Installing Slip in Exhaust Silencers

[solorex]

4 hours ago, MadMan said:

I would think those manifolds would fit every small block Chevy since 1955.

The exhaust flow in those manifolds are like tri-y headers form the '60s.  A reason for the tri-y design is to split up the exhaust flow between cylinders 5 & 7 since they are back to back in the firing order.  Indmar didn't do this on their design, 5 & 7 are on the same Y.

So this is a bad thing on the Indmars?  If I am going to shell out $1000 per side, want to make sure I am getting some benefit!   Actually.. sorry our pathetic CDN dollar these days makes it even more expensive... have to add 30%

Edited July 5, 2017 by solorex

[Michigan boarder]

On 7/2/2017 at 3:43 PM, Luckylindy said:

https://vault.myvzw.com/webcs/app/share/invite/Bl9dznIclE

https://vault.myvzw.com/webcs/app/share/invite/YIYlQ7t85l

The boot is a 4" clay to 4" pvc. The elbow is a 4" to 3" street elbow after slipping the tip into the boot a added a few screws through the boot before the clamp went on the help hold it in, not sure if it was necessary, but it made me feel better. I considered using a 4" both end elbow but thought the 3" tip looked less bulky and the hole in the existing tip is only 3" so I knew it wouldn't choke the flow. The way these are now there is a bit of spray off them. I had a set before that i trimmed the last 2" or so step off of to get rid of the spray, but it made it louder so I replaced them and just deal with it , it's really not that bad.  

That is pretty amazing and really inexpensive.  Good thinking!

[MadMan]

2 hours ago, solorex said:

So this is a bad thing on the Indmars?  If I am going to shell out $1000 per side, want to make sure I am getting some benefit!   Actually.. sorry our pathetic CDN dollar these days makes it even more expensive... have to add 30%

I would say it depends on what you do with your boat.  They will likely add some power, but only at upper RPM, maybe around 5k.  At lower RPM, around 3k, the improvement would be negligible.  So, if you're a bare-footer, they would help.  Not so much for wakeboarding.

They do look like they would flow more than the iron manifolds, it's just that Indmar might have left some power on the table.

[drh]

To update this I installed the stainless steel silencers from Eddie Marine over the weekend and there's a significant difference in sound. It's more of a refined rumble than a raw bark and its definitely quieter although it wouldn't hurt to quiet it a bit more for the riders in the rear bench (from the driver's seat its quiet enough in my opinion) so I'm planning on trying the turn downs that @Luckylindy fabbed up. It's now bearable in the rear and you can carry on a convo without shouting but for a few bucks I figured it's worth trying.

@Luckylindy Thanks for the pics...great idea. Are those elbows black PVC or ABS plastic? Looking at Home Depot it appears all the PVC is white and ABS is black. 

[Spicoli]

Michigan Boarder, I like the set up, where do you get the Chrome tips from ? w/ wo flap

[Luckylindy]

13 hours ago, drh said:

To update this I installed the stainless steel silencers from Eddie Marine over the weekend and there's a significant difference in sound. It's more of a refined rumble than a raw bark and its definitely quieter although it wouldn't hurt to quiet it a bit more for the riders in the rear bench (from the driver's seat its quiet enough in my opinion) so I'm planning on trying the turn downs that @Luckylindy fabbed up. It's now bearable in the rear and you can carry on a convo without shouting but for a few bucks I figured it's worth trying.

@Luckylindy Thanks for the pics...great idea. Are those elbows black PVC or ABS plastic? Looking at Home Depot it appears all the PVC is white and ABS is black. 

They must be ABS. I got them at home depot as well. Hope it works out for you. My wife used to complain about how loud it was in the rear bench and now says it's not bad at all. Report back how it is with silencers too. Probably be pretty quiet.

[drh]

@Luckylindy I got these tips put on last week - $39 for everything from Home Depot. Had to order in the elbows since my local store didn't stock them. I think it turned out really well. Here's a link with it running out of the water. I cut the tips to avoid the spray but I ran it before I cut them and it sounded even quieter like you said. In the water at idle you can barely tell it's running and once underway it makes a big difference too. I'll see if I can get a video of that for reference.

[Luckylindy]

@drh let me ask you this. Do you think the tips or the slip ins made a bigger difference? I actually lost a tip (hit a log or something, luckly no prop damage)  Had a lake trip before I could replace it so I pulled the other one to match. I was amazed how much louder it was and am considering adding the mufflers in case I lose another tip or something( or even to make it quieter). I will be trimming these new ones down so less likely to hit and get rid of the spray

[Woodski]

@Luckylindy:  FYI - I have the slip in stainless silencers in a 4" exhaust with straight baloney cut stainless tips, they do a decent job of quieting an open exhaust.  I added rubber flappers which lowered the noise level substantially.  I would guess the turn downs make a significant difference as noise is very much line of sight, so anything you can do to mask that helps.  Particularly on water as no blockages exist from transom to point of listening to sound emission.  The silencers reduce the sound level, the turn downs simply change direction (which is important).

