AUTOS: Mazda Builds Last Rotary Engine - AUTOMOTIVE on SPEED

AUTOS: Mazda Builds Last Rotary Engine

Final RX-8 model rolls off the assembly line in Japan; innovative engine could have a future with hydrogen power.

The last rotary-powered car from Mazda rolled off its production line in Japan on Friday, a Mazda RX-8 Spirit R sold only in the Japanese domestic market.

With no successor confirmed, we may never see a rotary engine in a production car ever again, though those at Mazda don?t want to see it that way.

Part of the reason for its demise is its terrible fuel economy, which is around 40 percent worse than a conventional internal-combustion engine with comparable performance.

The rotary engine is compact and powerful, but not very fuel efficient. (Photo: Mazda) The rotary engine, first launched in the 1967 Mazda Cosmo, did have its pluses. From the tidy 1.3-liter unit found in the RX8 came 232 horsepower, which peaked at a lofty 8,500 rpm with the six-speed manual. And for all the revs, it was still smoother than many piston engines with twice the displacement at half the rpm.

Mazda engineers are toiling away with solutions to make the rotary engine greener, but so far have had little luck. One strategy is the application of SKYACTIV technology, either with direct injection, supercharging or some other conventional fuel-saving technology.

Another, more radical strategy is the use of the rotary strictly as a range-extender for a battery-powered electric car. According to Bloomberg, Mazda is currently testing a rotary burning hydrogen fuel to charge a lithium-ion battery that then drives an electric motor.

Mazda wasn?t the first to proceed down the rotary range-extender development path. Audi first showed the rotary-packing A1 e-tron concept at the 2010 Geneva Motor Show. That allegedly led to talks between Audi and Mazda,
and rumors that Mazda was developing a special-purpose rotary engine for the Audi A1 e-tron. It?s likely that such an engine could also be used to power future Mazda range-extended electric cars.

The Audi connection would bring the rotary full circle. The unique engine design was pioneered by German engineer Felix Wankel shortly after World War II, who at the time was working for Audi NSU Auto Union AG and later licensed the technology to Mazda.

This story originally appeared at Motor Authority.

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