Any list of “dearly departed” road cars cannot be complete without mention of the storied Mazda RX-7. For many enthusiasts, it was the pinnacle of Japanese sports car engineering, and much of that boiled down to its very special (and high-revving) Wankel rotary engine.
Mazda famously ended production of the Wankel in 2012, not particularly because it wanted to, but because it had to. The last-gen “Renesis” unit failed to pass muster in European emissions testing.
Since then however, Mazda has announced its intentions to revive the whizzy Wankel engines, and even went so far as to put one under its recent RX-Vision concept car. It goes by the name of “Skyactiv-R” now, and this Mazda patent application may be the world’s first detailed look at the new mill.
Filed on August 12, 2015 with the U.S. Patent Office, the new rotary engine design features a major change from Mazda’s conventional formula. Now the engine’s exhaust ports have been shifted 180-degrees toward the top of the engine, while the intake ports have been shifted towards the bottom.
As the patent explains, the benefits of such a shift would allow for a shorter exhaust outlet and for a turbocharger to be mounted much closer along that outlet, in fact, above and to the side of the engine (as seen in the “Fig. 2” side-view, above). The design would effectively increase turbo spooling response and as a result allow Mazda to mount a slightly larger turbo for increased power.
The patent also notes this new design would allow for better packaging within a vehicle engine bay (avoiding structural crossmembers beneath the engine), and a lower mounting location, which provides a lower center of gravity.
Of interesting note, Mazda has designed the exhaust outlet with two catalysts, one almost directly behind the turbocharger and the other further back beneath the car’s body (points 35 and 36 in the above bird’s eye diagram). This setup is a clear attempt to cut down on what has historically been one of the Wankel engine’s biggest drawbacks—poor emissions.
So does this all lend credence to the arrival of a new Mazda RX-7 or RX-8 in the immediate future? Potentially. Mazda clearly believes in the Wankel engine’s performance, otherwise the project wouldn’t have been carried on for so long. That said, while he groundwork has been laid, only time will tell if Mazda engineers can bring such a car to market.
It is worth noting however that the Mazda RX-7 will celebrate its 40th anniversary in 2018. Tick tock…
Photo Credit: Mazda, USPTO