In November 1990 -- some 21 years ago -- I needed a new exhaust
pipe for my Perkins
I got a local automotive muffler
shop to weld a 1" water
injection pipe at an angle onto a standard curved galvanized exhaust
pipe. I bought a new flange for the exhaust manifold and fit the new exhaust pipe to it (I've forgotten if it was welded or not).
The pipe attaches to the engine
at about a 45-degree down angle, with the water injection downstream of the curve and about 4"-6" lower than the exhaust port.
I wrapped the exhaust pipe above the water injection point heavily with asbestos tape (I think, or it may have been Teflon).
Cost for welding up the pipe...materials and labor...was $73.50.
The pipe has been great for all these years. No problems whatsoever after many thousands of sea miles and coastal cruising miles, including powering up and down the ICW
a few times.
I keep waiting for it to fail. So far, it hasn't. One of the best investments I've made for the 4-108!!