Original name: マツダ RX-8 コンセプト

MAZDA RX-8 MAKES EUROPEAN DEBUT AT GENEVA SHOW

Mazda has taken a giant step towards creating a revolutionary high-performance, four-door sports car with the unveiling of the Mazda RX-8 design and engineering model, which makes its European debut at the Geneva Motor Show.

Based on Mazda's RX-EVOLV concept car introduced at the October 1999 Tokyo Motor Show, RX-8 is much closer to an actual production sports car than its predecessor.

"With its four-door freestyle door system, four-passenger comfort and RENESIS rotary engine, Mazda RX-8 is the next big thing in sports cars," said Mazda President Mark Fields. "I wouldn't be surprised if you see this car – or something very close – on some of Europe’s most scenic, most fun-to-drive highways in the not-so-distant future."

Highlights of the car include:

Mazda's powerful, lightweight and compact RENESIS rotary engine

Central mid-ship layout and 50:50 front/rear weight distribution that dramatically enhance control and handling

Freestyle door system, with front-hinged and rear-hinged doors and no centre pillar to enable fast and easy entry and exit for rear seat passengers

Comfortable seating for four adults

A unique interior design that mixes the traditional with new contemporary material that appears to "wrap around" the passengers

MAZDA RX-8 HAS REVOLUTIONARY DESIGN AND INNOVATIVE FEATURES

By Noboru Katabuchi, Chief Programme Engineer

Throughout our 80-year history, our people have always looked for new and better ways of doing things. Some of our technological breakthroughs include the world's first use of the rotary engine for mass production, the Miller cycle engine, speedsensitive electronic four-wheel steering (4WS), and the creation of the MX-5 roadster, which revolutionised the sports car market worldwide. These efforts have won us the loyalty and support of customers throughout the world.

In the late ’90s, we developed the RX-EVOLV four-door rotary engine concept sports car and unveiled it at the 1999 Tokyo Motor Show. This was the ultimate expression of Mazda’s brand DNA. It was ‘stylish’, ‘insightful’ and ‘spirited’, and it generated plenty of attention. People liked our new idea. So, over the past year, we have worked towards bringing this car closer to production. I’m pleased to announce that we have completed our new-generation four-door rotary engine sports car design and engineering model, which we have called RX-8.

The new RX-8 inherits its basic concept and much of its technology from the RX-EVOLV. It is a ‘design and engineering model’, much closer to what could become the production model. The RENESIS side-exhaust rotary engine, the heart of the RX-8, incorporates important advances over its predecessors. It represents a superb balance between the competing goals of power, fuel economy, low emissions, and responsive feel.

Our biggest challenge with this project was creating a four-door sports car that can seat four adults comfortably while maintaining the look and spirit of a true Mazda rotary engine sports car. What enabled us to realise these goals is the RENESIS engine. One of the most revolutionary features of the RX-8 is the ‘freestyle doors’ with no centre pillars. They make it easy to get in and out of the rear seats while improving convenience and safety.

We also wanted to continue Mazda’s sports car tradition by delivering the dynamic DNA ideal of ‘a feeling of oneness between car and driver’. To realise the factors that make a Mazda sports car special – light weight, front-engine/rear-drive configuration, 50:50 front-rear weight distribution, and low yaw (polar) inertia moment – we selected a lightweight, compact, naturally aspirated rotary engine as the power plant.

We employed a lightweight driveshaft made of carbon composite, and chose lightweight and easily recyclable materials such as aluminium and plastic for the bonnet and wings. In the best Mazda tradition, we undertook the difficult task of making the RX-8 lighter – a job requiring major technological advances – in a confident and resolute manner.

And look at the result! The new RX-8 makes it clear that we are serious about bringing this sports car to market. Mazda's engineering staff – all sports car enthusiasts without exception – are working together as a team to make this project a success. And the final challenge for me, personally, is to find a way to make this dream sports car affordable so customers all over the world will choose it for themselves. The RX-8 is not intended to be a premium sports car. Rather, we want it to be an indispensable part of the user's life like the MX-5, suitable for everyday tasks.

