Paul,
Sorry, the actual engine ports were 18 percent less area than the tubes,
you know the other end of the manifold !
These figures were taken from the info/drawings given with the exercise
to have the lower manifold cast - the one still in progress.
George (down under)

A lot of people open up the ports including Bruce Turrentine that
built Tracy's engine. Ed Anderson also ported his engine. Probably
others but those I know about for sure.

Paul Lamar

Paul,
Yep and they have 18 percent to play with except I'm now wondering if
they have evn more - has anyone looked at the inside port area
facing the Rotar. I sure would like to know if this are is identical to the
outside port area - I sure would like to know if ther is some venturi
Also what do you consider appropriate for interference and parasite drag
for the manifold tubes - I notice you are considering this ! say In
percentage terms ie. educated guess.
Also (in percentage termes) the restriction of the butterfly in the Throttle
Body.
The reason I ask is that by my calculations the throttle body can be 2.75 "
with an 18 Percent reduction  (port area) which = 2.25 " plus the other
factors such as mentioned above plus opening -up the inside port ares.

This approach might give a better understanding to everyone on what
theThrottle Body dimensions are for each configeration.
Also it might explain why some people are getting away with less than
a 3" Throttle Body. Excepting the other reasons you metioned in
specific cases.

Sorry to be a pain, it's just something I've been wondering about,
BTW what size Throttle Body does Mecanair run.
George (down under)

Don't know but here is a picture.

Paul Lamar
 
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