Are you taking into account the shape of the moving air mass in a given cross section of a runner. example - a square or rectangular runner does not have a rectangular column of air flowing thru it. The air flow in the corners is at a reduced rate there for reducing the volume flow (efficiency). Oval or round runners tend to have better flow characteristics in a given cross sectional area. Also bends need to have a larger cross section to maintain the same flow rate. Looking forward to seeing the finished version of the 4bbl manifold.
