Posted for "Tracy Crook" <lors01@msn.com>:

Mazda had a good reason for making the trailing plug hole smaller.  The
differential chamber pressure between two adjacent rotor chambers is at its
greatest when the apex seal crosses that hole .  Under certain conditions, a
larger hole can cause the 'trailing' chamber to pre-ignite, not a good
thing.

There may be some conditions (in racing applications) where the engine may
make a very small amount of additional power with the trailing plug hole
enlarged,  but in no way can this mod be called an enhancement to
reliability.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com