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Looking at a past thread about the different intakes, it mentions the different manifolds 'with a 3/8 inch radiused inlet'. I've asked a few different people that I thought should have known what this means and their reply was, " I'm not sure." Does anybody know what this means?
I dont know for sure myself, but I figured it was for the entrence of the runners on the round end. I thought they were radiused, kind like a counter sink screw.
When I ported the plenum I radiused the inlets into the runners.
If you have a right angle bend where air enters from a plenum into a tube the air will compress and it tries to make the sharp bend; this reduces the effective radius of the tube. Putting a radius on this opening allows for a smooth flow of air with little or no compression as it makes the turn into the tube.
Beyond that the flow should be smooth and even with all openings at right angles, until the air stream gets to the short term radius in the heads.