thru hull location

[nitmoles]

i've got a 79 26' fiberform with a 260 hp mercruiser and alpha 1.
how much does the exhaust going through the sterndrive raise the temp. and would it be worth it putting thru hull exhaust? if so where? half the post say above the waterline and never under it... and the other half say below is fine. i would like the boat to still be fairly quiet and would prefer below.
any thoughts are appreciated.

 

[chaparall villain 2]

Re: thru hull location

i would say thru hull should definitly be above the water line but are you planning on running captains choice where the exhaust can go either way if not to run just out the back you also have to consider blocking off the underwater thru prop outlet most of the time the way the hard exhaust pipe comes off the manifolds dictates where to run it thru the hull as its pretty stiff ... good luck

 

[cr2k]

Re: thru hull location

And you have to pull the engine to block off the Y pipe.

 

[nitmoles]

Re: thru hull location

i wasn't really interested in the captains choice..... straight back all the time is fine by me... just not obnoxious.... the engine is out.. and i plan on blocking off the "y"
is heat from the exhaust a big factor on the drive? pushing a big heavy boat and all...

 

[Don S]

Re: thru hull location

how much does the exhaust going through the sterndrive raise the temp.

It doesn't raise the temp at all. If you have a temp problem, it's not from how the exhaust is routed. You really need to find the real problem and not start changing things that have nothing to do with an overheat.

 

[nitmoles]

Re: thru hull location

thank you for clearing that up. i don't have a problem. i was just trying to avoid extra heat in the worked alpha.... i read (no doubt in some other forum...) the exhaust raises the operating temp in the drive. i have the engine pulled, doing stringers and repowering (383 maybe..?) and thought this would be the perfect time if i would have benefited from thru hull

 

[Don S]

Re: thru hull location

If you don't have burned gear lube when you change your gear lube yearly, then it's not a problem.
There are drive showers out that cool the drive, but in most cases, it's not necessary.
Thru Hull exhaust is not the cure, and the noise is more of a problem than overheated drives.

 

[chaparall villain 2]

Re: thru hull location

i am running a 383 stroker in mine and i will tell you if you decide to stroke it make sure they figure the compression ratio and get it down to at the most 9:1 if not good luck finding fuel on the water to keep from detonating it . also watch how big of a cam you put in it too big and too much lobe and you will definitly loose all low end power and torque i love the lobing sound but chose a prop for torque and power and i am very happy with it .... good luck . ps make sure you buy that block off plate and just remove the y pipe and block it off if you go thru hull

 

[chaparall villain 2]

Re: thru hull location

oops where i said i chose a prop i meant cam

 

[wire2]

Re: thru hull location

.... ps make sure you buy that block off plate and just remove the y pipe and block it off if you go thru hull

Why?
Fabricate a "Y" with stainless tube and leave both connected. It's much less work than pulling the engine. And gives less restriction.
And it lets you add a butterfly valve in the thru hull pipes to run quiet.

.... if so where? half the post say above the waterline and never under it... and the other half say below is fine. i would like the boat to still be fairly quiet and would prefer below.
any thoughts are appreciated.

Keep in mind, pipes exiting below the water at idle will be quiet, but the entire back of the transom is out of the water when on plane.