Mazda's Revolutionary Rotary Returns in a Segment-Busting Sports Car

DETROIT - The North American International Auto Show is host to the North American debut of the mass production design version of Mazda's sleek twin-rotor MAZDA RX-8, the world's only four-door, four-seat sports car and the only one not powered by a piston engine.

Thanks to the compact dimensions of its new RENESIS rotary engine, the MAZDA RX-8, which has virtually the same exterior dimensions as the Porsche 911 Carrera, can accommodate four adults and luggage and deliver world-class sports car performance.

Mazda's rich sports car heritage is evident in the stylish MAZDA RX-8. After four decades of building some of the world's most respected sports cars, Mazda Motor Corporation's engineers set out to create a new sports car formula by blending three seemingly contradictory ingredients: strikingly original sports car styling, a superior blend of sports car handling and performance, ride comfort and practicality for four adults.

One of the key factors in achieving these goals is RENESIS, a new-generation twin-rotor Mazda rotary engine that is smaller and lighter than the company's previous rotary, but produces even more power. Because it has a new side-intake and side-exhaust layout, the engine delivers 250 horsepower at 8,500 rpm and 162 lb-ft of torque at 7,500 rpm without the weight and complexity of a turbo- or supercharger, while achieving improved fuel efficiency and cleaner emissions.

The MAZDA RX-8 features a sophisticated front-midship engine layout as well as a freestyle, four-door configuration without a center pillar, which enables a comfortable interior with space for four adults, belying the attractive sports car styling. The 50:50 front/rear weight distribution and a low yaw-inertia moment give the MAZDA RX-8 outstanding handling. Its superior practicality allows it to appeal to a wider range of customers worldwide.

The form of a genuine sports classic

Mazda has produced many sports cars with exciting styling that stand the test of time, such as the first-generation Cosmo Sport, the RX-7 and the MX-5 Miata. Following this tradition, Mazda designers were determined to give the four-door, four-seat MAZDA RX-8 unprecedented styling.

They began by sculpting a body with a dynamic feeling of motion. Exciting surfaces run from the aggressive front air intake along the body to the trunk lid, and the classic rear-wheel drive sports layout places visual emphasis on the rear tires. Short front and rear overhangs, along with characteristic overfenders, underline the vehicle's look of stability. The styling is a classic statement of beauty in motion, reminiscent of a top athlete, and is the perfect embodiment of Mazda's new design philosophy.

The adoption of the freestyle door system, four doors without a center pillar, means the MAZDA RX-8 features an unprecedented combination of the look and feel of a genuine sports car in a four-door vehicle. The shape of the rear pillars and rear window pay homage to the first-generation Cosmo Sport and RX-7, yet its innovative package provides enough space for four adults.

Low, dynamic front end

The compact design of the MAZDA RX-8's rotary engine allows for aggressive lines extending from the air intake along the low hood and a power bulge in the center of the hood with a rotor as the motif. Along with the short front overhang, the styling features of the MAZDA RX-8 combine to create a dynamic image emphasizing the car's sports car heritage. In addition, the front fender wheel arches stand high and clear of the low hood to visually manifest the MAZDA RX-8's power and provide the driver a clear view of the front corners of the vehicle.

Rear view with emotional and cool styling cues

The rear view is designed to create a vivid impression as the car drives away - an important trademark of any sports car, and is partly achieved by the MAZDA RX-8's short rear overhang. Rear combination lamps receive a mechanical touch through the addition of chrome accents (a rotor-shaped rear fog lamp is located low in the center of the bumper) and the dual exhaust pipes are placed to the left and right. Together, these elements create an impression that is both emotional and contemporary.

Snug, comfortable cabin

In line with the exterior styling, the interior has the emotional impact expected of a true sports car. The design concept is "pleasingly snug," and features newly developed textures and metallic material to produce a bright, modern atmosphere. Once again, Mazda's design philosophy is realized through a combination of the traditional style expected of a sports car with an advanced character suitable for a next-generation four-door sports machine.

Genuine sports cockpit

The cockpit of the MAZDA RX-8 follows Mazda's traditional sports spirit, and gives a feeling of urgent expectancy as soon as you open the door. The interior's basic framework features strong, contoured surfaces flowing from the power bulge on the hood, through the dashboard and the center console to the rear parcel shelf. Along with the center console, designed with a characteristic aluminum frame, the center "backbone" that lies beneath the vehicle is readily apparent.

