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Engine revolution: Mazda’s rotary and its uncertain future

Conventional gas and diesel engines do a commendable job serving car and truck owners’ needs, but futurists insist that electric motors will eventually supplant them as the power source of choice. Some 50 years ago, a similar situation cropped up: Mazda’s ultrasmooth rotary engine had bright hopes of sending pistons the way of the buggy whip. With Mazda celebrating its 100th birthday this year, what better time to toast the brand’s most ambitious technical stride?


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In the early days of IMSA, a team that shall remain unnamed tasked us to improve the sealing of the rotary engine in their racecar. We devised a ceramic Apex seal backed by a high-temp Belleville spring that worked great... on the dyno. Real world testing in the racecar showed a distinct dropoff in power after about two hours of run time. A teardown revealed that while the ceramic seals were intact, they had decided to become very effective lathe tools and had enlarged the housings dimensions to the point where it wasn't as designed. We tried an experimental compressed carbon (very early version of carbon/carbon like current brake rotors) design, but it flaked badly in short order. We had a well-known piston ring manufacturer ready to produce a moly-filled seal, but the team pulled the plug on the program. We kind of pursued it in-house for a bit by designing a ceramic housing liner, but that octopus kept growing more arms and we shelved the whole deal. 

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