The 2011 Mazda RX-8 was the last rotary-powered car you could buy in America. Slow sales, poor fuel economy, and tighter emissions standards prevented Mazda from committing to a follow-up. But the fundamental principles of the rotary - compact size and light weight - perfectly fit Mazda's Skyactiv ethos. (For an explanation of how rotaries work, click here.)
In this new engine the intake port sits at the bottom of the engine with the exhaust port on top instead of the other way around. That allows for lower mounting, which improves a car's center of gravity. This rotary is also turbocharged. Putting the turbo up high helps ensure it doesn't get in the way of any body or chassis crossmembers.
The implication of those claims is that somebody is thinking about how to put this engine in a car. There are other benefits as well. The short path from the exhaust port to the turbo ensures minimal turbo lag. It also allows for a close-mounted catalyst on top of the enigne, which will help emissions.
Another innovation in this new engine is a triangle-shaped rotor that covers part of the exhaust port. This allows for different exhaust flow characteristics. The filing claims that that two of the four orientations allow for less airflow resistance in the exhaust port. As in previous Mazda rotaries, there are two spark plugs to manage ignition timing and combustion. But unlike in the 16X concept, Mazda's last public display of such an engine, the new rotary uses port fuel injection.
Keep in mind this is only a patent application. A Mazda spokesperson refused to comment on future product, but commented "As we stated at the Tokyo motor show, Mazda is doing all that it can to bring a rotary to the market." In the meantime, keep your RX-7 prayer candles lit and hope for the return of the rotary before the end of the decade. You can bide your time by reading the entire application here.