looks like a lot of fun. As you mention, repowering a trawler
with a tractor engine
isn't for everyone, and there are lots of things which must be considered. Seeing as you threw the project
out there, I thought I might make a few comments that might save some grief down the road.
The piece of stainless steel
art that you refer to as an exhaust
manifold might more properly be called an exhaust elbow
or riser. From the photos, I see that it is probably designed to bolt onto the factory dry manifold at the two bolt flange. What I can't see are any other brackets to provide additional support. This is a rather long heavy part to support only with the two bolt flange, and when it gets full of water
it will be even heavier. Without substantial additional support it will almost surely crack or cause the dry manifold to crack.
As I understand your drawings, the freshwater coolant
will enter close to the exhaust pipe entrance, and exit on the bottom on the other end of the unit.
The problem I see here is that there will be a large amount of air trapped at the top of the rise, with no way to purge the air out. This air will cause expansion problems within the freshwater coolant
system. I suggest you add a bleeder valve at the highest point of the water
jacket to get rid of the air when the system is filled.
This system will probably last for many years, but welded stainless exhaust systems in contact with salt water
have a history
of pitting in and around the welds. When pitting occurs the engine coolant will dissappear out the exhaust without a trace.
I think the heat exchanger
you have chosen will have enough heat rejection capacity for the engine, as well as the heat that will come from the exhaust elbow
, but just be sure the plumbing
on the freshwater side of the system is as direct as can be, and has low pressure drop. You want to be sure the circulation pump has the ability to push an adequate volume of water.
Good luck with the project