[drh]

@LuckylindyIt's tough to say which has a bigger impact since I never had the turn downs on without the silencers already in. I still haven't rode in the back seat yet with the turn downs installed so I may get a better idea then. I should be able to get a video this weekend. I would guess that the silencers have slightly more impact but I think the turn downs help especially for rear seat passengers and those being towed. I can't hear the exhaust at all when I ski now at 15' off after I put the tips on. I will say the silencers seem to smooth out the exhaust note.

Edited August 3, 2017 by drh

[drh]

Here's a recording comparing the exhaust note before silencers and turn downs to afterwards. The first link

This was taken from the rear seat. Wind noise kind of conceals the difference but it is substantial. From the front seats it's even better. FYI for anyone interested in doing the turn downs, the black elbows are normally called an ABS closet elbow at most places. Goes from a 4" sipgot to a 3" hub fitting.

[UWSkier]

I think I'm going to try this mod on my RLX.  The inline mufflers that came from the factory are pretty free-flowing unless you opted for the silent rider versions with additional baffling and the crossover tube to equalize the sound pressure of the opposite banks firing.  I might also try taking my wedge off as I wonder how much of the noise from the back of the boat is just sound bouncing off the wedge.

[UWSkier]

@braindamage this is what I was talking about.  Going to try the Ghetto Home Depot turndowns first before I try fabbing up some insertable baffles.  Was out in the boat again this morning and really paid attention to where all the sound comes from.  It's all from out back.

[Chaabo]

Last year I installed Eddie Marine in-line silencers in my Response.

I cut out a piece of the exhaust rubber hose between the std mufflers and the STE tips.

I was prepared to loose some power, but surprisingly I can’t feel that the additional mufflers slowed down the boat at all.

Quieter - just a bit, but hey, every bit helps, right? Especially for early morning runs on a lake with concerned neighbors.

[UWSkier]

There's no shortage of flow on these boats.  Consider Nautique has been doing 2-into-1 exhaust for years with no issue.

While I love the sound of an unmuffled small block, I would prefer a bit quieter setup for my boat without breaking the bank on the baffled stainless downturns (which I'm not sure you can even get anymore).  I wish a V-drive Silent Rider would fit under the doghouse.  I like the exhaust note of my dad's '01 VLX with the Silent Rider more than my Response.  It's still throaty but less intense.

[Woodski]

@UWSkier - FWIW my 4" diameter exhaust system with the inline silencers plus adding a rubber baffle at the baloney sliced ss tips if a bit quieter than my neighbors LXI (I don't have the original in line fiberglass silencers as part of the system). Certainly not silent rider level of quiet but if you add the in-lines to your existing system it should knock the sound level down some more.

https://www.eddiemarine.com/shop/exhaust-and-accessories/mufflers/slip-in-mufflers-emi-xx

https://www.eddiemarine.com/shop/exhaust-and-accessories/exhaust-tips-and-flaps-1/angled-cut-end/test

 

[UWSkier]

6 minutes ago, Woodski said:

@UWSkier - FWIW my 4" diameter exhaust system with the inline silencers plus adding a rubber baffle at the baloney sliced ss tips if a bit quieter than my neighbors LXI (I don't have the original in line fiberglass silencers as part of the system). Certainly not silent rider level of quiet but if you add the in-lines to your existing system it should knock the sound level down some more.

https://www.eddiemarine.com/shop/exhaust-and-accessories/mufflers/slip-in-mufflers-emi-xx

https://www.eddiemarine.com/shop/exhaust-and-accessories/exhaust-tips-and-flaps-1/angled-cut-end/test

 

I wish someone made a 3.125" OD version of your first link.  Could slip them right into my factory exhaust ports ahead of the flappers.  Would modify them to include a couple set screws that would anchor right into the hard plastic wall of the factory ports. 

[Eagleboy99]

https://www.eddiemarine.com/shop/exhaust-and-accessories/mufflers

[UWSkier]

I went to Home Depot and fabbed up some ghetto downturns. Had to be careful installing to make sure the flappers still have room to open. First test is tomorrow morning. 

[UWSkier]

The ghetto tips worked great!  Sound volume inside the boat is reduced somewhat but the edge is taken off considerably.  Very nice sound actually.  Behind the boat, you almost can't hear it at slalom speeds.  Just hear the spray and the wind in my ears.  I never realized how much I could hear my boat especially on the holeshots with the exhaust firing straight back at me.  Not bad for $40 bucks at Home Depot.

For anyone concerned this might create a back pressure condition, fear not.  I cut these to be level with the back of the hull so they ride just at the surface when on plane.  My RPMs with these on today were actually slightly higher than they were with the same passenger load a few trips ago.

And yes, I have to clean up those cuts with the grinder.  I wanted to prove the concept before I spent more than 45 minutes on the project.

Edited October 25, 2019 by UWSkier

[UWSkier]

Here's a video I spliced together comparing the two.  Same passenger load, same crappy skier.  Unfortunately this camera sits directly above the engine mounted to a metal pole so the sound quality difference is less obvious than it is to passenger and skier ears, but if you watch with headphones, I'm sure you'll notice a little less "harshness" to the exhaust note.

https://photos.app.goo.gl/iqV9Vbg3kpXPbaAAA

Edited October 25, 2019 by UWSkier

[UWSkier]

Better sample video that tells the tale a bit better.

 

 

 

[Woodski]

Well, you managed to piss off the fish  . . . nice work