I am proud to be a member of the team responsible for adding this new chapter to Mazda's proud history. It is my sincere wish that you will soon have the opportunity to sit behind the wheel of the new generation four-door rotary engine sports car and experience the exhilaration of the new RENESIS rotary engine.

Noburo Katabuchi has been RX-E programme manager since October 1999. He also worked on the development of the RX-EVOLV from the early planning stages. Mr. Katabuchi joined Mazda in 1973 and holds a degree in mechanical engineering from Waseda University.

DESIGN OF MAZDA RX-8 DRAWS ON MX-5 AND RX-7 HERITAGE

By Yoichi Sato, Chief Designer, Design Promotion Group, and Shigeo Hirata, Designer, Chief Programme Studio

Throughout the years, Mazda designers have created unique sports cars such as the Cosmo Sport, the RX-7, and the MX-5. When we began designing the RX-8, we wanted to create a new sports car that would remain attractive over time, and we wanted to imbue it with Mazda’s design heritage. We wanted to create a car with timeless appeal, like that of the RX-7 and the MX-5.

Since the RX-8 will be powered by a rotary engine, we wanted to adopt a design that no other carmaker could match. The result is a silhouette that unmistakably says ‘sports car’ with enough interior space to seat four adults comfortably. We believe this new four-door sports car is poised to become a Mazda brand icon.

At the 1999 Tokyo Motor Show we debuted the RX-EVOLV, a four-door sports car shown as a ‘concept car’. The RX-EVOLV generated interest among discerning enthusiasts worldwide. Nevertheless, few believed that we were serious about developing a commercial version of this four-door sports coupe.

The RX-8 inherits the basic concept of the RX-EVOLV with design changes that bring it one step closer to mass production. To accomplish this, Mazda design studios in Japan, the United States, and Europe each proposed a number of possible designs and competing ideas. We arrived at the overall shape of the body by showing conceptually our thinking for the future direction of Mazda sports cars.

We located the large 19-inch wheels and tyres at the four corners of the body to provide a sense of stability, and used the extremely short front overhang to create an impression of swiftness and agility.

To reflect the compact layout of the rotary engine, we moved the front pillar more forward than usual and tilted it. This design places most of the appearance of mass toward the back, resulting in a look that suggests that the car's centre of gravity is in the rear.

The front styling features a low bonnet that sets the RX-8 apart from a typical sports saloon. There is also a ‘power bulge’ in the centre of the bonnet representing the rotors of the rotary engine. The five-point grille, the common feature among ‘the Mazda family of vehicles’, functions as the air intake, as in the RX-7 and the MX-5.

Also, the front wings swoop sharply upward above the centre of the bonnet to emphasise the sense of power. When viewed from the driver's seat, the front wings show the positions of the front tyres, making you feel like you can reach out and grab them with your hands. This gives you a feeling of control when driving and manoeuvring the car.

The side profile provides a sense of flow from nose to tail while still emphasizing sharp, strong lines. The ‘double bubble’ roof is a distinguishing feature borrowed from the RX-7. The rear pillars have a cantilevered Z-configuration. The rear window is similar to that of the Cosmo Sport and the RX-7, calling to mind the canopy of a fighter jet.

The rear silhouette, very important in any sports car, maintains the flavour of the MX-5 and early generations of Mazda RX-7. The rear combination lights feature two round brake lamps, one with reversing light and one with turn signal. Combined with the large, bold rear bumper, these elements will leave a strong impression on anyone who sees the RX-8 drive by.

Overall the RX-8 has a compact-looking body, while providing enough interior room to seat four adults comfortably. The use of a compact rotary engine allows for the low bonnet, short overhangs, and overall sports car look while providing ample interior space for four adults.

In designing the interior of the RX-8, we followed the theme of ‘a futuristic blend of the traditional and the modern’. The cockpit aims to be ‘an interior space that is comfortably snug and offers the pleasurable excitement of feeling at one with the car’, the traditional ideal at Mazda. At the same time, we tried to provide a modern, even futuristic flavour.

