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UWSkier

Ghetto Exhaust Downturns: with video

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UWSkier

Posted about this in another thread but to make it easier to search, thought I'd post its own.

Based on feedback from @drh and @Luckylindy about this mod, I decided to give it a go myself.  These guys get all the credit for trying this first.

This project requires Qty 2 Clay to PVC 4" flexible couplings (Nibco) and Qty 2 4" to 3" fitting ABS or PVC closet elbows.  I went with ABS because I wanted everything to be black.

If you have a Wedge, you will need to carefully shave down the Nibco a bit to get enough clearance for the fitting to seat up tight against the hull without the Wedge bracket making that an impossible task.

To shave down the Nibco, one of these makes quick work of the task.  Be careful to not cut all the way through.  You have to remove quite a bit of material.

63113_W3.jpg

Use the wide cutting blade and it's like a warm knife through butter.  Hooray for Harbor Freight!

You have to cut off the 3" flanges so they're not dragging in the water.  I set mine so they were about 1/4" to 1/8" above transom level.  This photo was from a rough cut.  I've ground down the unevenness in the final product.

IMG_20191024_091402.jpg.6f7da273ca2fba40

When you install, if leaving your flappers on, make sure you don't push the elbows up tight to the hull.  Give them room to do their thing.

From a flow perspective, these add no restriction.  WOT RPM and top speed tests with these on actually showed a slight increase in performance (different days, but you get the gist).

As for how they work to quiet the boat...  Noise level in the boat is lowered a fair bit.  At speeds around 25, it's WAY quieter.  At slalom speeds, it's a fair bit quieter in the boat and the sound is less intense.  BUT, behind the boat is where you notice a gigantic difference.  Check out this body cam footage of with the tips and without.

 

 

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Eagleboy99

That's quite a difference in sound!  Would be interesting to see what a decibel meter actually reports. 

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Eagleboy99

Curious:  why not a 4" stright adapter?  Why 4 to 3?

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UWSkier
1 hour ago, Eagleboy99 said:

Curious:  why not a 4" stright adapter?  Why 4 to 3?

Exhaust ports themselves are only a bit more than 3" and with a flapper obscuring a fair bit of it.  That and I don't think there's such a thing as a 4" to 4" closet elbow.

039923197306.jpg?size=xl

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Eagleboy99
UWSkier

could try that.  I wanted something I could run right at the water level.  There's no restriction with the reduction from 4 to 3 as there's already 3 upstream and baffled Primex mufflers inline.

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Eagleboy99
2 hours ago, UWSkier said:

could try that.  I wanted something I could run right at the water level.  There's no restriction with the reduction from 4 to 3 as there's already 3 upstream and baffled Primex mufflers inline.

Good point.  I have to say I love the engine sound of my RLX

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ahopkinsVTX

Nice! That is a huge difference. I too love the sound though. It makes me smile even if I just hear my friends on the lake and I’m going to work or something. Loved my TXi and that’s with the ste tips and silent rider exhaust. 

https://youtu.be/Ooun-LM3Q-s

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UWSkier
17 minutes ago, Eagleboy99 said:

Good point.  I have to say I love the engine sound of my RLX

Still sounds great in the boat, just slightly less gargly.  It's an improvement for sure.

Here's the sound comparison from a camera right above the engine.  Difference is less obvious there than where human heads go, but you still get a nice sound in the boat.  Just a slightly less intense one.

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

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UWSkier
3 minutes ago, ahopkinsVTX said:

Nice! That is a huge difference. I too love the sound though. It makes me smile even if I just hear my friends on the lake and I’m going to work or something. Loved my TXi and that’s with the ste tips and silent rider exhaust. 

https://youtu.be/Ooun-LM3Q-s

That does sound nice.  It's a bit more rumbly than with just the Primex mufflers on mine.

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ahopkinsVTX
5 minutes ago, UWSkier said:

That does sound nice.  It's a bit more rumbly than with just the Primex mufflers on mine.

