We may not have heard anything of Mazda’s renewed venture into rotary engines since Hiroshima announced its intention to build a new Wankel-powered sports car at the 2015 Tokyo Motor Show. To recap, the company revealed a stunning new concept called the RX-Vision, along with a new SkyActiv-R name for its next-generation rotary engine, but no other details have been released as yet.
However, that doesn’t mean Mazda isn’t hard at work. Case in point: Autoevolution has discovered that the company has filed a patent with the US Patent and Trademark Office, showing a revised version of the novel planetary mill.
So, what did Mazda change, then? Very simple, really – the rotary engine has been “rotated” so that the exhaust port is located in the upper part of the engine, and the intake port in the lower portion. This differs from the company’s existing Wankel engines, which have the opposite configuration.
This small innovation is expected to bring forth manifold benefits. Firstly, the positioning of the intake port at the bottom would mean that the intake manifold has longer to travel and extends downwards. This length would give the engine an extra boost of air, which Mazda calls a “dynamic forced-induction effect caused by an inertia effect,” increasing performance.
Meanwhile, the new placement of the exhaust port would mean that the manifold is now positioned above the engine instead of below it. This would effectively shorten the exhaust passage, reducing resistance and extracting yet more power.
Packaging would also be improved by such a design. Engines such as turbocharged versions of the 13B, used in later versions of the RX-7, featured turbochargers that sat low down next to the engine, which could interfere with other vehicle components such as a crossmember.
With the new exhaust placement, the turbocharger would now be on top; this would enable the engine to sit lower in the chassis and in a smaller space, and also allow space for a larger turbo. The mention of a turbocharger is interesting, as it hints that Mazda might make a return to building turbocharged rotary engines with the SkyActiv-R, after a stint with the naturally-aspirated Renesis mill in the RX-8.
It’s likely that the repositioning of the ports is but one of the innovations Mazda is looking to cram into the SkyActiv-R engine. Expect other significant changes to be introduced in order to improve the rotary engine’s reliability, fuel economy and emissions – all bugbears of existing Wankel mills. The new sports car is expected to debut in 2018, on the 40th anniversary of the RX-7.
GALLERY: Mazda RX-Vision concept at Tokyo 2015
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If I win the lottery jackpot, I will fund for the R&D to develop rotary engines.