Dual exhaust

[tonka329]

Looking at doing the dual exhaust set up on my boat since I am going to be replacing the 5.7 in it. Anyone know the maker or brand of dual exhaust for the Mercruiser 350? I'm wanting to do the exhaust out the back and not the side ones. Thanks in advance

 

[alldodge]

Looking at doing the dual exhaust set up on my boat since I am going to be replacing the 5.7 in it. Anyone know the maker or brand of dual exhaust for the Mercruiser 350? I'm wanting to do the exhaust out the back and not the side ones. Thanks in advance

There are several, installed Corsa silent choice on my cruiser. Can also just run pipes straight out the back and remove the Y pipe. Can do straight pipes, mufflers, and can also replace your cast iron manifolds with stainless or aluminum.

Not that hard to do, just decide what you would like to have

 

[tonka329]

I wasn't sure if I could "custom" make the exhaust. I can remove manifolds completely if I wanted to? Didn't know how hot they would get... I always thought you had to buy "kit" to keep the water cooled manifolds. Can you post any pics AllDodge?

 

[alldodge]

I wasn't sure if I could "custom" make the exhaust. I can remove manifolds completely if I wanted to? Didn't know how hot they would get... I always thought you had to buy "kit" to keep the water cooled manifolds. Can you post any pics AllDodge?

You need marine type exhaust system because they need to be cooled by water. You can use your manifolds and risers, then connect exhaust hose straight back to exhaust tips in the hull. Can replace them with ones from Eddie Marine like these
http://www.ebay.com/itm/like/160525345550?lpid=82&chn=ps

Here is silent choice installed which is a custom job

Here is eddie marine link and keep in mind there are other manufactures
http://eddiemarine.com/emi-thunder-exhaust/emi-thunder-exhaust-big-block-chevy

Here is mine with Corsa muffler tips prior to my engine rebuild


And silent choice


This is after rebuild and using turn down tips

 

[Bondo]

Didn't know how hot they would get...

Ayuh,.... If not water cooled, 'bout 1500?,..... Plenty hot enough to turn yer boat into cinders,...

It has to be water cooled from the motor, to the outside of the hull,....

 

[tonka329]

Thanks AllDodge. Is that ebay site for the Corsa brand? What do the turndown tips do for the exhaust?

 

[alldodge]

Thanks AllDodge. Is that ebay site for the Corsa brand?

No those are Eddie marine thunder exhaust manifolds and risers. There are different lengths and heights on risers, so once you decide which way your going you will need to pick ones for your motor and style.

What do the turndown tips do for the exhaust?

I pulled and had my motor rebuilt for performance, which included a high lift cam. The cam is what caused me to get rid of my Y-pipe for thru the prop exhaust, and my Corsa diverters and muffler tips. If These items were not removed I could have water reversion into the engine which could destroy it. It stock of slightly mild cam does not need to do what I did.

I like the exhaust noise to be reduced to minimal amounts when docking or coming along side other boats to tie up. Since I no longer have diverters to send the exhaust thru the prop, I installed turn downs so the exhaust exits under the water about 4 to 5 inches and makes it much quieter

 

[tonka329]

I guess that would make it quieter with the turndowns at idle. Then it gets loud during wake... I clicked on that link it it looks like those are $1,800 each? Do they make a more "economical" set of duals for the 350 5.7? Also, I'm getting and engine from a pick up truck. If I don't make a move on duals yet, can I use the same cam that is in the donor engine or will I need to change that out also?

 

[alldodge]

I guess that would make it quieter with the turndowns at idle. Then it gets loud during wake... I clicked on that link it it looks like those are $1,800 each? Do they make a more "economical" set of duals for the 350 5.7? Also, I'm getting and engine from a pick up truck. If I don't make a move on duals yet, can I use the same cam that is in the donor engine or will I need to change that out also?

The $1800 is for a pair not just one

The turn downs come out of the water when the boat starts coming up on plane. Keep in mind I have a big block which are louder then your small block.

You can use standard cast iron manifolds, or aluminum ones and risers. My link was showing you the entry level into the performance side. Sticking with a stock engine and cam you don't need to go performance.

Search around for mercruiser 5.7 exhaust manifolds, you will find things like this
http://www.amazon.com/MERCRUISER-COMPLETE-EXHAUST-MANIFOLD-GLM/dp/B004AQZA3W

Using standard stuff will work fine with diverters and thru hull, and just straight thru hull

Yes you can use a truck engine, you don't want a car engine (different cam). If you use a truck engine and you boat in fresh water, just change the freeze plugs. I'm saying this as your just using the long block and intake manifold, you will not be using starter, alternator, water pump, distributer or carb

 

[tonka329]

I will be using a truck water pump... Will that be ok for fresh water use with brass freeze plugs? Also, those manifolds and risers from amazon are ok to use for the dual exhaust? Im having difficulty understanding how the stock exhaust is set up. So, the truck engine will be ok with the stock exhaust for now?

 

[alldodge]

never

So, the truck engine will be ok with the stock exhaust for now?

Yes it will be fine, along with the water pump, just may not last that long but sometimes you never know. It's a seal thing but will not hurt anything

 

[tonka329]

Excellent. Thanks