Tracy said:

Interesting, yes, but I doubt it would be encouraging.  I fully acknowledge that this is undoubtedly a relatively risky venture.

Yes, I suppose you are right.  My initial thought was that it might not be a big difference; suggesting that the problem is not the engine, but the balance of the installation.  But the installation of a certified engine is much more ‘standard’, and there are FWF packages available.   But even for the same type of ‘alternative’ engine it can be hard to find any standardization.  

In choosing to do this, you are betting your life that you have the necessary skills and knowledge to develop a one of a kind aircraft propulsion system - not a trivial task, and a far greater challenge than using time proven systems based on conventional aircraft engines.

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If you do, there is no better alternative than the Mazda rotary.

Right again.  Before making an engine selection for my Velocity I spent an extensive period of time on evaluation and comparison of every possible engine option; which, of course, included the certified engines.  It finally narrowed down to the ‘standard’ IO360, or a 3-rotor rotary.  After a period of vacillation, I finally knew that I could not be satisfied with the old technology Lycoming on a state-of-the-art airframe.  I knew that making a gain in performance, smoothness, ease of operation, and, yes, reliability; would be a major challenge.  And I believed I had “necessary skills and knowledge” to meet that challenge.

There are many one-of-a-kind aspects to the installation, but at this point it appears that the gains that I was after are/will be achieved – except for the reliability.  That has yet to be proven; and is by far the most difficult to achieve. 

Al