Mazda Races Ahead With Revolutionary Mazda RX-8 - The Renesis Twin Rotor Engine | Part Two

While there is plenty of space for four adults, the new Mazda RX-8 achieves its sports car character via a traditional front-mounted engine/rear-wheel drive layout. The engine is mounted 60mm further back and 40mm lower than in the two-seater Mazda RX-7, giving the Mazda RX-8 an optimal 50:50 front-to-rear weight distribution for perfectly balanced handling and a chassis design that reflects the engineers’ quest for sportiness without compromise.

The car is powered by the Renesis twin-rotor engine, which is the first in a new generation of rotary engines. Although normally-aspirated, it is smaller and lighter than its predecessors, and is capable of generating approximately the same power output as the earlier bi-turbo unit – as well as delivering improved fuel consumption and lower emissions.

The compact, water-cooled unit – with two rotary pistons and combustion chambers each with 654 cc capacity – produces 240 PS at 8200 rpm. The engine’s maximum torque of 220 Nm is achieved at 7500 rpm, but 90% of torque is available from just 3250 rpm.

Including all its ancillary systems, the Renesis is approximately the same size as a conventional four-cylinder in-line engine, but it has only three moving parts compared to at least 40 in a four-in-line. The engine block is only 338 mm high, the same as the transmission, and a special shallow draft, wet-sump design allows the engine to be mounted lower in the chassis.

The Mazda RX-8’s compact rotary engine, long wheelbase of 2700 mm and space-saving sports seats create generous amounts of interior space. Head, shoulder and knee room are comparable to that of conventional sports saloons. The new chassis sits on 18-inch wheels with 225/45 ZR tyres, while the double-wishbone suspension system delivers excellent ride and handling characteristics. The High-Power model is equipped with a six-speed manual transmission, ABS and DSC stability control.

The Mazda RX-8 employs an engine housing with a closed cross-section, which contributes to chassis stiffness, as does the deep aluminium-trimmed transmission tunnel which extends the full length of the cabin. The bodyshell has 70% greater torsional stiffness than the Mazda RX-7. Because the engine and gearbox are mounted so far back in the chassis, the distance to the rear differential is reduced and a single carbon composite drive-shaft is used, saving more weight.

For the interior, Mazda designers chose a mixture of modern and traditional. The dominant trim colours are black with panels in contrasting body-colour fabric and leather, with a pale roof lining. The speedometer and tachometer are of classic design and the bright alloy pedals are ‘drilled’ for a racy appearance. The tachometer has its zero position at six o’clock, appropriate to a car that revs to high rpm. All controls are within easy reach of the driver and standard safety features on the Mazda RX-8 include intelligent front and side airbags.

Mazda RX-8/Outline Specification
Engine (High Power model)  
Displacement 1308cc twin-chamber rotary
Maximum output 240 PS at 8200 rpm
Maximum torque 220 Nm at 7500 rpm
Transmission (High Power model)  
Gearbox 6 speed manual
Prop-shaft carbon composite
Differential rear-mounted limited-slip
Length 4435 mm
Wheelbase 2700mm
Width 1770 mm
Weight 1330 kg
Height 1340 mm
Published 15 January 2003 Melanie Carter

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