8 makes a very small amount of torque - just 211Nm.

But with the aid of the turbo this is increased to 350Nm, and again it highlights just how suited to turbocharging the RX-8 twin rotor engine is.

This is further evidenced by the fact that the RX-8 concept's compression ratio and redline are unaffected, allowing the turbo engine to hit 9000rpm without exploding in a violent shower of rotors and high octane fuel.

With the substantially increased power output - and a larger volume of air being forced into the engine - a bigger, less restrictive exhaust system was used, which also provides a deeper soul-stirring exhaust note.

Changes the chassis are fairly substantial too, and with the increase in acceleration, deceleration has been increased as well thanks to a big Alcon six piston racing system comprised of 335mm ventilated and grooved discs, not dissimilar to systems used in V8 Supercar, world rally, NASCAR and Japanese GT racing.

Suspension has been uprated too, aimed at improving the standard car's dynamics and adding to the concept car's visual impact with a drop in ride height by 25mm.

The suspension has also been upgraded to stiffer Eibach springs that help improve grip and reduce body roll through corners.

From a styling point of view, the Australian team of Mazda stylists wanted to make a big impact to reflect the vehicle's newfound performance and as such, the Extreme RX-8 concept gets an aggressive-looking nose section from Mazdaspeed, which includes an integrated spoiler and a larger air intake. An adjustable Mazdaspeed rear wing was also attached.

The 'Velocity Red' mica metallic paint works well with white GT stripes that run along the car's sides, and discreet bonnet flutes help under bonnet cooling. The concept car rides on striking white-painted, 19-inch alloy wheels, shod with 235/35 tyres up front and wider 255/35 tyres on the rear, which helps "deliver the concept's prodigious power and torque to the road" in Mazda speak.

While Mazda has gone to great lengths to let people know that its Australian-engineered Extreme RX-8 is a concept only, one can't help but wonder about the production possibilities.

Such a vehicle could perhaps rekindle the Japanese turbo hey days of the 90s, where Nissan Skylines, Toyota Supras, Mitsubishi 3000 GTs and of course Mazda RX-7s ruled the roost. And with the next generation R35 Skyline GTS set for a 2007 release, a turbo RX-8 would make for a brilliant rival, and may even provoke Toyota into creating a high powered sports car for the 21st century.

The RX-8 Motorsport Concept shares Mazda's Australian International Motor Show stand with the Ibuki concept roadster, which will form the basis of the MX-5 replacement.