The instrument panel features large independent speedometer and tachometer gauges based on chronographs. The meter hood is topped by a ‘head up’ display including a shift position indicator. The tachometer needle starts at the 6 o’clock position as is appropriate for a high-rev engine. This design further accentuates the sporty image of the interior. The switches are laid out so they can be accessed easily and quickly when the car is in motion and without the driver having to lean forward. Each switch has its own distinctive feel, so there is no need to take your eyes off the road when operating them. The entire surface of the centre console is covered by an aluminium plate in line with the modern and sporty theme of the interior as a whole.

The lightweight sports mesh seats provide excellent support while contributing to less weight overall. The thin seatbacks free up room and provide extra space to seat four comfortably. Additionally, the seat sides, covered with nubuck canvas, and the shoulder and sides have been shaped forward for a hugging fit. Together, they combine to give a feeling of support and quality.

The rotary engine opened up a whole new world of possibilities for the sports car. Just as the futuristic design of the first generations of the Cosmo Sport and RX-7 attracted admirers when those cars first appeared, the RX-8 will capture the hearts of a new generation of drivers. We are looking forward to the day when you will be able to see the RX-8 on the streets of your town.

Yoichi Sato led the team that designed the interior of the Mazda RX-8. In his 27 years with Mazda, Mr. Sato has worked on the design of the FF GLC, Cosmo AP, 626, X025 concept, earlier and current model RX-7 and the RX-EVOLV concept car.

Shigeo Hirata, 37, is the lead designer of the Mazda RX-8. He joined Mazda in 1987 after graduating from Aichi Prefectural University with a degree in Fine Arts and Music, majoring in Industrial Design. He spent two years in Mazda North American Operations' Advance Design Studio in Irvine, California and two years at Ford Motor Company's Advance Design Studio at Dearborn, Michigan. Mr. Hirata has worked on the design teams of a number of programmes, including the MX-5.

ROTARY ENGINE MAKES IDEAL BODY AND CHASSIS LAYOUT POSSIBLE

By Isao Touda, Assistant Manager, Mazda Basic Design Department

Because it is lightweight, compact and powerful, the RENESIS rotary engine makes it possible to create the RX-8's ideal body and chassis layout. We started developing an innovative body and chassis in 1993, and we used it initially in the RX-01 concept car that we debuted at the 1995 Tokyo Motor Show.

The current RX-7 sports car, which we sell in Japan, makes excellent use of the rotary engine's characteristics as a pure sports car. The RX-8 takes it one step further in a four-door sports car.

RENESIS is a naturally-aspirated engine. It is 30% lighter and more compact than the turbocharged rotary engine (13B-REW) used in the current Mazda RX-7. Its light weight and its positioning in the vehicle helps give the car excellent manoeuvrability and high-end performance.

Even with its supplemental parts, the height of the RENESIS is about the same as an in-line 4-cylinder engine . The engine block itself is only 338mm high – about the same height as the transmission. Since the engine is so compact, we were able to mount the RENESIS close to the centre of the body, resulting in a central front mid-ship layout. Compared with RX-7's front mid-ship layout, the engine in the RX-8 is 60mm closer to the centre of the body.

This central mid-ship layout enables us to achieve the ideal 50:50 weight distribution, dramatically enhancing the handling of the car. So, when you go into a turn at a high rate of speed, you have much more control. Normally, a car would want to spin out under these conditions, but the 50:50 weight distribution provides much more agile handling. It reduces the low inertia moment in turns by up to 15% and helps make the RX-8 fun to drive at normal and at high speeds.

The depth of the RENESIS engine's oil pan is only 40mm, half the depth of the oil pan on the current turbocharged engine that powers the RX-7. This makes it possible to mount the overall powertrain lower to give the car a lower centre of gravity.

By positioning the powertrain lower, we are able to improve rigidity by locating a high mount backbone frame on the upper part of the tunnel. This frame connects the front and rear bulkheads through the inner centre and strengthens body rigidity.

This frame also plays a role as a main body frame to reduce thickness of the body panels, resulting in a 30kg weight reduction. The higher rigidity also enhances safety in front, offset or rear collisions.

