Converting to thru hull exhaust?

[Darkhorse1201]

I am thinking of converting my 4.3 OMC I/O to a thru hull exhaust (for performance, sound, etc.) The conversion would be fairly easy as it is a straight shot from the back of the manifolds to the transom - just need some pipes, clamps and flappers. My question would be what to do with the old exhaust - does it need to be capped or plugged someway to prevent the water from enetring the boat? And what would be the best way to do that? Thanks!

 

[Don S]

Re: Converting to thru hull exhaust?

(for performance, sound, etc.)

Performance will not be noticable.
Sound from a V6 is more like a model airplane (as mentioned by several here). Not the roar of a V8 engine that you might expect.

They make kits for this so you can use both setups. When around other people, you can still run thru the prop, and at the flick of a switch sound like an airplane.

 

[delsol]

Re: Converting to thru hull exhaust?

i dont know much , but check you area as i read where its against the law in some states..the loud noise they claim they can ticket you???? i thought i read that and will pass it on
bob

 

[mtnrat]

Re: Converting to thru hull exhaust?

I think you will be disappointed. It will be loud with a mind piercing note to the exhaust and you will see basically no performance increase. Even with a SBC there is zero to little performance gain at the rpms we are running, but at least a V8 would sound ok to the driver, but annoying to most other boaters around you.

 

[MikDee]

Re: Converting to thru hull exhaust?

I had dual 4.3 205hp Cobra V6's in my 1986- 22' Celebrity Super Sport Cuddy with thru hull exhaust, it was installed from the factory just under the waterline, and actually sounded nice, but a bit truckish, and it wasn't too loud!
Here's a ratty looking Pic, but you get the idea, look closely just under the swim platform:

 

[stinger222]

Re: Converting to thru hull exhaust?

Don't mean to be sound confrontational, but if you are interested in increasing performance, why did you get a boat with a V6? And I agree with the others, a v6 with open exhaust will sound like a buzzing lawnmower, sort of the like the teenagers in my neighborhood driving the ricers around with the coffee can mufflers. Actually there is one kid on my street who has a 69 camaro with...his dad brought him up right!!!I enjoy hearing that thing go by.

Save your money towards dropping a v8 in there, then it will sound nice and perform nice too.

 

[HT32BSX115]

Re: Converting to thru hull exhaust?

When I had the Infamous King Cobra 460 in my Liberator I had the Corsa Capts Call diverters connected and could switch from thru hull to thru prop at will.

Every time I went to thru hull, everyone in the boat would yell TURN IT OFF!! TURN IT OFF!!!!!!!

It didn't make ANY difference in performance...


When I put the 454 Mercruiser in, I omitted the thru hull.

I checked the laws in Wa State and other western states and it appears that I could still use the thru hull since my boat is a 1987 model and there's some sort of grandfathering for boats made before 1990.

There's also muffers made for thru hull boats nowadays that do reduce the noise somewhat. (They're not cheap)

I just decided they're not really worth it.


Cheers,


Rick

 

[krisnowicki]

Re: Converting to thru hull exhaust?

I have a thru hull and it uses pvc pipe is this normal?

 

[Manipulator]

Re: Converting to thru hull exhaust?

You would want to cap off where your pipes go down and enter into the out drive. You can find rubber caps where you slide a clamp around them to hold them in place. As far as plumbing, I would use exhaust hose and run it to exhaust tips that have the flappers built into them. I assume this is a Cobra drive. A Stringer would require some inventive wisdom as the engine lifts up and down to trim the boat.

 

[whywhyzed]

Re: Converting to thru hull exhaust?

grandfathering for boats made before 1990.

Interesting..... The law here is 1960!
only boats manuf. 1959 and earlier can exit above water without mufflers

 

[Manipulator]

Re: Converting to thru hull exhaust?

I sure would like to see thru-hull on a Stringer. See how it was done.

 

[mtnrat]

Re: Converting to thru hull exhaust?

Hmmm V6 eh. Sounds like a waste of time, energy and money.

 

[skeat]

Re: Converting to thru hull exhaust?

You won't see much difference if any but right now you have a quiet boat that people think really moves, with the open exhaust you'll have a loud boat that people will think is slow (as the V-8 racers scream past you)

 

[Manipulator]

Re: Converting to thru hull exhaust?

What is the deal? If the dude wants open exhaust let him have it. Quit trying to talk him out of it just because you don't like it or want to hear it. I think he should put a couple fart cans on it while he is at it.

 

[skeat]

Re: Converting to thru hull exhaust?

The guy is posting a question on a forum, take out of it what you want and disregard the rest. The purpose is to benefit from others experience

 

[MikDee]

Re: Converting to thru hull exhaust?

As I said, it will probably sound like my old boat, almost like my S-10 Pickup with a flowmaster on it, not bad, but no V8. A coupla 3" center riser manifolds, & elbows, plus some 3" rubber exhaust hose (to mellow it out some) to the 3" stainless tips, and Block off the Y-pipe.

 

[Don S]

Re: Converting to thru hull exhaust?

It's still an old thread someone brought back to life.

 

[mtnrat]

Re: Converting to thru hull exhaust?

It's still an old thread someone brought back to life.

I must look at the thread dates. Pretty irrelevant now.

 

[Lou C]

Re: Converting to thru hull exhaust?

The V-6 with the standard exhaust actually has a nice sound to it, but I can see why people would think it's objectional and not the V-8 sound you'd want with a thru the transom exhaust. Kinda like a Jeep Cherokee inline 6 with a low restriction muffler. Sounds more powerful, but not V-8 nice.
Only reason I can see to do it on an older OMC 4.3 is because you can't get those one piece manifolds anymore.