> Does anyone have an optimum configuration for the 13B as a NA engine?  How
> would you convert a 89 6 port to a 4 port engine?  Just grind the end
> housing ports to form one port?  Or is there a 4 port type end housing
that
> could be used like a turbo II end housing.  I am starting with a 88 NA and
> a 89 NA.  Thanks for any help.
>
> Joe Berki
> Limo EZ

After flying both 4 & 6 port engines for hundreds of hours, I would suggest
not doing anything to the ports other than streamlining the square corner of
the upper secondary ports.  There is not a nickle's worth of difference in
power between the two engines when normally aspirated.

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