Water cooled exhaust manifolds. Quick rundown?

How exactly does a water cooled exhaust manifold work? Does the water being pushed out the exhaust by back pressure reduce power? Does anyone have any diagrams where I can see exactly how it works? I'm wondering if could convert a normal manifold to be water cooled, or build a water cooled one from scratch.

 

Unless you can cast iron, it is not a good option. Fabricating it with mild steel will corrode very fast. Have you done any internet search? There are millions of sites with diagrams of the internals of a wet jacket manifold. It is possible to fabricate in stainless, but the difference in heat expansion tends to make gaskets fail. What is wrong with a factory manifold?

 

Some low-end DIY's have copper tubing for coolant winded around the original manifold. Not very good cooling properties used in a closed engine compartments..

 

Hey, are you asking about a Water Jacketed Exhaust Manifold, OR a Wet Exhaust, OR Both? On some vessels, the Water Jacketed Exhaust Manifold is connected to the Primary Cooling Loop, rather than the Sea Water, Secondary Cooling Loop, and Wet Exhaust. In this design one must include capacity for the extra BTU's from the Exhaust Manifold but eliminates the problems with Salt Water Corrosion in the Exhaust Manifold. This way the only Corrosion is in the Heat Exchanger and the Wet Exhaust System. I see this design, in a lot of 58 Ft Limit Seiners in Alaska, and in the Gillnet Fleet as well. It is also used in larger vessels with Keel Cooler type systems.