Quote Originally Posted by OldMav View Post
Robo Yes the comments are towards the ebay pic manifold only. For runner entry or divider edges there can be no sharp edges above 15mm radius edges give diminishing returns but under 15mm radius entry edges to the runner create vortex turbulence at those edges which extend into the runner causing choke or less area for fast accelerating air to pass in other words makes the runner entry smaller as air accelerating air. This manifold has no more than 5mm radius edges. For our diesel plenum lid it a accumulator not a plenum as such so the lid top makes no difference for top entry position, But for front entry systems then at least the radius of the entry tube does have a minimal improving effect.
Think I'm reading you, given the preferred radius and---
so adding volume/space by raising the top by 50mm gives the air flowing inwards room to become less turbulent and thus allows for a larger air volume to enter & flow though the runners.
and at the same time keeping inlet manifold size optimal to not suffer pressure drop.