Muffler Options For Dry Exhaust
 

I'm currently running 4.5" dry exhaust on my 2003 Spectre 36. It is CMI exhaust and tailpipes on 650 HP naturally aspirated motors from MDG.

What can I do to quiet it down a bit? I don't need to meet any specific dba level, just be the "good" neighbor once in a while. Can I allow some water in right near the tips and not worry about reversion? Are there any clamp on mufflers that would work, but could still be removed when I want?

Thanks!!

I have 830 hp blower motors with dry pipes and I run Gaffrig Mufflers. I made it possible by drilling a 1/8" hole about 1/2" away from the end of the tailpipe. It puts just enough of a mist into the muffler to keep it cool. i've been running it this way for the past 2 years with absolutely no problems. I also noticed a difference in sound by just installing the mufflers and it's much quiter when the mufflers are switched on.

check with your engine builder before drilling the holes but I'd venture to guess you'll be ok! :cool-smiley-011:

I run full dry CMI's on an NA 540, 700+ hp. I use GGB Extreme mufflers with no water at all. They take the bark out of it, but its still pretty loud. The problem is, locating a set of GGB's. They are not around anymore. They have held up fairly well.

Here's a short clip at idle..
http://media.putfile.com/1st-Motor-Running
http://media.putfile.com/1200-rpms

what about the donkey dicks they just curve down in to the water off plane. and when on still turn the sound down. art

They sound like a Bayliner with a small block and an Alpha! :p


blub, blub, blub, blub, blub....:D

I like the CMI Aft-Fires as the give you the ability to switch on and off. The performance loss was only 1 MPH on the top end (100 MPH+) in back to back comparisons with the mufflers installed vs. on un-installed. We run the exhaust system dry to the mufflers, but inject water at the tail pipe exit. I am not sure any muffler would stand up to the heat if there was no water at the muffler to add cooling. Supposedly, the water at the muffler also cuts the sound but I have no personal experience one way or the other.
These mufflers are great inside the marina and in the idle zones, definitely good neighbor....not ultra low DB.

I had a Motion cat with twin 1000s and dry exhaust. Way too loud for the lakes up here. 105DB at idle. What I did was drill two 3/16 holes on the inside of the tailpipe liner to let some water cool the mufflers. The limited amount of water will cut the noise a little. I used CMI sound elmination mufflers with good results. Without water they will turn blue and brown just like dry SS headers on cars.

When drilling the hole(s), drill the hole on the lower end of the pipe so when you shut the engine down the pipe completely drains out.