mufflers and the man any ideas????????

[flattie]

Well Anyony have any good designs to knock down the decible reading on a blown 468 with over the transom headers? Any help would be appreciated. I dont want to kill the performance

[Squirtin Thunder]

Lots of water !!!

[FASTRAT]

Well Anyony have any good designs to knock down the decible reading on a blown 468 with over the transom headers? Any help would be appreciated. I dont want to kill the performance
when i lived in Cal...we were obligated to run mufflers of some sort...i ran Super Trapps with the removable baffles & met all sound req's...i ran them with all the baffles in (i think there are 6 in each 1)...they passed on any lake that i was on...u can adjust the sound by removeing baffles to make it quieter & tune the headers/mtr to what it likes...for my money...they are the best & easiest to install...just my .02 cents
fastrat

[Heatseeker]

Good luck!
I checked the db level on my blown 468 w/rewarder blower headers and baffles last week. 108-112 at idle!
I don't think there's a muffler around that's going to bring that down enough to pass the test! The best claim I have found on the muffler manufacturer's sites is a 15 db reduction. My cuz installed a set of $400 4" clamp-on GGB mufflers on his hydro for a net reduction of 11 db. Not even close for my application!

[flattie]

I have a set that will get it down to 88 but the boat isnt driveable then It tosses oil out of just about every gasket

[Blown 472]

Get hassled again?

[Heatseeker]

I have a set that will get it down to 88 but the boat isnt driveable then It tosses oil out of just about every gasket
What are you using? I'd like to get mine at least close to the 90db limit. Then again, I certainly don't want to kill the thing and have oil spewing everywhere.

[Jetmugg]

How about turning the exhuast upwards at the end? Would that help to "aim" some of the sound away from the water, to help pass the test?
SteveM.

[Heatseeker]

How about turning the exhuast upwards at the end? Would that help to "aim" some of the sound away from the water, to help pass the test?
SteveM.
J2005 stationary test. This test is from 4 to 5 feet above the water at 3.3 feet from the transom. Test is at low idle speed in neutral. For engines manufactured before January 1, 1993, a noise level of 90 dB(A). For engines manufactured on or after January 1, 1993, a noise
level of 88 dB(A)
Steve, as you can see, the current CA. test is done from above the transom, so turn-ups wouldn't help. Unchained(Mark) had a set-up on his old boat that ran 4" pipes down at about a 45 degree angle off the headers and then turned back about even with the bottom of the boat. This would keep the pipes under water at idle, which would help drastically. The problem is they weren't the prettiest looking things....
It's only a matter of time until headers are effectively illegal! Bastards!!!

[DEL51]

I am one of the sources of flatties troubles.The other is tests that are either unrealistic or downright bullshit.All the ass kissin can't remove the fact that these patrols recieve complaints and have to act upon them.I have to Pass! I am the loudest with GBB clampon mufflers. I am Pro-active an will modify my exhaust.I will install a "Y", Coming off the header collector and run two clamp on mufflers side by side. Next is an up tip, a slight curve from the exhaust up tip bottom side to direct pulses from the transom. I also counted to ten at the site where tests took place. I achieved 81 db at the same distance.

[DEL51]

when i lived in Cal...we were obligated to run mufflers of some sort...i ran Super Trapps with the removable baffles & met all sound req's...i ran them with all the baffles in (i think there are 6 in each 1)...they passed on any lake that i was on...u can adjust the sound by removeing baffles to make it quieter & tune the headers/mtr to what it likes...for my money...they are the best & easiest to install...just my .02 cents
fastrat
The supertraps you mention are no longer available and are a real find.You can piece supertrap plates and have a custom tube made. I'm looking at GBB and Burns Stainless for a combo.

[flattie]

Well I achieved 90 db today with the Bassett race mufflers turned around in the header along with backing off the timing until it would barley run. This was without water. I hope to do some more testing tom night
Flattie

[Kindsvater Flat]

Tractor pull headers.... tall ones.
http://www.holley.com/data/products/pictures/medium2542HKR.jpg

[Unchained]

There were some local guys who ran blown flatbottoms on a lake and they made a 6" or 8" aluminum tube about 3' long that slid over the end of both the headers perpendicular.
It was a large can looking thing, they ran all the engine water through it too and it was real quiet. There were two water drains at the ends of the can and there were many 1" holes across the back that the exhaust came out of.
After a while it get's kind of dirty looking and needed some cleaning.
I think they started out with a piece of aluminum irrigation tube.
It was pretty lightweight and I believe they dyno tested it and had no losses.
Another functional but real different looking device.
Anyone who's more concerned about looks than quiet will never achieve quiet.
There's only so many things that you can ram inside the header tube.
There's only so long that you can ignore the fact that some folks don't want to hear your engine.
I did test out at 90 db at an idle at 25' with my turbo setup but at WOT it is still real loud. I'm ok as long as I don't hammer it right by the launch or someones cottage.
I've got some ideas for a quieter exhaust for a winter project.

[sleekcrafter]

Flattie, I have the same woes here in northern IL. but not as bad as WI. or IA. I have two, Basset mufflers in each collector, and Dynotech cone on each of the collectors. I'm still loud on idle,but it not so bad with water flowing. I had no noticeable power loss as I turn my motor at 6K, I plan on more testing thru out the summer. I am quieter for sure than some other jet boats with original logs, when the water is flowing, but won't pass the idle test yet. I thought about reversing the mufflers as you have, but had not. Keep us posted, Im running out of options too.
Sleek

[Aluminum Squirt]

Hey Unchained, that's a pretty common muffler system on aluminum boats. It's kind of ugly but very effective. I'll try to find a photo or two to post-Aluminum Squirt

[Rampager]

I am starting to worry about this here in Canada too but as of yet we don't have any actual db testing (that I've heard of anyway) The law does not specify a rating, which can be both good and bad of course.
I run Bassett thru transoms and on my boat they ended up 3" or so underwater at idle. its super sweet at idle the boat is as quiet as a car. I'm wodnering tho "if" i came to the states would this pass? I'm uncorked otherwise so once I'm on plane I got nothing. I think it is a little quieter being so low in the wake but I'm not sure as I'm always driving. The tips are basically beside the jetdrive and as a side note I do notice the drive/transom is pretty dirty after a weekend running! (I don't have any pics of my transom yet, I'll try to get some)
Cheers

[crf311]

Has anyone tried the inserts from Car Chemistry Exhaust Inserts . From what i've read they work pretty good on cars with open headers? Maybe worth trying At 55.00 each from summit racing . I my have to.