I originally posted this on toymods and there sure is some debate over the result, here is the original thread:
so for the interest sake I am posting this here as well:
I have been thinking about doing an unsual modification to my 20v intake. Even since I started doing some matchporting on my first spare 20v head years ago I thought it was odd that there was a decent step from where the intake manifold meets the head. Sure I did some matchporting to have a nicer radius but its still roughly a 15 degree bend in the manifold port to the intake port. I have been told anything more than a 7 degree change in direction without a radius will cause flow seperation of the laminar layer causing eddies in region just after the angle change, effectively reducing the cross sectional area and screwing with the harmonics. But I must stress aerodynamics isnt something I understand very well so I could of just said something stupid.
I hate to quote second hand info but I have heard that a worklshop in Vic somewhere did some testing on a flowbench and gained a 10% flow gain by making the inlet path in a straight line. Assuming this is true I still have no idea what this means for real world use.
I have started making an angled spacer to do the same on my engine and I am wondering if its an effert of futility. I will have it so the original manifold bolts up in such a way that I will be able to open a throttle and look down inside to see my three inlet valves. It will be made from one main block of aluminium and smaller block for a clamp (dont ask).
Anyone have any thoughts if there might be a difference in the real world by doing such a change.
Any further questions and theories?
Thanks to Shelldrake for this idea and info.