With all the talk of velocity stacks i have decided to have my brother fab one up for a school project. Now there problem is i am not sure how to go about doing it. His instructor wants to take a solid peice of aluminum and machine it on the lathe. I was thinking i coud get him to machine a die that could be put on a press and pressed down on a piece of tubing to create the curved leading edge. (i have seen this done for ITB stacks on here) Would this be possible if he heats the metal or would it not be able to conform to that shape? I will try to find pics of the ITB die if i can find them.

Any advise is appreciated.

 

To properly forge the velocity stack you will need a die and a mold. The die would be easy to make on a CNC lathe, but the mold would be a PITA that would have to get done in either a multi-step process or on a 3-axis CNC mill.

You are referring to velocity stacks, and not just bellmouths, right? A velocity stack is a complex venturii shape that must be designed for a target flow rate.