Well yes rifling does make a bullet spin to make it more accurate! Take 2 2-liter Pepsi or coke bottles! Fill them both with water! Let one pour out! Take the other one and shake it in a circle until the water spins like a toilet! And see which one empties faster! The one that's water is spinning empties faster!
My point is if an intake runner, and exhaust header tube, had either rifling in them, or spiralled fins in them, like a tornado! It would cause the air, and fuel together, and the spent exhaust gases! To spiral into the cylinder quicker, and also helping expel exhaust gases quicker! From everything I have ever read about cars! Getting that spiralling air/fuel mixture in the cylinder is what you want! I can't remember the whole reason why! Something to do with getting more in the quench area, and therefore more better combustion or something to that effect!
My problem with the tornado is that is a good idea! But that spinning air going into the intake, spins itself right into the very back of the intake plenum! When most of it hits the back wall of the plenum. I would think the spiralling motion would be scattered! Therefore losing it's spiral motion. That is why I thought screw it! Rifle the damn intake runners, and the exhaust! Quick in, quick out all good! Right!? Maybe good for what!? An extra? let's say!? 5 to 15 hp!? Maybe?
But I am not too sure? One mechanis I work with! Said something about it working, but being too damn fast in and out! And some back pressure is good? Which it is? But I don't quite believe the too fast in and out theory. What do you guys think!
You know what!? One of you has connections! Get your buddy or friend at the machine shop to cut spiral rifling in your junk intake laying around, or your junk header, bolt it up and see what happens!