Exhaust

Exhaust collector for a piston engine with multiple cylinders. For a collector of two output valves from the same cylinder, please remove the wall (the one with the knife edge). Intake runners with plenum are straight forward with subdiv, so I would do them on the fly for a specific engine. I tried to misuse crease to simulate that NU in NURBS to get a real circle, but then saw that the order needs to be 4. Fluid is somewhat forgiving, but the valve seat needs higher precision and I would use 40 sectors, like on my piston, for that. I haven't done the calculation, but I feel that the parabola to circle approximation is then better than any production tolerances. Again Sketchfab has problems with the merge of the array mod. Maybe it is a version mismatch of blender. I use wireframe, smooth shading, subdiv to check merge. I should use bevel and grab, too. This model is double walled because solidify fails at the knife. 6 x Array, CurveDeform, Subsurf