You are not alone in the confusion department!!  From what I've read,

PP's come with a whole set of problems except high rpm horsepower, mainly
because of the overlap.  Excerpt from one article on ports is:  "Peripheral
intake ports (not pictured above) are simply a big hole in each rotor
housing (similar to the exhaust ports), with no side intake ports
whatsoever. Contrary to side port designs, timing is determined by the apex
seal rather than the leading edge of the rotor. This results in massive
intake and exhaust overlap and subsequently very little low-RPM power, but
the direct intake path permits incredible high-RPM power that typically
peaks well over 9,000 RPM. A peripheral port (PP) engine can develop over
300 hp in a non-turbo application, but is not what normal people would
consider "streetable" (but some do!). The water seals are not compromised,
though some of the coolant passages are blocked by the intake passage (but
to a lesser degree than Monster porting) -- the engine life is reduced by
virtue of stress from high-power and high-RPM operation, but not so much by
coolant leakage or hot spots around the intake area."  It would seem that if
one wanted maximum performance across the entire rpm range, the original
ports would be left in operation and smaller peripheral ports added with no
overlap to increase the available mixture.  But, since I've never built one,
I'm just speculating.

Bob

Bob,
Yep! I'm only learning here and trying to play catch-up with chaps that have
been at it for many years experience, like Lynn. It's a bit hard on my poor
old brain.

You hit on a subject which can be a problem - coolant leakage through
thermal cycling. The only solution I can see is one Butch suggested i.e.
through the use of O rings. Although we haven't discussed this in any
detail, I have a suggestion for him to consider, when we get a chance to
discuss it.

George (down under)

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