Quietest thru transom exhaust setup
08-06-2014, 03:38 PM
#11
Matt, from what you have said I think the turn downs (donkey dicks, as SB calls them) would be your best solution. Would sound similar to thru-prop, without the fears of reversion or performance penalty. Easy to remove if you want to make some noise too.
08-07-2014, 08:26 AM
#12
Matt, sounds like you might want to take a look at the GGB muffled tips, based on what the original poster said in the last post of this thread:
http://www.offshoreonly.com/forums/g...options-7.html
http://www.offshoreonly.com/forums/g...options-7.html
08-07-2014, 02:24 PM
#13
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08-07-2014, 03:45 PM
#14
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Your best bet is a set of GGB mufflers and turn down tips. You can cut the length to exit right at the water line. I run this setup on my Nordic with 800 naturally aspirated HP (pretty big cam)and it works great. Right at 82 db at idle. Only problem you run into is when launching on a steep ramp the tips go under water causing extra back pressure. Makes it hard to start sometimes if they get deep in the water.
Bob Lloyd
Bob Lloyd
08-08-2014, 07:26 AM
#17
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I have a set of corsa muffler tips. the hole in the back of them is just over 1 inch diameter. I dunno how much "performance" one can get from that!! fortunately, they were bought cuz I can't stand the thought of having a thru-prop only boat. my 24.5 crownie is a driver I bought to make spousal unit happy.
08-08-2014, 03:49 PM
#18
I have a similar issue as the OP. Warmed over stroker with straight 4" thru hull. Wanted to tone it down for the family, not so much LE. Bought one type of muffler insert, they did quiet things down a bit but choked about 500 rpm on the big end (5000 rpm vice 5500ish). Recently installed the 5 ring GGB competition inserts and they work well. Bark is toned down once the water starts flowing. Idle dB was 82. Best part is I was able to spin the motor to nearly 5700 rpm with these installed.
I'd need full turn downs to get things any quieter without restriction.
I'd need full turn downs to get things any quieter without restriction.
08-08-2014, 08:07 PM
#19
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That's a big cam for a tubing and ski rig. Being that it's a roller, it should have fairly aggressive ramps. What's the cam card say for EVO BTDC? You may consider advancing the crap out of the cam. Depending on the ramp profile, it may allow you to keep your silent choice and it will also move the power down to a lower RPM which would be beneficial for popping up skiers and dragging tubes around.
08-09-2014, 07:04 AM
#20
It is sufficient now for pulling up skiers and tubers, I can only imagine with the extra 35 cubic inches it will be better. The only reason I went with this much motor is my current 350 is wounded and it would cost me more to build a basic 383 than this motor did, and it has way better stuff in it. I think I will run it how it is and see how it runs. It does have a quick access timing cover so advancing the cam won't be a big deal in the boat if I decide to change it.