Like the MX-5 and RX-7, the RX-8 employs a closed section power plant frame to enhance rigidity. The wheelbase is 2700mm. While most front-engine, rear-wheel drive cars require two propeller shafts with a centre bearing for rigidity, the short distance between transmission and the differential gear makes it possible for only one, made of lightweight carbon composite material. This reduces weight by 3kg.

We adopted double wishbone suspension that delivers excellent grip on the road. The upper and lower arms in both front and rear are much longer compared with RX-7, keeping the tyres gripping the road against changes of roll and camber, providing smooth roll centre and excellent cornering performance. Optimally set up roll centre height and improved camber rigidity enhance control by reducing slower handling reaction. Damper is the mono-tube type that has higher tracking capability. Cornering performance is enhanced by improved lever ratio that prevents excessive roll.

With its 2700mm long wheelbase, the RX-8 provides comfortable interior space for four adults. For rear seat passengers, the centre pillar-less ‘new free style doors’ provide large door openings for better convenience and rear seat accessibility. The RX-8 also has much larger luggage space than a conventional sports car. Rear suspension springs are positioned lower, close to the lower arms, and the rear side frame is located farther out than usual to provide larger, deeper luggage space. The result is more than 300 litres of luggage space that can accommodate two Size 67 Samsonite® suitcases.

The compact RENESIS engine also helps improve collision safety. The central mid-ship layout enables a sufficient crushable zone between engine and bumper, and eases the impact of frontal and offset collision. The RX-8’s bonnet is much lower than that of a sports saloon, and there is more than 100mm space between the upper part of the engine and bonnet. The lower bonnet also improves front visibility.

Safety features attached include smart airbags, head-protection curtain airbags for side collisions, and a non-retreated brake pedal mechanism for frontal and offset collision.

RX-8 will deliver excellent handling, performance, safety, interior space and luggage space in a new generation four-door sports car. The RENESIS engine makes it possible.

Isao Touda, Assistant Manager, Mazda Basic Design, has worked on many projects, including the design of the Mazda RX01 model which made its debut at the 1995 Tokyo Motor Show.

NEW ROTARY ENGINE DELIVERS POWER AND FUEL EFFICIENCY

By Haruo Okimoto, Manager, and Seiji Tajima, Senior Staff Member, RE Engineering Group, Powertrain Development Division

The RX-8 is built to accommodate Mazda's RENESIS rotary engine, an ideal powerplant for sports cars. It is powerful, smooth, lightweight and compact, and it has a low centre of gravity.

‘RENESIS’, derived from the word ‘genesis’, suggests the beginning of a new type of rotary engine. Mazda's work on rotary engines began in 1961 and, six years later, we introduced the Cosmo Sport, powered by the world's first two-rotor engine. Over the years, we made countless improvements. Today, the rotary engine is used in the turbocharged RX-7 that we sell in Japan. To date, Mazda has sold about 1.8 million rotary engine-powered cars.

The RENESIS is an advanced version of the MSP-RE concept rotary engine featured in the RX-01 concept sports car exhibited at the 1995 Tokyo Motor Show. This new-generation rotary engine was employed in the RX-EVOLV four-passenger sports car shown first at the 1999 Tokyo Motor Show. When developing the RENESIS, we aimed to retain power output on a par with the turbocharged 13B-REW, the rotary engine that powers the RX-7, while offering improved fuel economy and reduced emissions.

Unlike previous mass-production rotary engines, which employed side exhaust ports and peripheral intake ports, the naturally aspirated RENESIS has intake and exhaust ports in the side housings. This configuration eliminates overlap between the opening of the intake and exhaust ports, enhancing combustion efficiency. The intake ports are 30% larger and their timing has been changed to make them open sooner than in previous designs. Moreover, the exhaust ports open later, resulting in a longer power (expansion) stroke and providing radically improved heat efficiency.

At the same time, the RENESIS uses a six-port induction (6PI) design, in which each rotor employs three intake ports, and a variable intake timing mechanism. Under this system, dedicated high-speed intake ports begin to operate when the engine operates at high-rev levels. This makes it possible to use the intake's dynamic effect at high and low speeds to maximise compression efficiency.

