6" to twin 4" Exhaust

Whaler1777 · Post by **Whaler1777** » Nov 1st, '06, 23:57

Hey fellas havent made any posts recently, been busy as heck... Been workin on Summer Winds in my free time... The big ol' DD's are comin out soon and I'm tryin to get my hands on an enclosure to keep her protected from the elements of a Northeastern winter... Hope all is well with everyone.... Now the question that I have is... I am looking to put in a set of 315 reman cummins in her over the winter and the exhaust outlet on them is 6" My boat has dual 4" exhaust ports in the back I was wondering If I needed to seal one of them up and make one 6" port or can I simply use 6" all the way back and get a fiberglass piece that will split the one 6" into 2 separate 4" ports? Hope that isnt too confusing.. Thanks in advance!! I will try to get some new pics up asap!
-John

Rawleigh · Post by **Rawleigh** » Nov 2nd, '06, 08:50

Congratulations on you acceptance. I'm not an expert, but I don't see why you couldn't split the exhaust. Two 3" would be too small, but I would think two 4" would work. The experts will be along soon to give you some meaningful advice though!!

CaptPatrick · Post by **CaptPatrick** » Nov 2nd, '06, 09:33

John,

One 6" round port gives you 28 1/4 sq in of free opening. Two 4" round ports is 25 1/8 sq in of free opening. That's 3 1/8 sq in less than the single 6" port, but should be close enough...

Doubt that you'll find a ready made fibergalss connector to fill your needs, so you'll probably have have them custom built.

Congrats on the NYPD acceptance & good luck with the Academy.

Br,

Patrick

IRGuy · Post by **IRGuy** » Nov 2nd, '06, 10:23

John...

I have 1996 Cummins 315 HP 6Bs in my '83 B33 FBC.. you will love them!

Congrats on being accepted to the Academy! Between your desire to be on of New York's FINEST and being a Bertram owner I know you are a good guy!

Frank B.. aka IRGuy

scot · Post by **scot** » Nov 2nd, '06, 12:20

Congrates on your acceptance.

I have pondered the split system based on your same reality "2 existing thru hulls" What always bothered me about this is the distribution of the exiting water.

Is it posible that the water could become unequal in the distribution at the "Y" and cause one side of the exhaust to be dry, or at less have insufficient water to cool the piping...causing it to melt or burn up???

Scot

Rawleigh · Post by **Rawleigh** » Nov 3rd, '06, 08:30

If you split it at the transom it shouldn't be that hot.

bertram31.com

6" to twin 4" Exhaust

6" to twin 4" Exhaust

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