Noise reduction with dry headers
03-27-2018 | 01:44 PM
#1
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Noise reduction with dry headers
I have a 29 Fountain with a strong 540 with CMI Sport Tube headers and 4.5 tails. I have a Howard cam with a 114 LSA 242 254 duration at .50 degree, Brodix BB-2 aluminum heads, 10.5 compression, with a Holley EFI. I replaced the Bravo drive with an IMCO SCX upper with a SC -2 lower. I plan on running a 5 blade prop. About the only thing I need is something that will temper the sound of a BBC with straight pipes. I have found two possible options, Harden Marine HCX Series Offshore Mufflers and GGB inserts. Both mufflers are inserts in CMI Tails. Has anyone had any experience with either of these options? I need to get one of these or something else so I can get my boat in the water this spring.Thanks for any feedback.
03-27-2018 | 03:18 PM
#2
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Joined: Jul 2004
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From: chicago
Ive never used those, but I have used these. A small hole drilled into the end of the tailpipe will allow just enough water thru to keep them cool. They are effective at reducing the noise when closed.
1220 GAFFRIG SUPERFLO SERIES MUFFLER 4.5I.D. TAIL PIPE (1-PAIR) INCLUDES PUMP KIT
1220 GAFFRIG SUPERFLO SERIES MUFFLER 4.5I.D. TAIL PIPE (1-PAIR) INCLUDES PUMP KIT
03-28-2018 | 05:51 AM
#4
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From: Dayton, OH/Burnside KY
I have dry exhaust as well and the only thing I have found that will work without cooking are the GGB's. Those Gaffrigs will most likely eat themselves up from the heat and turn brown.
Last edited by corey331; 03-28-2018 at 05:54 AM.
03-28-2018 | 06:44 AM
#5
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From: chicago
Its nice being able to close them around the docks, or launch ramp, and open them when up and running.
03-28-2018 | 07:46 AM
#6
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From: Warwick, MD USA
I've also had no issues running GGB inserts in my dry CMI tailpipe where the water exits at the rear edge of the pipe adjacent to the inserts.
03-28-2018 | 11:24 PM
#9
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From: SF Bay Area
I’m always pumping the GGB inserts here simply because they are so effective with near no drawbacks. Someone at one time even made a case for them actually help fight reversion but I have no way of substantiating that. I put the 5.5x4” units in my wet tails and it *felt* like it cut the sound in half.
04-02-2018 | 10:26 AM
#10
Frank's Marine Service
Joined: Sep 2002
Posts: 11,959
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From: Elkton, MD
Small weep hole at the top of the pipe and then run bolt the mufflers on. I did this for about a decade on my dry exhaust (both headers and manifold setups).
Got divorced and pulled the mufflers off 4 years ago a week after separation....lol Buh bye mufflers! Possibly sell them as they're collecting dust in my loft.
Got divorced and pulled the mufflers off 4 years ago a week after separation....lol Buh bye mufflers! Possibly sell them as they're collecting dust in my loft.
