A patent application describing a new Mazda Renesis rotary engine with direct injection has recently surfaced. Filed this past October in the United States, the application describes the engine in explicit detail, and includes various drawings of the machine as seen from multiple angles.
Mazda showed off what they called their Next Generation Renesis on the Mazda Taiki concept seen at the 2007 Tokyo Motor Show. The company described the engine as having "a longer stroke and larger displacement", that would increase torque from low to high RPMs, and increase "thermal efficiency." The engine was written about as having direct injection, and a housing built of aluminum.
Amongst some of the details outlined in the application are spark plug placement, side air intake, and side exhaust. All of these have been pointed out for their ability to improve "combustion stability" within the engine. Specifically mentioned is the elimination of an overlap between the "intake open timing" and "exhaust open timing", which the company says should also reduce fuel consumption. Not yet determined is the engines maximum number of RPMs, and therefore the size of the rotor's triangular face, as mentioned on page three of the filing.
This, combined with the omission of housing dimensions, suggest that the next Renesis could be a different size than the currently available 1.3-liter model. It is possible that Mazda is trying to stake a claim on multiple engines produced in the manner described. Translation: Mazda may give consumers more than one engine choice on the second generation RX-8, if they begin production of this engine type.
Mazda has used various versions of the Wankel Rotary Engine since the 1960s. After testing an early model, they introduced a 798cc version on the Mazda Cosmo concept shown at the 1963 Tokyo Motor Show. The Japanese automaker began production of a larger model two years later. Other models that have used the rotary engine include the RX series, the R100, and the Luce. The engine is named for self-taught mechanical engineer Felix Wankel. Wankel lived out much of his life in Germany, where he built seals and rotary valves for the Luftwaffe during World War II. He began work on the first rotary engine in the early '50s, completing a prototype in 1957.