Vivid, high-quality sports taste

A stylish two-tone color scheme employs black and exterior body color for the seats and trim, while aluminum accents are tastefully used for areas within the driver's reach such as the center console, transmission tunnel and shift lever. In addition, the shift lever, front-seat headrests and side-sill covers feature the unmistakeable triangular shape of the rotary engine's rotors. As a result, the MAZDA RX-8 generates a high-quality, sporty look by integrating the traditional with the modern.

Lightweight sports seats

The lightweight front bucket seats feature a rigid, molded form for the seatbacks, allowing reduction of cushion thickness without sacrificing comfort. This reduces weight and assures ample legroom for passengers in the rear. Thanks to wraparound styling with side and shoulder support, the front seats hold occupants firmly in place even during fast-paced driving. Sun visors also use a mesh texture material to further reduce weight.

Front and rear legroom equal to a sporty sedan

Beneath the unmistakably sports car styling lies a comfortable cabin tailored to fit four adults, helping the MAZDA RX-8 to achieve exceptional functionality. This is made possible through highly efficient packaging centered around the compact, lightweight RENESIS rotary engine, the 106.3-inch wheelbase along with the lightweight sports seats with thinner cushions and seatback. As a result, MAZDA RX-8 achieves the head, shoulder and legroom comparable to other conventional sporty sedans.

Freestyle door system with no center pillars

Even with spacious front and rear seats, a two-door design makes access to the rear seats more difficult and highly inconvenient, while most conventional four-door designs simply do not realize genuine sports car styling. The freestyle door system of MAZDA RX-8 clearly solves this problem. The front doors are hinged at the front in the conventional manner, while the lightweight aluminum rear doors are hinged at the rear. As a result, the system does away with the center pillar, and when both front and rear doors are open, the entry space is free and easily accessible.

Practical, spacious trunk

The MAZDA RX-8 has plentiful storage space for everyday use as well as short trips. Thanks to the freestyle door system, it is easy to stow luggage on the rear seats, and the deep trunk has adequate space to hold as many as two golf bags.

Evolved front-midship layout

The MAZDA RX-8's responsive handling and performance deliver driving pleasure far beyond the normal. One key factor in achieving MAZDA RX-8's unrivaled performance and superb handling is its lightweight, perfectly balanced 50:50 weight distribution, and small yaw-inertia moment and low center of gravity.

The front-midship layout is further enhanced by RENESIS. Naturally aspirated, the RENESIS is smaller and lighter than Mazda's previous turbo rotary engine (13B-REW), and it is only 13.3 inches high, the same height as the transmission. This made it possible to mount the engine approximately 2.4 inches further rearward and some 1.6 inches lower than in the RX-7, which already has the engine's center of gravity behind the front axle.

As a result, MAZDA RX-8 has perfect 50:50 front/rear weight distribution, a small yaw-inertia moment and a low center of gravity identical to the RX-7. In addition, the MAZDA RX-8 realizes nimble, controllable performance and stable high-speed handling thanks to its 106.3- inch wheelbase.

Next-generation rotary engine RENESIS

RENESIS, the key to MAZDA RX-8's front-midship layout, features a side-intake, side-exhaust layout, with the exhaust ports moved to the side housing of the rotor chamber. This allows the size of the ports to be freely set, resulting in an expanded air-intake port area which is 30 percent larger than in conventional rotary engines. This greatly improves intake resistance and contributes to an output of 250 hp at 8,500 rpm and maximum torque of 162 lb-ft at 7,500 rpm without having to rely on a turbo- or supercharger.

In addition, the adoption of dual exhaust ports for each chamber achieves twice the port area of conventional designs and also allows exhaust port timing to be delayed for increased thermal efficiency in the expansion process. Unburned hydrocarbons are retained for combustion in the next cycle, which greatly reduces emissions. A three-stage induction system, featuring shutter valves at the intake ports of each rotor, utilizes the incoming air's dynamic charge effect and improves filling efficiency, while twin electronic throttles precisely and flexibly control the valve operation. Furthermore, a wet-sump lubrication system with oil-pan height just half that of conventional designs also reduces engine size and weight.

