High Performance Mazda Rotary Engines

Relying on triangular-shaped rotors running along an eccentric shaft for pushing and compressing air/fuel mixture, rotary engines exhibit desirable performance attributes for smaller cars. Advantaged with fewer moving parts than a piston-driven powerplant, rotary engines, sometimes called Wankel engines in homage to its chief inventor Felix Wankel, possess less mechanical resistance during operation. Often running two rotors (three and four rotor engines are less common), performance from a rotary powerplant can be evenly compared to most six-cylinders. As well as aiding power development, the lower part count of rotary engines provides weight savings and a smaller total size which makes it very suitable to smaller engine compartments.

The first automaker to bring rotary engines to market, Mazda has since become a visible champion for this unusual powerplant design with the RX-7 and most recently the RX-8. Starting as an obscure Japanese car builder in 1967, Mazda utilized the potential in using the lightweight rotary engine for their small sports car, the Cosmo 110S. Acquiring licensing to use the newly-discovered rotary engines from Wankel's employer (the now inactive German automaker NSU Motorenwerke AG), Mazda wasn't the only automaker interested in the engine. NSU and Citroen vehicle equipped with rotary engines quickly followed suit of Mazda with public offerings of the new technology. At one point AMC, Mercedes-Benz, and even General Motors also contemplated use of rotary engines for production. Unfortunately, ambition for rotary technology took a downturn as several key drawbacks enveloped the infant engine's development. Firstly, a largely experimental powerplant, early production version of the rotary engine demonstrated terrible reliably as crucial engine tip seals were prone to failure. Secondly, 1970s rotary engine technology ran afoul of an emerging trend of emission and fuel economy standards. By the end of the 1970s, Mazda remained the only auto company to manufacture Wankel-designed engine.

Ultimately deciding to limit rotary engineering to one sports car, Mazda's decision resulted in creating the hottest and longest-living Japanese sports cars to be made available to North America, the Mazda RX-7. Introduced in 1979, over 811,000 vehicles worldwide would wear the RX-7 badge as well as the honor of Mazda's performance flagship. Producing just 100 horsepower initially, rotary engine power improved with the introduction of the 13B engine. The later pairing of the engine with a twin-turbocharger would eventually see a record 276 horsepower moving the two rotors for high-revving excitement. Attributed largely to lightweight rotary engine, the Mazda RX-7 became a darling within the import tuner crowd and even made appearances in the Fast and the Furious movie franchise. With the last RX-7 sold in the United States in 1996, the sports car was formally discontinued in Japan for 2002 due to raising production costs.

Mazda Renesis Engine

Mazda would allow rotary engine technology to resurface in 2003 with the debut of the Mazda RX-8. With the RX-8 body taking the shape of an unique but quirky four-door sports car, the new Renesis rotary engine design marked a monumental step forward in rotary technology. Taking the 13B block used on the RX-7, radical re-engineering saw improvements in fuel economy and emission control while achieving sport-worthy performance. Among the most dramatic changes was the repositioning and enlargement of intake as well as exhaust ports. Combining with a type of exhaust gas recirculation, the RX-8 escapes the emission problems once associated with rotary engines. Producing up to 232 horsepower with the six-speed manual transmission choice, the Renesis engine can carry the RX-8 from 0 to 60 miles per hour in 6.3 seconds. While this RX-8 Renesis engine was left naturally-aspirated unlike the departed RX-7 rotary engine, tuners can readily acquire a bolt-on turbo kit from Greddy for a 50-60 horsepower gain.

While rotary engines are unlikely to evolve beyond a niche product for the interim, Mazda's future planning does larger, more powerful powerplants using the radical technology for a future sports car.