There are a few responses on our lake like yours that ski a little after us. They definitely have a more distinct sound than my TXi did. I understand toning them down a bit. The surprising thing is my friends 2011 Response with the LS3 is probably the quietest. Even when he hammers it. 

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braindamage

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UWSkier
7 minutes ago, braindamage said:

Would the tighter elbow/closer to the transom exit matter?

maybe this?

90 Degree Elbow Coupler Silicone Hose 4-Ply 4-inch for Turbo/Intercooler/Intake Piping,Length 102mm Thickness 5mm with T-Bolt Clamp https://www.amazon.com/dp/B07XJBVF7K/ref=cm_sw_r_cp_api_i_vr5TDbFMJKD3G

That's silicon hose. Probably crush. You need PVC or ABS

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drh

These made a big difference for me along with Eddie Marine slip in silencers. I don't get any exhaust sound behind the boat at slalom speeds just like @UWSkier showed. And here's a clip of my factory exhaust before the mods for comparison. This is no mufflers, just flappers: https://www.amazon.com/photos/shared/BrgiZGaCTcyuVsVPqX_uoQ.PvW50SUvlpMzeUebqw1ml8

If anyone does this I would periodically check the tightness of your hose clamps. I just lost a tip a few weeks ago and have to replace. I wasn't able to find the elbows at Home Depot anymore, even online, so I ended up finding one at a decent price here: https://www.google.com/shopping/product/16529278853125955748?prds=epd:14744833323634945309,oid:14744833323634945309,prmr:3&sa=X&ved=0ahUKEwi0lNPGusDlAhXEneAKHVqSBgcQ1sEDCCw

 

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UWSkier
7 minutes ago, drh said:

These made a big difference for me along with Eddie Marine slip in silencers. I don't get any exhaust sound behind the boat at slalom speeds just like @UWSkier showed. And here's a clip of my factory exhaust before the mods for comparison. This is no mufflers, just flappers: https://www.amazon.com/photos/shared/BrgiZGaCTcyuVsVPqX_uoQ.PvW50SUvlpMzeUebqw1ml8

If anyone does this I would periodically check the tightness of your hose clamps. I just lost a tip a few weeks ago and have to replace. I wasn't able to find the elbows at Home Depot anymore, even online, so I ended up finding one at a decent price here: https://www.google.com/shopping/product/16529278853125955748?prds=epd:14744833323634945309,oid:14744833323634945309,prmr:3&sa=X&ved=0ahUKEwi0lNPGusDlAhXEneAKHVqSBgcQ1sEDCCw

 

I'm either going to glue mine in place with silicone, or drill a few holes in the exhaust port flange and put a couple small bolts through them.

My Home Depot had these in a box.  They were super dusty.  I don't think they sell many, and I can't find them on their website anymore either.  They were just there a week ago.

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justgary

When I switched from flappers to STE turn down tips, I noticed that the tone mellowed a lot.  The flappers are creating the higher pitched popping noise.  Removing them completely is the way to go, but only if you have securely fastened turn downs that keep you from eating too much water in reverse.  The stainless ones are baffled to help with that.

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mackie12

its funny how the grass is always greener......I have S/S turn down tips but kind of wish I didn't as I like the sound without. However, at 6:00 am I sure everyone likes the tips/quiteness....... 

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drh

@UWSkierI took just the elbow off yesterday to match up the cuts with the new one I got in and I noticed that my flapper hits the inside of the reducing coupling. Did you notice this on yours? I'm thinking about removing the flappers in case that is causing a restriction. 

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UWSkier
12 minutes ago, drh said:

@UWSkierI took just the elbow off yesterday to match up the cuts with the new one I got in and I noticed that my flapper hits the inside of the reducing coupling. Did you notice this on yours? I'm thinking about removing the flappers in case that is causing a restriction. 

I clearanced the flappers by holding them open and sliding the fitting into the coupling only until it lightly contacted the open flapper. It might touch just a bit but it has plenty of space to swing open with how I've installed mine. 

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