Changing to Thru-Hull Exhaust

[spook322]

I presently have an 18 foot runabout with a 4.3 v-6 Mercruiser I/O board. What do I need to do to change the stock exhaust system over to Tru-Hull Exhaust? Is there block offs or can it be done easily?My thinking is that my present exhaust manifolds will work with the mufflers and flapper exhaust valves, plus blocking the lower exhaust outlet. Am I way off base or is this impossible? Thanks inquiring minds want to know.

 

[Bondo]

Re: Changing to Thru-Hull Exhaust

Sure,...... It can be Done...........<br /><br />You can Pull the engine to remove the Y-pipe,+ install a block-off plate on the drive........<br /><br />Then add the pipes out the hull......<br /><br />You're Not going to like the results though........<br />And Open-Exhaust 4.3l Sounds like a small Plane flying over...... Not Very impressive........<br />I Know,....... That blue boat in the pic. is a 4.3LX, with 4 1/2" thru-hulls......

 

[WillyBWright]

Re: Changing to Thru-Hull Exhaust

Check your drive exhaust plumbing. Most have an exhaust bellows between the transom and drive. But there is a tube available that was mostly used on v-8s that might get you a touch more performance with little trade-off. It doesn't connect to the drive, but just fits loosely around the fitting when the drive is down. This allows the exhaust to breath easier. It's only slightly louder. It's like going up to the next size larger exhaust pipe on a car. I don't know the price, but it's gotta be cheap.<br /><br />The bigger the motor, the more advantage that little item has. The drive flows plenty of exhaust, enough for a smallblock. More than enough for a 3L and 4.3L. So those motors won't see a whole lot of benefit. It's the bigblocks that really benefit the most. But I think it's worth a try.

 

[Laddies]

Re: Changing to Thru-Hull Exhaust

Before Mercury came out with the tube willys talking about ( it was installed on the early Ford V/8 to stop them from popping the upper exhaust bellows inside the boat) we were told at service school to cut the outside bellows like todays Cobras are. You might consider this first, because I don't know anyone with transom exhaust that don't tire of them

 

[Don S]

Re: Changing to Thru-Hull Exhaust

Here is another possibility. Corsa Performance has a diverter sytem that gives you your "Thru Hull" performance, but when you want it quit, you can run it through the prop like normal just by flipping a switch on the dash.<br />I've installed them on 350's and 502's, see no reason they couldn't be put on a 4.3.<br />Their website is kind of usless, and lacks specific information, but gives you an idea of what the product is.<br /><br />Corsa Marine<br /><br />

 

[wvit100]

Re: Changing to Thru-Hull Exhaust

Your not going to make any more horsepower with through the hull exhausts and your going to annoy everyone in the boat and in the general area with the wimpy rice burner sound from the 4.3.

 

[mercrewser]

Re: Changing to Thru-Hull Exhaust

You'll also devalue the boat.

 

[f_inscreenname]

Re: Changing to Thru-Hull Exhaust

what Bondo said.

 

[flashback]

Re: Changing to Thru-Hull Exhaust

You won't be so PROUD !!!! when you hear the LOUD.