Ken Gratton•31 Oct 2015
NEWS
TOKYO MOTOR SHOW: Mazda rotary's uncertain future
Hiroshima is committed to its signature drivetrain tech – but in what form?Mazda's RX-VISION has set hearts aflutter at the Tokyo motor show this week, but at its own heart is the Wankel rotary engine – an engine long discredited for being a 'gas hog'.
Is there a place for this type of engine in the 21st Century, an era in which consumers question more than ever the impact of the internal-combustion engine on the global environment?
Mazda is giving away little about its strategy for the rotary – but the sports car design study unveiled in Tokyo is the strongest hint yet that the manufacturer is ready to build a rotary-engined sports car that can meet future emissions requirements.
Applying SKYACTIV principles to get a rotary-engined sports car across the line is the first step, but how would those SKYACTIV principles pan out in the context of the unusual Wankel rotary engine concept? Mazda has announced the engine in the RX-VISION as the SKYACTIV-R, with 'R' standing for 'Rotary'. The company has confirmed that the engine displaces 1.6 litres, in line with its most recent R&D work on the rotary. SKYACTIV for the rotary might be as insignificant as Idle-Stop fuel-saving engine management, or it could be something much more advanced. The latter is the more likely.
Kiyoshi Fujiwara, Managing Executive Officer at Mazda, told Australian journalists attending the show that the company could change the shape of the trochoidal rotors in the engine, as one example of a SKYACTIV engineering solution to meet emissions and corporate average fuel economy targets. The housing shape could change too, he said, or the engine might incorporate new materials technology. All would fall within the parameters of SKYACTIV's mission statement.
"That kind of new technology... we can do it," he said.
According to the Mazda R&D boss, the manufacturer has been working on a leaner-running rotary since the 1.6-litre '16X' project of 2007 – predating by some years the end of rotary sports car production when Mazda terminated the RX-8.
"Since that, we have been developing this rotary engine from 16X."
Fujiwara-san wouldn't confirm electric (hybrid-drive) or forced induction for the rotary to meet current and upcoming emission standards, but nor did he rule out either option. He did mention though that he was personally opposed to an energy crutch for the rotary, due to the way it would be perceived by the buying public. This is tied in with the engine's application as a powerplant for a sports car – the singular role Fujiwara-san foresees for the rotary. He was unequivocal that there was no place in the Mazda product range for any rotary-engined car other than a sports car, despite precedents existing.
"Of course, this kind of technology can be utilised for range extending, which was presented two years ago."
The example to which he referred was an experimental Demio (Mazda2) plug-in hybrid with a single-rotor engine and an integrated fuel tank of nine-litre capacity extending the range to a total of about 400km. But 16X/SKYACTIV-R is a 1.6-litre twin-rotor engine that is intended only for a sports car application, he stated.
A production model 'RX-9' based on RX-VISION would likely follow a production model of the Koeru SUV (possibly to be named CX-6), meaning there's a better than even chance SKYACTIV-R will employ technology mooted for phase II of Mazda's SKYACTIV programme. Unique to the rotary, however, SKYACTIV-R is likely to use something more than conventional spark plugs to ignite the fuel/air charge inside the engine. The need to keep spark plugs recessed from the rotary's combustion chamber is one reason the rotary is such a profligate consumer of fossil fuels. Changing the way ignition takes place is bound to be a new fuel-saving mechanism embraced for SKYACTIV-R. But it's not to be confused with HCCI (Homogeneous Charge Compression Ignition), Fujiwara says, although he didn't rule out HCCI for SKYACTIV-R further down the track.
"Of course, HCCI [requires] new technology – especially for the ignition system – but we already found another system... This ignition system can be utilised just for rotary engines, as a first step."
As an aside, Fujiwara-san insinuated that a future production sports car with rotary would not share its platform with the MX-5 convertible.
All the SKYACTIV engineering tactics for the rotary may seem like a lot of effort for not much return from a low-volume seller like a sports car. Mazda's commitment to a new rotary-engined sports car is based around two irresistible forces – consumer demand from global markets like Australia, and a strong sense of loyalty within the company to an engine type that was seen as the saviour of the company in the 1960s.
Mazda Australia MD Martin Benders told motoring.com.au without hesitation that the local push for an 'RX-9' was very strong and based entirely on consumer sentiment.
"For us, that sort of car is a bit overdue in our product portfolio," Benders said, "because the way that the Mazda brand is built, it's sort of got three pillars. One is the design side of things, which I think we do quite well. One's the chassis dynamics, the steering and handling side of things, which I think we do reasonably well. And then there's that technology sort of thing. If you look at the premium brands, technology is a big part of their story – exotic engines, this, that and the other. This is one part of technology that's unique to us. It has an awareness out there amongst people that know about cars.
"I think it is something that would help us with our brand a little..."
It's fairly certain that the RX-VISION will wind up being the basis for a production sports car. That production sports car, we think, will be called the RX-9, and it will be powered by a rotary engine. That rotary engine should be significantly more economical and fuel efficient than the Renesis engine that powered the RX-8. It will likely switch itself off at traffic lights and automatically restart. Priced high enough to sustain the cost of the technology, the sports car will almost certainly recover braking energy to power auxiliary systems. There's a chance it may be offered as a hybrid... and there's even a chance some markets will see the hydrogen-combustion rotary sports car, provided the world keeps building hydrogen fuel replenishment infrastructure, according to one Mazda spokesman.
If rotary power in a production sports car can be truly viable in the 21st Century, Mazda looks to be already a long way down the road of achieving that goal.
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Written byKen Gratton
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