My friends and I are discussing making a custom intake manifold for a buddies ka24de. We're discussing different types of intake types and the best way to build one. We were discussing different plenum designs and the possible gains of velocity stacks inside the manifold itself. Then after that we discussed just running 4 equal lenght pipes to a 4-piece collector into a throttle body. Our weak reasoning was, "What is the point of the plenum?" Me, personally couldn't find anything specific except "it helps."

So my question's are:
Why are plenums necessary?
What is the best design for a plenum. Square, round, round and tapered?

Thanx in advance,
Mike

sob wrong section can a mod move it to tech/misc Thanx.

 

Flow balance. You don't need a plenum if you are going to run a throttle body for each cylinder. Otherwise...