Mazda Could Revive the Rotary

Mazda recently made an announcement about its future with regards to power units. It was an announcement that helped the industry know what their plans were and how they were going to achieve them.

Mazda has been one of the last manufacturers to say what they were going to do because they were seen as the last bastion of the internal combustion engine with their SkyActiv-G and SkyActiv-X engines that eked out greater efficiencies. Unsurprisingly, the announcement was about electric power and range extender power units.

To start with, Mazda have now stated that they will have some fully electric cars by 2030 – around the time that many cities have said they will ban petrol and (hopefully only carbon based) diesels. They have said that there will be an electric power option on all their vehicles. Initially they will develop one fully electric model and one range extender.

This is the one that took everyone by surprise – the range extender will basically be an electric car with a small range extending motor to recharge the batteries that supply the power to the wheels. That range extending motor is going to be based on their rotary technology, albeit a much smaller capacity version. Mazda say that the rotary engine is perfect for this function because it is much more compact than a piston engine, provides enough power and is quiet. They have also made it work with Liquid Petroleum Gas for even more efficiency.

To help speed up development of the technologies, Mazda has formed a joint venture with Denso, a component manufacturer, and Toyota. The new company is called the EV Common Architecture Spirit Company and the commercialised products coming out of the joint venture will be available after 2020. Prior to that though, Mazda will release a hybrid car next year to bridge the gap.

Mazda officially dropped the rotary engine when the RX8 was discontinued in 2012 although they did produce a prototype Mazda 2 with a 330cc rotary engine as a range extender power unit. Making the unit much smaller and not having to run through a gearbox means that the motor could be repositioned in the vehicle for better weight distribution or passenger comfort – I suppose that would depend on the amount of heat generated and how often it was used.

One idea that Mazda could re-visit, is the work that Rolls-Royce undertook in the early 1970s when they made a twin rotor engine run on diesel. Rolls-Royce used a large rotor to compress the fuel mix into a smaller rotor for combustion, in effect, the larger rotor acted as a supercharger for the smaller one. Admittedly the larger rotor had an effective displacement of 3.2 litres and the smaller one had an effective displacement of 1.2 litres, so if Mazda could shrink the rotor sizes down and make it work, then they could use carbon and bio-diesels as a fuel source.

I still feel that there is life in bio-diesels where the source of the fuel is a waste product from another process. Having a rotary engine that used a clean fuel source to generate the electrical current would make these cars even cleaner (assuming the refining process is efficient).