Mazda Rotary Engine Returning thanks to Breakthrough

Mazda Rotary Engine Returning thanks to Breakthrough

It would have been easy to write rotary engines off the speculative books at Mazda — poor milage and questionable long-term reliability made traditional piston engines seem favorable to many. 

Yet against the odds, the Japanese automaker seems to have found a formula to keep the smooth-spinning screamer alive in its lineup.

Mitsuo Hitomi, general manager of powertrain development at Mazda recently said that the company plans to complete development of such an engine that will also meet future fuel-economy and emissions standards.

“We think we’ve found a way to improve the rotary’s fuel economy to be truly equal to that of conventional piston engines and, if so, we believe we can reintroduce the rotary to the market,” Hitomi recently told Ward’s Auto.

Much of the new technological breakthrough came in changing the shape of the troichoid housing so that the seals remained flush to the housing. Better sealing means better fuel economy and overall performance. Since the early days of rotary engines, its seals and its “sealability” have always been an issue, dating back to the mid-1960s. “Even with our current 1.3L Renesis rotary, gaps can develop between the apex seal and troichoid housing in light-load operation when imbalances in centrifugal force and gas pressure occur,” Himoti said.

The next engineering enhancement for the new rotary engine will be a focus on ignition. Unfortunately the engineer couldn’t explain on how the Japanese automaker plans on addressing that problem.

Regardless of the improvements made in the next-generation rotary engine, we expect to see it being used for extended-range electric vehicles and Mazda’s Skyactiv technology to be incorporated.

[Source: Wards Auto]

  • steve

    will DI work on the rotary engine, that would be awesome, and a SC for low end kick.

  • Simon

    Hi Steve – There are direct injection common rail diesel rotary engines in development in Europe. They are spark ignition and have the ability to run multiple fuels and much wider fuel tolerances than piston engines. Power to weight ratio is high and smooth running. I have seen a 2 rotor turbo (700cc) engine producing 135Hp at 8,000 rpm. A 4 rotor turbo (2000cc) has been tested at over 400Hp at 8000rpm – on diesel… 6 and 8 rotor versions are rumoured. Primary market application is power generation.

    They are not yet publicly available or released, but they are coming. I know as I am involved in the project.

    Mazda rotaries are great engines but the Renesis was crying out for fuel system development to combat the limitations. Think about port injected petrol, where is the fuel mixture? Also, petrol will affect the oil film in the inlet side of the chamber and reduce lubricity so potential to increase Apex wear.

    Direct injection diesel works well for longevity as it is a high lubricity fuel and with modern stratified charge you can position a rich mixture near the spark plug for a leaner and more efficient burn.

    Improved radial ports and no throttle butterfly removes pumping losses in the diesel cycle.

    Keep your eyes peeled in 18 months time in the marine field, these will be supercharged…


    wankel engines are the future 1 847 421 3592