Thru-Hull Exhaust Projects and U

[Cobra SX]

Hey Everyone,<br /><br />I Have a 20 foot Sea Swril, With a 302 V-8, and a Cobra SX stern Drive , Now i know that i have a through prop exhaust witch helps reduce Cavation.<br /><br />But i want to gain a little more power and at the same time give the boat that "meaty" exhaust tone<br />that you just hate to love as it flys past you down the lake...<br /><br />I have a Deck on the back of the Boat for Skier set-up , or swimmer's deck , or what ever the use.<br /><br />I would like to set it up under that deck.<br />So at idle the exhaust would be submerged.<br />and at plane it would be above water.<br /><br />Now heres were the Real Question's come in....<br /><br />1) What would I use to make a good seal on two exhaust pipes thruogh the hull? <br /><br />2) How do I make it so NO water would be able to get into the exhaust mainfold, when OFF or at idle.<br /><br />3)Are there any Regulations on wethier or not i can change the boat to that kind of exhaust.<br />(besides NOISE regulation)<br /><br />Thanks For any help on this guys

 

[ZmOz]

Re: Thru-Hull Exhaust Projects and U

http://www.overtons.com/cgi-bin/overtons/order/pdetail.cgi?20337++

 

[f_inscreenname]

Re: Thru-Hull Exhaust Projects and U

1 I used a 3-M sealer from U/S Boat (just off the shelf).<br />2 Flappers like stated in the above post.<br />3 Not knowing your area but if there are boats where you are with thru hull exhaust I think it would be safe to say you would be O.K. You could always call your Coast Guard office to check.

 

[Bondo]

Re: Thru-Hull Exhaust Projects and U

1) What would I use to make a good seal on two exhaust pipes thruogh the hull? <br />

Yep, <br />Like f_inscreenname says.........<br />The tailpipe will have a Flange welded on it......<br />Just Glue it,+ Screw it...............<br />

3)Are there any Regulations on wethier or not i can change the boat to that kind of exhaust.<br />(besides NOISE regulation)<br />

I've Never Seen, or Heard of Any Regs about it.....<br />Other than the Noise Limits.......

 

[Cobra SX]

Re: Thru-Hull Exhaust Projects and U

Cool thanks guys, But im still wondering what to do about plug'n up that old exhaust leading from my bellows to the Risers.<br /><br />And should i custom Bend the pipe to help keep water out, or will that just rob me of power?<br /><br />SO 3M seal will work plenty good... <br />(it will make a good water tite seal that can with-stand the Vibrations and Temp ?)<br /><br />What do you guys think about the Old exhaust route on how to plug it?<br /><br />I Run around on Lake Powell , and Lake Mead .<br />These are lakes that are out of AZ, UT.<br />I have heard alot of these style exhaust running around doesn't seam to be a problem for them...<br />So think we will be okay.

 

[f_inscreenname]

Re: Thru-Hull Exhaust Projects and U

The “Y” pipe bolts to the transom plate. Unbolt it, if you can get it out good for you but you will most likely have to cut it to get it out. Copy the flange on to a piece of metal (I used part of a aluminum street sign), cut out and bolt on to the transom plate with some sealer to cap it. You have to get rid of the “Y” pipe. First it cleans up the motor compartment and second you will need the room to run the new exhaust. <br /> “SO 3M seal will work plenty good... <br />(it will make a good watertight seal that can with-stand the Vibrations and Temp ?)”<br />Temp- should not be high due to the water running throughout the exhaust. Wet exhaust = cool exhaust <br />Vibrations- There should be a rubber elbow or straight section of exhaust pipe that will allow the motor to vibrate without pulling on the exhaust ports. Mine goes like this, exhaust manifold to a cast riser to a cast down piece to a rubber elbow (to take it from down to back) to the exhaust port in the transom.

 

[Dhadley]

Re: Thru-Hull Exhaust Projects and U

Just recently there was a complete listing of noise laws (state by state) in either Trailer Boat Mag or Bass & Walleye. It was quite attention getting as to what some of the fines were. <br /><br />I'd sure ask first.

 

[Bondo]

Re: Thru-Hull Exhaust Projects and U

If you post an email address, I'll send you a couple shots of my Pipes......<br /><br />Mine go Manifolds, Risers, Rubber Boot, 4 1/2" Out the Back............<br /><br />Home-Made, Of Course........... <br /><br />Getting the Y-pipe out is the Problem.....<br /><br />And, The Noise Thing........<br />They started checking boats in NY a couple years ago...... And before that, I got Sick of the Racket 12hrs a day Trolling.................<br />So,<br />I extended the tips Underwater.......<br />No Noise at Idle..... Passes Any Test in the book........<br />Up on plane it Rumbles kind a Sweet, <br />For a V-6, Anyway............

 

[wileecoyote]

Re: Thru-Hull Exhaust Projects and U

Hey Bondo, I have a 4.3 and would like to see pics.Send to wileecoyotemoore@hotmail.com

 

[Doug Durako]

Re: Thru-Hull Exhaust Projects and U

Cobra---there is a switchable unit----noise when you want it, quiet when you get sick of the noise.<br /><br />Most of what I have read says you won't gain power, unless you add headers to let more exhaust out and a bigger intake manifold/carb setup to let more air and gas in.<br /><br />The switchable ones attach with a rubber boot and have metal flappers with route the exhaust down to the drive or out through the pipes.