I am premixing.

Also, I am only using three lbs of boost.  I was under the impression that this low of boost should not be a problem.  I know there are many other possible causes and will be investigating. 

I may start by putting in a lower boost spring in the waste gate (1.5 lbs) but I am not really thinking this is the issue.  Perhaps timing, as I did play with it quite a bit before I sent my EC2 to Tracy for a check and update.  My higher power tests were quite short as the engine would get hot fast but never to any degree that I would have thought would be a problem.

I have an intercooler, however, without any airflow its usefulness during testing is next to nothing. Also, the intercooler ducting is somewhat minimum at this point.

I thought I would recognize detonation, as Lynn mentioned, but perhaps not.

I also read on the RX-7 site that the rear chamber is the one to usually fail, as mine seems to bare out.