Water Injection Elbow

[keepondancin]

I had to have an injection elbow made in Trinidad some years ago. A machine shop used mallable steel elbows, one regular elbow and one street elbow, forming the gooseneck (180 degree turn), that I needed. The machine shop drilled and tapped a nipple verticleinto the elbow for the water injection hose to be attached. Lasted for as long as I owned the boat, at least 5 years, and was a reasonable price.

[btrayfors]

In November 1990 -- some 21 years ago -- I needed a new exhaust pipe for my Perkins 4-108.

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!!

Bill

[delmarrey]

I made this one myself, not much toit. Just welded a steel pipe at an angle downstream. As long as water can not back up the exhaust, that's what counts.

.

[Celestialsailor]

Thanks everyone for your input. I can go ahead now and make one with confidence. I have a full Machine shop with TIG on the property here. I will buy scheduale 40 SS butt joint fitting. I'll probably make 2. Materials will be less than $40...thanx again

[lifeofreilly57]

While stainless mixing elbows may seem a good answer, my concern is with the order of sacrificial metals. Do you want to replace the relatively cheap mixing elbow or the very expensive water cooled exhaust manifold? The factory made cast mixing elbows are good for 15-20 years and are not exactly "cheap" but what is the cost over time? If your a decent fabricator you can make one from schd 40 or schd80 pipe by drilling a hole into a straight piece of pipe and adding an appropriately sized injection tube at a downward angle. Pipe it int o the back side of a "U" fitting (or 2 90deg elbows) on the exit side of the exhaust and you have a cheap home made mixing elbow. I agree that these may radiate heat but you can wrap it in commonly available header tape to alleviate that problem (available at any auto speed shop or online speed part distributor). Total cost $40.00 and a little fabricating. I made one for a boat I had 20 years ago when I was broke and was pleasantly surprised when I came across that same boat last year and found it was still working fine.
The current owner asked where I found the "custom" piece since it fit better than the original. Lack of money is the mother of invention.

[lifeofreilly57]

As an added comment, a syphon tube should always be used on the cooling water side.

[capngeo]

Here's one I did in stainless