I made a pulse-jet out of 3 inch threaded pipe (main tube/combustion chamber) and 2 inch pipe (exhaust tube) total length about 3 feet long with all store bought pieces . The valve is Top Secret though !
Anyway when my Bro and I ran out of propane bottles to run it on I had this brain storm......"Hey, I wonder how Loud it would be on Actylene+Oxygen".....Hmmmm ?
This thing was so powerful it immediately destroyed the valve in a 1 or 2 second burst and was at least as loud as a Top fuel dragster .
I imagine it sounded something like firing off 200 rounds from a gattling gun on an AC130 gunship.
After it self-destructed we frantically shut the garage and the whole operation down anticpating the swift arrival of law enforcement (who fortunately never showed up) !!!