Found this on speed talk forum which you might find interesting
SBC wrote:
So what do the intake ports sound like on the bench when you're done porting?
Any distant rumble/thunder?
Or just a steady sssssshhhhhh/white noise?
From my experience most of my good ports that ran well on the track had a very "clean" sound on the bench. Any time there was a "rumble" or other sound it was turbulence and the ports didn't run well on the dyno.
often any noise or "rumble" will be accomponied by the depression manometer jumping.
The above mentioned low ports with NO short turn, .. I do a bunch of 2.L pinto head for road racing.
The is NO short turn, when it's right the port is whisper quiet, .. when it's wrong it sounds like a category 5 twister.
Now in testing, if you have a port like this the first thing I do is use little balls on a welding rod to poke around and find the source.
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Best Regards
Tom Murphy