Muffler inserts for dry exhaust

[LS1Nova]

Just curious if anyone has any experience with the different styles of inserts to kill some noise. I have a Powerplay and the exhaust comes out over the rubrail. It is 1 piece from the manifold back. 4" OD and 3 1/2" ID. So I would need a 3 1/2" muffler insert.

I can't really do a clamp on because they would look like dookie on top of my swim platform.

Thanks,

[Ratickle]

There were some inserts shown in the 1300 hp muffler thread.

[Clustergear]

Back in the late 80's Lake George started with the noise regulation. At that time my Avanti had P1000's tail pipes were dry to the ends. What I did was drill three 3/8" holes at end of pipes so I could put a muffler on tail pipe and it wouldn't get to hot and burn someone. There was a company that made a muffler that you added waffers to adjust noise and it had a manual tee that you gave a 1/4 turn and you had straight pipes. They didn't look to bad and where short. I think l still have one set that I could take a picture of. They didn't have the ulgy clamps on outside of pipes you had to weld two little metal taps inside tail pipe that a tee grabed and the bolt was inside of pipe hidden. The muffler had a taper that slide inside tail pipe so when bolted up it looked like a pipe and muffler were one pice. They were made to run on dry exhaust just had to have some water so they didn't get to hot. My wife bought me a set of CMI mufflers for Christmas for the Powerplay, I hope to get them on next week, my tail pipes are above swin platform like yours will be when you mount swim platform. Let me know if you want picture so you get an idea how your Powerplay would look with old man mufflers. Remember when your out screwing around IF THEY DON'T HEAR YOU - THEY DON'T SEE YA

[LS1Nova]

I'd love to see some pix when you get a chance. Which CMI's did you get? The sound eliminators?

Thanks,
Frank

[Clustergear]

She got me a set of sound eliminators. I had put a set of slip ins to get by for rest of season but they were 94 db's. Thses new ones should knock nosie well below 90 db. Was busy rebuilding drives this weekend.

[LS1Nova]

She got me a set of sound eliminators. I had put a set of slip ins to get by for rest of season but they were 94 db's. Thses new ones should knock nosie well below 90 db. Was busy rebuilding drives this weekend.

Which style slip ins did you use? Do you know what db it was before you added them?

How is you exhaust set up? Mine tailpipes are dry all the way to the back and they have a small hole at the very top to mist water in.

Frank

[Clustergear]

My Powerplay has merc manifold with Imco riser going into silent choice Y than 4 in tails so its basically stock. I did check it but don't remember reading its was well over 100db. I put a set of CP Marine part # 410-284401 4" slip in they took the bark out and were around 94 db both motors running. I don't think they would work in dry pipes. OK when all the noise **** started back years ago in LG after farting around with all kind of slip on and home stuff on my Avanti, I was limited be to want could hang off tail pipes because of swim platform. So I took the tail pipes off the P1000's and sent them to Corsa Perfomance, they cut the pipe about 6" from flange and welded there muffler in that weld pipes back on and put a cross over in. This now made pipes wet at muffler back. It worked very well no lost in speed and crossover increased mid range. the tail pipe when put back in boat looked the same has before except inner pipe was now gone at transom end. As years past it was just over the 90 db law so I cut the pipes shorter and put a set of Gibson muffler tips in and took out cross over, nice and quiet but kill top end. Here is picture of Powerplays exhaust and the Avanti's exhaust has it is now.

[Clustergear]

woops forgot pic

[Clustergear]

I working midnights this week so I have planty of time to think about this stuff while waiting for 6:30 am to get here. If you cut the pipes you have now and stager the cuts so inner pipe is longer than outer pipe so there is no reversion, than put a pice of hose over outer pipe and take inner pipe out of whats left to make tail pipe thru transom. mixing the water into exhaust further up from transom will take alot of the bark out of your exhaust and you probably will not effect performance. and it cheap.

[LS1Nova]

I working midnights this week so I have planty of time to think about this stuff while waiting for 6:30 am to get here. If you cut the pipes you have now and stager the cuts so inner pipe is longer than outer pipe so there is no reversion, than put a pice of hose over outer pipe and take inner pipe out of whats left to make tail pipe thru transom. mixing the water into exhaust further up from transom will take alot of the bark out of your exhaust and you probably will not effect performance. and it cheap.

Thats a pretty good Idea, I was thinking about drilling some holes in the tailpipes also to alow some water in, but I'm going to keep them toward the back so I don't cause any reversion. I really want to do something that I can take in and out. That way I can just yank them out when I feel the urge to be loud

[Clustergear]

If you drill a hole down thru inner pipe where the rear water dump fitting is that will be in front of any inserts and allow water to mix in to exhaust before it hits inserts. start out with small hole and work up till you get enough water mixed in to make mufflers work. Must insert work better (quieter) with exhaust/water mix.

[Clustergear]

Put the CMI's yesterday. Heres pic before and after, this should give you an idea how your boat will look with slip on mufflers and swim platform. Looks better w/o mufflers but the tree huggers always win. So do you have a Nova also ?

[AIR TIME]

Put the CMI's yesterday. Heres pic before and after, this should give you an idea how your boat will look with slip on mufflers and swim platform. Looks better w/o mufflers but the tree huggers always win. So do you have a Nova also ?

I think it looks kool with the longer pipes.

[LS1Nova]

Put the CMI's yesterday. Heres pic before and after, this should give you an idea how your boat will look with slip on mufflers and swim platform. Looks better w/o mufflers but the tree huggers always win. So do you have a Nova also ?

Sorry I didn't get back to you Clustergear. The mufflers look good.

To answer your question, yes I do have a Nova. It's a 64 that I build 7 years ago. Very fun street car! Here's a link for pictures -- CAR PICS

[LS1Nova]

Let us know how it sound when ever you get to fire it up!

Frank