Intake Runner Length

[Van Setten, Tim (AZ75)]

Hi All.  
I've been reading your posts here for awhile and learned alot, but now it's
time to ask for help.  We have been fuel injecting our sand rails here in
the southwest now for about 10 years or so.  We are using a speed density
system and also a dual-fuel setup.  We turbo charge our little girlie 2300cc
VW's in a 900 lb car and head to the sand dunes.  The dual fuel is
accomplished by adding a second set of injectors and injecting methanol only
under boost.  This makes these air-cooled engines very happy and stops all
of the pinging problems etc. associated with 15 lbs of boost.  
Now we are playing around with the drive-ability issues.  We want to try
different intake manifold combinations.  
The question is: What size and length should the intake runners be and also
what size should the intake plenum be?  Bruce Bowling's program addresses
the length, but he left out the "diameter" of the runner and I have to
believe that it will make a difference on how big it is.  Also, the
relationship of the plenum, is it sized to the max rpm, or to engine
displacement, or what?  Any comments would be very helpful.
Tim