Mazda’s patent for new layout may see rotary engine return

Mazda has filed a patent application with the US authorities for a new design of rotary engine which could see the high-revving, lightweight powerplant return to our roads.

The last Mazda rotary, used in the RX-8 sports coupe, died off in 2012, a victim of tightening emissions standards and fuel-consumption expectations which the engine could simply not meet.

Originally designed by engineer Felix Wankel and espoused throughout the 1960s and 1970s by Mazda, NSU and Citroën, eventually the Japanese company became the only holder of the rotary flame.

While we loved the smooth revving, high-power and screaming engine note, the design still had heavy oil consumption and generally lousy economy to deal with.

There was a fillip of hope that the layout could prove ideal for burning hydrogen fuel in a combustion engine. The rotary’s widely-spaced intake and outlet ports are apparently better suited to hydrogen than a conventional overhead valve piston design. However, these aspirations came to nothing.

Revised layout

Now though, Mazda may have cracked it. According to the patent filing, the new SkyActiv Rotary engine has the intake port – for both air and fuel – at the bottom of the engine with the exhaust at the top. That’s the reverse of the traditional positions and Mazda claims that the revised layout has great benefits, not least because it dramatically improves the engine’s efficiency by allowing it to breathe more easily.

There’s another benefit. By putting the intake port at the bottom, Mazda claims to have gotten around the issues of fitting a large turbocharger at the top of the engine, which can cause issues with bonnet height and structural packaging. With the turbo down low, it can be bigger and therefore the engine can be more powerful.

Nothing is being promised yet, and Mazda has a somewhat contrary relationship with the rotary – occasionally declaring it dead, before then about-facing and announcing it’s still being worked on.

Still, with the gorgeous RX-Vision concept being shown and with the 40th birthday of the original RX-7 coupe coming up next year, maybe there is still hope for the old high-rev screamer.