Unlike the single peripheral port per rotor of previous designs, the RENESIS uses two exhaust ports per rotor. This produces a combined exhaust port opening area nearly twice as large and results in a substantial reduction in exhaust resistance.

The rotors have also been made lighter for better performance at high-rev levels. The rotors used in the RENESIS weigh approximately 14% less than those used in the engine that powers the RX-7, which we sell in Japan. These enhancements provide high output rivalling the power of turbocharged rotary engines with linear power characteristics from the low- to the high-rev range.

The increased heat efficiency resulting from zero overlap between the opening of the intake and exhaust ports makes it possible for the RENESIS to run on a leaner fuel mixture than conventional rotary engines. When idling, the RENESIS consumes 40% less fuel than the current production rotary engine.

Reciprocating piston engines generally use a richer fuel mixture under high-speed and high-load conditions to prevent knocking. In contrast, rotary engines do not require a particularly rich fuel mixture under these conditions due to their special

combustion characteristics. In addition, the RENESIS achieves nearly complete combustion over the entire speed range thanks to its high compression ratio and the use of new fuel injectors designed for improved fuel atomisation. These enhancements allow the RENESIS to run on a leaner fuel mixture than conventional rotary engines from the low to the high-rev range. The result is the power and performance of a sports car engine and reduced fuel consumption.

Due to their configurations, rotary engines produce less oxides of nitrogen (NOx) than reciprocating piston engines, but they also tend to produce large amounts of unburned hydrocarbons. The side exhaust layout used in the RENESIS prevents unburned hydrocarbons of the combustion chamber housing from escaping to the exhaust ports.

Instead, they are carried over and burned in the next combustion cycle, dramatically reducing emissions. In addition, air injection directed into the combustion chamber increases the efficiency of the exhaust reaction significantly over Mazda's existing system during engine startup. Together with the double-skin exhaust manifold, the new layout makes the exhaust much hotter when it reaches the catalytic converter, speeding the converter reaction for clean emissions from the moment the engine is started.

With their low centre of gravity, rotary engines have an advantage over reciprocating piston engines. We have exploited this benefit by using a special oil pan configuration to make the engine's centre of gravity even lower. Called the ‘wet sump’ layout, it uses a baffle (dividing panel) within the oil pan to prevent oil from collecting on one side during cornering. This makes it possible to use a shallower oil pan. Mazda engineers also experimented with ‘dry sump’ designs, but they settled on the new wet sump layout after considering weight, cost and the greater reliability of the simpler system. The new oil pan is only about 40mm deep, about half the depth of conventional designs.

In a rotary engine, oil is supplied directly to the interior walls of the combustion chamber to lubricate the ‘apex’ and ‘corner’ seals. We've kept the paths which supply oil in the RENESIS as small as possible, and we have redesigned the oil supply nozzles to improve their efficiency. With these enhancements, the RENESIS consumes about half as much oil as a conventional rotary engine.

The RENESIS achieves a sophisticated balance between high revs and high output, on the one hand, and fuel economy and low emissions on the other. In addition, we are working to enhance the performance and to realise the high degree of reliability and durability required in a mass-production sports car. We want to achieve high output in the range of 280 horsepower.

Unlike rotary engines equipped with peripheral exhaust ports, the side layout of the RENESIS produces clear, transparent high tones and powerful low tones. We recognise engine sound as a key element in any sports car, and we are working to ensure that the engine produces a satisfying roar as you depress the accelerator.

All of us on the rotary engine engineering team hope you will have the opportunity to experience the feeling that only the RENESIS can deliver. We are dedicated to delivering an engine that will delight sports car enthusiasts worldwide.

Haruo Okimoto joined Mazda in 1975 after graduating from Tokyo University with a master’s degree. He has contributed in the developments of many rotary engine technologies. Among his achievements is the supercharging intake system for the normally aspirated rotary engine, today’s basic technology of rotary engine which significantly improves output power.

Seiji Tajima joined Mazda in 1982 after graduating from Kyusyu University, majoring in mechanical engineering. He has for seven years led the team that developed the side exhaust rotary engine. He is a core member of the great inventor team that has improved engine performance.

SOURCE:  Mazda