Our own muffler thread

[2112]

With so many of the new mufflers no longer available, I am wondering who's is now considered the best or one of the best?

I have Zoomers after reading about them in Hotboat. I like the performance and sound. I have not tested them for sound reduction but it is obvious they take the bark out.

What I don't like is the length and weight. They also rust like crazy and need a navel jelly bath after every weekend in the water.

I may go back to Shotguns.

My number one issue is no power loss.

What about you guys?

[Mr Gadgets]

2112,
I am using Borla 4" mufflers with Shotguns at the end. They drag in the water and are pretty quiet. I think I can get down to 88dba, depending on how the test is done. The way the law reads in mich, I see 88dba. The cops dont always do the test properly.
I have CMI headers and had them build tails that dump the water infront of the mufflers. Then the inner pipe extends and I slide on the muffler and clamp it.. They are then supported by my swim platform..
If I can attach photos, I can show you..

Dick

[Airpacker]

We are lucky here in that we have no "noise" law, just a "sound muffling device" law.
I have a set of big corsa transom mount mufflers that have been slightly modified to maintain legality but relieve some back pressure. The nice thing is at off plane speeds, my pipes are almost under water so its not obnoxious to the blow boaters and water cops.

[Offshoredrillin]

gibsons seem to be the ticket being as GGb's arent made any more.

[2112]

2112,
I am using Borla 4" mufflers with Shotguns at the end. They drag in the water and are pretty quiet. I think I can get down to 88dba, depending on how the test is done. The way the law reads in mich, I see 88dba. The cops dont always do the test properly.
I have CMI headers and had them build tails that dump the water infront of the mufflers. Then the inner pipe extends and I slide on the muffler and clamp it.. They are then supported by my swim platform..
If I can attach photos, I can show you..

Dick

My current engines only have 110 degrees of lobe separation so I am always nervous about being under water.

BTW Drew (shotguns) is an old friend, He taught me a lot about rigging and has built many engines for me over the years. I have since graduated to doing most everything myself.

The zoomers function well they are just so huge and rusty.

What about the latest CMIs? I have 2 sets of air actuated CMIs but just don't want the rigging inside my eingine bay.

[FTMBOB]

Here's my 2 cents. I've sold and installed quite a few of the Gibsons. Was doing some dyno testing last year and the customer had a set of the old GGBs with turndowns. We clamped them on and actually gained a couple of HP. That was on a 590 HP engine, running wet. I've had similar results with the Gibsons. I also dyno tested some of the Dana slip in mufflers on a 496 at the prop, with no power loss. I haven't tested any of the others on the dyno.

Bob Lloyd
Full Throttle Marine

[2112]

Here's my 2 cents. I've sold and installed quite a few of the Gibsons. Was doing some dyno testing last year and the customer had a set of the old GGBs with turndowns. We clamped them on and actually gained a couple of HP. That was on a 590 HP engine, running wet. I've had similar results with the Gibsons. I also dyno tested some of the Dana slip in mufflers on a 496 at the prop, with no power loss. I haven't tested any of the others on the dyno.

Bob Lloyd
Full Throttle Marine

How much power loss with the Gibsons? Do you have a picture? Anyone have experience with the CMIs?

[FTMBOB]

The Gibsons transom mounts had no measurable loss at 560 HP.

[ao31]

Lost about 300 rpms on my blown 509's with the Gibsons

[Coolerman]

Here is our setup:

There are 2 cans inside the boat that are 36"x12" where the 2 exhuast pipes enter and the exhuast and water mixes to deaden down alot of the sound. Exiting the can/muffler, it flares from an 8" outlet to 6.5" outlet and then has a 6.5" downturn on the transom. We don't think there is much, if any hp loss because the back pressure is under 1psi.

[Coolerman]

3 more pics

[Boatally Insane]

Here's my 2 cents. I've sold and installed quite a few of the Gibsons. Was doing some dyno testing last year and the customer had a set of the old GGBs with turndowns. We clamped them on and actually gained a couple of HP. That was on a 590 HP engine, running wet.
Bob Lloyd
Full Throttle Marine

....... a building complete with "turndowns"....




Doug

[Mr Gadgets]

2112,
I figured out how to add the pics, so I added one to my post. I ran that setup with a cam with 108* seperation. The CMI's are Tube Tops and dry tails..

[Offshoredrillin]

I spoke for a while with Ron gibson at SEMA, he is now aware of this site and will hopefully become a participant...

[tango]

saxman, NICE work-man-ship ! do ya happen to know where I could find a nice set of those K.E.'s used ?

[Chris]

I have yet to try them but the Hardin Tomahawk muffler looks good. They list it in fixed as well as air-actuated. I really like the idea that it has an internal flapper to stop backwash.

For smaller engines, they have a fixed muffler with an integral turndown- looks like it's aimed at the Merc 525.

[Revd Up]

I've been running the CMI Sound Elimination Mufflers with good results. Not sure of what my decibal reading is but the cops haven't bothered me yet.

[BenPerfected]

We ran back to back tests within 1 hr with and without the CMI 5" air activated mufflers installed on Sport Tubes. They were tested in the open postion with the majority of the water dumping at the top of the tails between the inter & outer pipes at exit. We lose 1 MPH at 100 MPH.
These mufflers do take a significant edge off the bark when closed, but the total reduction in sound is mostly a head fake compared to an less than 88 db goal.