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8V-71 Side Water Discharge

Current Sea

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Can anyone comment on restricting the side water discharge in order to perhaps dampen the exhaust noise on my 47 commander.
Boy those 2 strokes are loud.
 
This is more for moral support than anything else. I don't have your solution but I'm sure there is one. If you have enough engine room space, there is probably a water lift system that will work to cut down on the discharge noise. My guess is though that it will be fairly substantial in size to quiet down those big 568 cu. in. Detroits. Heat rejection without water ingestion is a big deal though and you will really want to find someone to help you engineer the system who knows EXACTLY what he's doing. Those guys are getting harder to find every day.
 
The discharge is prior to mixing with the exhaust. I think it may reduce back pressure to the exhaust system. Not quite sure. If I close this off it will force more water into the exhaust. I was thinking that it might reduce some noise at the back of the boat.
 
Yes, this is my thinking also. Perhaps a gate valve that could reduce water flow and then perform some tests.
Thank you for the reponse.
 
I would NOT recommend that you restrict coolant flow. Marine exhaust manifolds are water cooled to keep your engine room from turning into an oven. Those Detroit diesels are fire breathing dragons and produce exhaust temperatures in excess of 1600*F. Backing up the flow of the coolant could also cause the cylinder head temps to spike due to heat "banking". These heads tend to crack at the fire deck when this happens and then you would really be in a kettle of fish. The ONLY way to quiet down those engines properly is with a resonator chamber capable of allowing the exhaust and water to exit efficiently.
 
I am not considering restricting the closed cooling system. A large amount of sea water exits the boat after the heat exchanger just before it mixes with the exhaust. If I force additional water into the exhaust do you think I would cause some heat issues?
Thank you for your comments.
 
Do not add anymore water to the exhaust by closing off the side discharge. This was installed because the exhaust tube and muffler are a bit to small and will cause back pressure at high speed. The amount of water entering the muffler and exhaust is sufficient for cooling and thats all. Just try to fall in love with them 2 strokes and live with it.
 
stop adding more water in exhaust when you would be closing off the side discharge
i hope this will help you in finding the solution of your problem
you can further ask me for the problem if it remain exist
 
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