High-mount backbone frame

To give the MAZDA RX-8 the rigidity a genuine sports car demands, a strong, high-mount backbone is located in the upper part of the transmission tunnel. This backbone runs from the front bulkhead through the cabin to the rear bulkhead, and functions as the main frame of the chassis-enhancing rigidity and allowing reduction of body-panel thickness and weight. It also contributes to safety in the event of a collision.

Closed-section power plant frame (PPF)

The lightweight closed-section PPF locks the entire powertrain, including the differential gear, into a single, rigid unit. This mechanism enhances direct and linear acceleration feel and crisp shift operation with plenty of sports car driving pleasure.

One-piece, carbon-fiber propeller shaft

Even with a 106.3-inch wheelbase, which is more than a foot longer than the Porsche 911 Carrera's wheelbase, the MAZDA RX-8's front-midship layout drastically shortens the distance from the gearbox to the differential. This allowed engineers to install a one-piece propeller shaft made of carbon fiber, which further reduced weight.

Double-wishbone suspension at front and multi-link beam suspension at rear

A long-arm, double-wishbone suspension at the front and multi-link beam suspension at the rear provide ideal suspension geometry. Long arms and links achieve suspension linearity and roll control, while optimum roll-center height maximizes suspension stroke. Tires remain perpendicular to the road throughout the length of suspension travel for superior grip, even under the tightest cornering. The result is superb handling with no sacrifice in ride comfort. Thanks to the greatly reduced yaw-inertia moment (a result of the front-midship layout), optimum roll-center height and tire camber control, MAZDA RX-8 delivers a sharp response to steering inputs and enhanced controllability.

This chassis and suspension design also allowed the adoption of large-diameter 18-inch aluminum wheels with high-grip 225/45ZR18 tires. Rack-and-pinion power steering gives accurate feedback on road conditions, while an electric power-steering pump delivers precisely the right amount of assist to match driving conditions.

One additional benefit of an electric power-steering pump is improved fuel economy, as electrically driven steering, as opposed to the typical belt-driven system, does not drain power from the engine. Large, 17-inch ventilated discs on all wheels give sure, positive braking in support of safe, sporty driving. Six-point rubber mounts on the rear subframe improve both driving stability and road noise.

Improved performance withstanding side-collisions

Placing the RENESIS engine front midship allows for a sufficiently large crushable zone between the engine and front bumper, and ensures improved impact absorption in head-on and offset frontal collisions. In addition, the MAZDA RX-8 also provides superior performance in withstanding side-impact collisions. The vehicle has a highly rigid body structure for a sports car, in spite of the pillarless, wide-opening design. To achieve a superior body structure, a large number of measures were adopted, including a rigid underbody frame, the high-mount backbone running through the cabin and carefully planned chassis reinforcements. A reinforcement structure forms a virtual center pillar built into the door frames, while top and bottom latches lock the rear door to the body. A safety lock mechanism also allows the rear doors to open only if the front doors are open.

Active-safety measures include large-diameter 17-inch ventilated disc brakes on each wheel, a four-wheel anti-lock braking system, and newly adopted dynamic stability control that senses when the vehicle begins to skid or spin, and counters it by controlling engine torque and applying the brakes as needed.

Tackling environmental problems

Zero overlap between the intake and exhaust ports results in enhanced thermal efficiency for the RENESIS engine, allowing a much leaner air/fuel mixture for fuel efficiency when idling compared to the 13B-REW rotary engine in the RX-7. In addition, thanks to the efficiency inherent in the rotary engine, MAZDA RX-8 operates with a lean mixture even during high-speed, high-load operation.

A high compression ratio and newly developed ultra-fine fuel injectors make virtually perfect combustion possible across the engine's entire speed range.

Rotary engines also have structural qualities that cause them to generate less NOx (nitrogen oxide) than conventional engines. RENESIS' side-exhaust layout retains unburned HC (hydrocarbons) for the next combustion cycle, further lowering emissions. In addition, a newly developed catalytic converter for the rotary engine is teamed with a double-skin exhaust manifold that maintains a high exhaust-gas temperature to improve catalyst activation on engine start, even in cold conditions.

Mazda North American Operations is responsible for the sales and marketing, customer parts and services support of Mazda vehicles in the United States. Headquartered in Irvine, Calif., MNAO has more than 700 dealerships nationwide.

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