So what's the logic behind a certain plenum size and the lenth of the runners? After a lot of reading there seems to be no concencus on this.
A lot of people claim large plenums with short runners, while most actual aftermarket im's have tiny plenums and shortish runners.
Something I've been thinking about is the cross sectional tubes used on a lot of motorcycle headers. It "fools" the engine into thinking the primary is actually longer than it really is, because it's "borrowing" space from the adjacent primary.
Would this concept perhaps work in an IM manifold? I.e. short runners, with smaller diameter cross sectional tubes between 1&2 and 3&4, allowing the cylinder to draw air from 2 intake runners on it's downstroke, while maintaining ideal runner lenth for high rpm?