changing to thru hull exhaust

[dubge]

Was thinking of changing to thru hull exhaust mainly because I like the sound of it and was wondering the pros and cons to this. Is it a hard task to do yourself? What would I need to do this if so?

thanks

 

[eriediver]

Re: changing to thru hull exhaust

Your best bet would be to find a silent choice set up. That's what I had on my Century. That way with the flip of a switch you can have a loud thru hull or quiet. If you're mechanically inclined it's not too bad to do.

 

[wvit1001]

Re: changing to thru hull exhaust

Do everyone on and around the lake a favor and leave it the way it is. You won't pick up any horsepower or speed with the thru hulls but you'll contribute to the noise pollution.

 

[dubge]

Re: changing to thru hull exhaust

I,m on the ocean if that matters, but I do understand what you mean. I didnt think it would be an issue out there

 

[tommays]

Re: changing to thru hull exhaust

If you do not use some type of muffler in the system it will get old pretty quick


And i would agree on lakes it is a PITA to listen to BUT around here on the Ocean it does not seem to travel as far




Tommays

 

[dubge]

Re: changing to thru hull exhaust

I was thinking I would add a muffler in it as well, I dont want obnoxtious but I do like the sound of a throaty exhaust, like the sound of a flowmaster 50 series on a truck

 

[eriediver]

Re: changing to thru hull exhaust

that's what I liked about the silent choice. Nice & quiet while idling through marina etc. & I could flip the switch & open her up once I was out of the harbor.

 

[Bondo]

Re: changing to thru hull exhaust

If you're prepared to throw a Couple of Grand or More at it,......

You can find somebody to install thru-hulls......

Or,.....
If you're Handy,....
You could scrounge up the Parts,+ throw it together Yourself.........
ebay is a pretty good Shopping spot for stuff like That.......

 

[dubge]

Re: changing to thru hull exhaust

Yes I am pretty handy as long as I dont have to weld, never did it or have the equiptment. It is not really in the budget to spend a couple grand on it so if it is that much to DIY I might have to pass on this

 

[Acer2428]

Re: changing to thru hull exhaust

From what I can TELL by looking at boats with a thru-hull online, it's just a set of headers that exit and then you seperate the cooling system return asepct from the exhaust system, no?

If so, it would seem like this would save a lot of grief and hassle.

 

[wire2]

Re: changing to thru hull exhaust

I made a set of double wall stainless headers for my 5.7 Stringer.

Then instead of an elbow after the riser down to the mid-drive, I fabricated a 3" stainless tube "Y", then put a butterfly valve in the upper leg, which then goes out the transom. The butterfly is actuated by a 3/4" x 3" Bimba cylinder and controlled by a pneumatic switch on the dash, powered by manifold vacuum.

It does flow (very) marginally better than thru the prop. If I cruise at 4000 rpm and open the valves, it rises to 4100.

The reason for such a small improvement is largely due to the fact that exhaust flowing out the prop is efficiently being sucked out by the speed. A flared prop hub creates a LOT of vacuum at 50 mph.

I rarely open them unless someone asks to hear it. Then I usually get a thumbs up, and I close them again.

It's a novelty but it shore do sound neat!

 

[MikDee]

Re: changing to thru hull exhaust

Silent choice is great, but big bucks, What size engine do you have? That will determine approximately how loud it will be. I went cheap. I did it on 2 boats I had, one was a 20' SeaRay bowrider with a 228hp/305 or 5.0 litre motor, no mufflers, not that loud, but nice! The other was a 24' SeaRay Cuddy 260hp/350 and used a cheap set of rubber mufflers, again not that loud with the mufflers, like glasspacks. I just bought 2 sliced stainless tips I liked in the right size, took the marine exhaust hose, either 3", or 4" depending on your riser outlet size, put it on the riser (elbow) and extended it to the transom, made a mark at the transom, drilled a 3" pilot hole from the inside, then finished drilling the outside, filed it out with a round file, and put in the 2 sliced stainless tips. On the bigger boat, the mufflers took the place of the marine exhaust hose, an important note here: Use 2 hose clamps at every joint Coat Guard rules!

At least this is the way it works with Mercruisers, OMC's are probably a bit different.

 

[dubge]

Re: changing to thru hull exhaust

I have the 260HP/350
So you just disconected it from the riser and brought it straight back. Did you have to cap the rest of the exhaust that led down to the regular exhaust? That sounds simple enough.

thanks

 

[riverjet502]

Re: changing to thru hull exhaust

Word of caution hear... Check your state laws on this... Here in IA it is now illegal to even have the switch on the dash.... Thank you MN...

