Rotary engines aren’t perfect. They’re known to burn oil, blow seals, make very little torque and above all, not do so hot on EPA fuel economy drive cycles. Despite all that, there’s something about the high-revving swirly hamentaschen that has our hearts, and now Mazda’s filed a patent that could make them feasible again.
Mazda showed us the RX-Vision last year, but remained tight-lipped on its engine tech. Admitting only that it had a “SkyActive-R” rotary engine under the hood, the Japanese automaker said nothing of displacement, aspiration method or other engineer-y goodness.
But Auto Evolution caught wind of Mazda’s recent rotary engine patent filing, and it looks like the automaker’s got some tricks of its sleeves to perhaps get a Wankel back under the hood of a production car. Hopefully.
The patent filing essentially describes a rotary engine that’s mounted 180 degrees off from a conventional engine (rotated about the output shaft axis). This new mounting strategy puts the intake port at the bottom of the engine, and the exhaust port at the top, opposite to what you’d see in a conventional Wankel engine
Mazda says the major benefits include improved underhood package-ability and better engine performance.
The patent asserts that conventional Wankel engines with high-mounted intake ports tend to have short intake passages pulling air from above the engine. The automaker’s new proposed low intake port can offer improved efficiency, because a lower intake port with long intake passages drawing from below the engine can use incoming air’s inertia to produce a “dynamic forced-induction effect,” ultimately resulting in better volumetric efficiency and therefore better engine performance.
Improved performance is always, always good. In case you were confused.
The high-positioned exhaust port allows for an exhaust passage that runs above the engine, and is shorter than a conventional exhaust passage, yielding lower exhaust backpressure.
On the packaging front, Mazda says that putting the intake passage, which is fairly simple to package, below the engine allows the engine to drop in the vertical direction compared to a conventional Wankel, since a conventional engine tends to be limited by turbocharger-vehicle crossmember interference. Mazda says that lowering the engine means fitting a big, whopping turbo could become a lot easier (emphasis mine):
As a result, the space above the rotary piston engine can easily be secured and, for example, a large-sized exhaust turbocharger can be accommodated inside the engine room by being disposed above the rotary piston engine body.”
Large-sized turbocharger on a Wankel? Please don’t be teasing us, Mazda.