Wow! - thanks for the link - that post should be pinned it contains so much info - taken ages to read completely and now going away to look at redesigning my effort slightly - going to see if I can build a transition for my 110mm inlet pipe so it enters the chamber as a 150mm X 6.3mm upright rectangle which will reduce the capacity to induce turbulence in the incoming flow as it reduces the incoming orifice width dramatically.
thanks again - away to play with hot PVC
thanks again - away to play with hot PVC