There are only two runners instead of four so naturally the speed will have to be double assuming the same size runners. If in the case of side port, the intake runner i.d.s are reduced, the skin friction will be greatly increased. Face it, side ports are a drag. There is no way velocities in a four runner intake can ever approach those of a two runner p port. IMHO, Jerry

In order to deliver the same CFM at the same depression, the single runner need not equal the cross section of two runners. To say it another way: A single runner of the same cross section as the two it replaces, will deliver the same CFM at a lower velocity. The larger the tube, the lower the velocity. Lower velocity = lower drag.

 

Drag increases at about the cube of velocity. So the single tube is far more efficient than the two tubes with half the cross section. Plus no losses caused by the turns.

 

Lynn E. Hanover