MSP-RE - Multi Side Port Rotary Engine

Cutaway View
Same image enlarged, though without additional resolution
    Cutaway View Notes
  1. Not obvious in this cutaway is the absence of peripheral exhaust ports, but substitution of side exhaust ports for peripheral exhaust ports is the fundamental difference between production Mazda rotary engines and the not-as-yet regularly produced MSP-RE.
  2. Looking in the intake port area, there appears possibly to be some masking in the image, possibly to prevent leak of proprietary information regarding them. More likely is simply the resolution is inadequate to see that there is additional cutaway in the port area that would otherwise provide self-explanation.


Timing Events
    Timing Events Notes
  1. The timing of a peripheral exhaust port, the line above with the flat top, overlaps the intake events, while there is exactly zero overlap between the side exhaust port event and the intake events. In contrast, on the last 6-port engine produced, the exhaust closed at 48 degrees ATDC, while the intake opened at 32 degrees ATDC, giving a 16 degree overlap period, an amount similar to Otto-Cycle boingers.
  2. The physics of production Mazda rotors and corner seals to date dictate the 32 degree ATDC opening point. Absent a change in corner seal design not evident in the cutaway image, there is an irreconcilable difference between the timing event graph here, and the required 32 degree BTDC side exhaust port closing and 32 degree ATDC intake port opening, a difference of minus 64 degrees of overlap between intake and exhaust events.
  3. Like production Mazda rotaries since 1967, the MSP-RE continues to be distinguished from Otto-Cycle boingers, assuming the correctness of the timing events depicted above, in beginning the intake cycle considerably after the beginning of chamber volume increase (TDC), a factor that contributes to a considerable natural amount of exhaust gas recirculation, though reduced due to the absence of apparent overlap between intake and exhaust events.


Based upon what is available:
  • The cutaway image above
  • The port timing chart above
  • Mazda's HP, torque, and economy claims
One possible explanation is a new corner sealing technique that allows an intake port opening event to begin in the vicinity of or prior to top dead center. This could easily account for the output improvements. A possible way for this could be no sealing change at all, but rather a factory "bridge" port design.

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