Going from 2” exhaust to 3” on PSC 37’

[Old Crow]

I’m repowering my 37’ PSC. Taking out old Yanmar 4JH2E, and installing a new 4JH5E. Requires going from 2” exhaust to 3”. As any 37’ PSC owner will tell you, area behind engine is tight in all axises. Has anyone been down this road? We’re familiar with various wet exhaust schematics such as those from Vetus, but they seem to assume unlimited fabricating room. Recommendations or references greatly appreciated.

[pcmm]

Originally Posted by Old Crow

I’m repowering my 37’ PSC. Taking out old Yanmar 4JH2E, and installing a new 4JH5E. Requires going from 2” exhaust to 3”. As any 37’ PSC owner will tell you, area behind engine is tight in all axises. Has anyone been down this road? We’re familiar with various wet exhaust schematics such as those from Vetus, but they seem to assume unlimited fabricating room. Recommendations or references greatly appreciated.

Should be the same exhaust for both engines. I repowered a couple of years ago with a rebuilt Yanmar 4JH2E and it requires a 3" exhaust also. not good that PSC used the wrong size for the old engine. I used a 3" centek waterlift muffler

[coopec43]

I thought a 3 in. diam exhaust was large for a motor that size but apparently not.

I came across this link which may interest you.
http://www.cruisersforum.com/forums/...ine-30731.html

And maybe this?
https://www.google.com.au/search?sou...30.oTETa0yp5hg

[GordMay]

Greetings and welcome aboard the CF, Old Crow.

[JOHNMARDALL]

Hello Crow,


If it will help, I can send you some basic slides from our exhaust system training module - they will help you to understand the key issues as you wriggle the three inch exhaust system into place. You can contact me direct at jmardall@comcast.net.
Best Regards
John Mardall
Vetus Maxwell Boat Equipment

[Baba Buoy]

The old 40 HP Volvo MD17 had three massive air filters and a 1 1/2" exhaust hose. A modern 38 HP diesel requires a 2" or 3" exhaust hose and has just one air filter with a 1" opening. This seems quite a flip flop for diesel engineering.

[S/V Alchemy]

I had a 2" I.D. exhaust that should have been 3". So I made it 4" and took an unusual route to do so. It may not be applicable to most boats or to your boat, but on the other hand, it could be done with a dual stern exhaust. I also have a Centek water lift muffler I quite like. By the way, my understanding is that the only way to truly learn whether your back pressure is too high or, conversely, that your prop pitch is wrong and your diesel is lugging, is to use an exhaust gas temperature (EGT) sensor or a pyrometer to see how hot the exhaust gases are getting.

https://alchemy2009.blogspot.com/2018/04/exhausting-reasoning-part-2.html

[wsmurdoch]

You might find a fellow PSC 37 owner to answer your question at https://www.sailnet.com/forums/pacific-seacraft/

Bill

[Old Crow]

Thank you all. This my first visit to this forum and it has been great. All good info and references.
With great appreciation,
Old Crow