Mufflers and Noise Levels:

Any boat operated on the waters of Iowa must be muffled to effectively reduce vessel noise. An effective muffling system is required for the exhaust of each internal combustion engine and the use of cut-outs is prohibited. Specifically, it is illegal to operate a boat that exceeds a noise level of 86 decibels when measured on the "A" scale at a distance of 50 feet or greater.

 

[delsol]

Re: changing to thru hull exhaust

i have a cool looking carlson css 19' i fixed most of my problems with the boat. it runs good. this is a prime boat to do this on. after being on my buddys boat all july. i would never ever get the exhaust as its to loud..i have seen it on all high end donzi's etc...these suckers are loud..also can you burn you arm on them swimming???the switch one sounds way better
bob/philly

 

[Sorrento 25]

Re: changing to thru hull exhaust

I've been considering through-hull on my boat for a couple reasons. I think a 7.4 is choked off by the exhaust passages of an Alpha, a thru-hull system would be more fuel efficient, my drive will run cooler without exhaust passing through it, the engine should run cooler with a more free flowing exhaust, and a 454 benefits more than an 350.

In searching around I decided to go with some Primex fittings and Vernatone mufflers.

I may add some turn-downs that bring the exhaust outlet below the waterline when you are off plane. They also have a sound-reducing effect at speed because they direct the exhaust down instead of straight back. Gibson sells them for a small fortune, but I think I'll make them out of plastic and/or glass exhaust parts since its all hidden under the swin platform on my boat anyway.

 

[MikDee]

Re: changing to thru hull exhaust

I have the 260HP/350
So you just disconected it from the riser and brought it straight back. Did you have to cap the rest of the exhaust that led down to the regular exhaust? That sounds simple enough.

thanks

You'll want to run some kind of mufflers with this 350/260 engine, then it will be sweet, & mellow. I never bothered capping off the Y pipe, as there is a flapper down in the middle (but I never had one on my boats?), the water will reach it's own level in the pipe, and it is risky, but it is sucked out the prop when you're in motion, some people say capping it off causes a suction at the prop, which will slow you down.

Yes, my motors ran cooler, more free (less backpressure), with more oil pressure, and I don't care what anyone say's, I feel it's a horsepower gain!

 

[Bondo]

Re: changing to thru hull exhaust

I never bothered capping off the Y pipe,

That's a Dumb Idea,......
And,.....
It's also a Great Way to Sink your boat..........

I feel it's a horsepower gain!

Ayuh,......... And it All in Your head...........

Word of caution hear... Check your state laws on this... Here in IA it is now illegal to even have the switch on the dash....

Ayuh,........ I Agree,........ It's been that way for a few years now here in New York state.......

 

[riverjet502]

Re: changing to thru hull exhaust

What has happened around here in the past years is that numerous people with Colbalts, Rinkers, Mariahs, O lets not forget the Bajas dudes... These guys started running around with the "switch on the dash" thinking it was cool to have a tug that sounded cool. Well because of them we now have noise laws..Thank you very much. The DNR (Dam Noise Regulators) Are taking it to heart and use this as a method to just stop you as an excuss, Then look for other reasons to fine boaters. Do I sound bitter you dam right I am. The DNR used to leave us performance boaters alone till everybody started adding the switch. Just having the switch on the dash wether in use or not will net you a $165 fine. On a stock enigine with the stock merc exhaust it is a waste of money you gane nothing. Sure you are more free flowing but you still have the same exhaust manifolds. Those manifolds are open cambered. Meaning all your exhaust gets to bounce around from one cyclinder to the next. Lots of exhaust reverberation going on there. The money you spend on the noisy switch will buy to quality manifolds such as Gil, Eddie, Corsica. These manifolds have runners cast into them that scavage the exhaust night & day over the stock iron merc manifolds. Now you will see an rpm increase... Not trying to make anyone mad here, but for the money there is better options. The best option would be to spend the coins on a decent cam upgrade and work the heads over. Nothing says performance as a stealthy sleeper...

 

[MikDee]

Re: changing to thru hull exhaust

That's a Dumb Idea,......
And,.....
It's also a Great Way to Sink your boat..........

True, But at the time, I never realized how risky it was, I would not do it again. I'd recommend capping it off somehow, maybe a couple of 3" PVC one way vertical check valves. (water goes out, nothing comes in)

Ayuh,......... And it All in Your head...........

No, it's all in your head, that there's nothing to be gained. You can't make a statement like this, unless you've done it! and I have, more then once.

Ayuh,........ I Agree,........ It's been that way for a few years now here in New York state.......