On ship sized Diesel engines, water injection is used to lower combustion temperatures to lower Nitrous oxides. On our relatively small Diesels in our buses, I would not fool with water injection. True the right amount will lower combustion temperature, but inject just a bit to much, and you could get hydro lock bending a rod, blowing the head or blower, etc. Personally- I wouldn't fool with it. If your engine is turbocharged, get a good quality air to air intercooler custom made to your bus-it will be the best thing you could do. I sell big rigs (Freightliner and Western Star) and I have yet to see any of the big Diesel engine manufacturers (Caterpillar, Cummins, Detroit Diesel, International, DAF, MAN, Volvo, etc) have the option of having water injection on their engines. If it worked so well-don't you think the engine manufacturers would be using it-how simple would that be? Good Luck, TomC
Not to argue with you...especially given you experience. The "but" that follows isn't anything more than additional comment and question.
The info on the ship's mamouth D plants using water injection is, of course to me, news. Not knowing, I wonder that ships need to meet any sort of air quality or efficiency regulation that would lead them to water injection systems for air quality motives. That leaves efficiency and power as the rationale. The mfr.s of the automotive systems have an abundance of info concerning power/efficiency increase. From what I gather, you get a power bump for a given volume of water injection and you get more for an additional increase and there must be a optimum ratio per given engine. My point being that you can get some benefit for a small, less than optimum, injection quantity. In my life experience, taking it to the "limit" has associated risks and down sides.
I have emailed a couple of these companies about the benefit of straight water injection sans meth but haven't, as yet, gotten a response. Junkman, as well, hasn't responded with a clarification of his post. I hope for some feedback, still. Your sharing sure makes you stand out, at least at this point.
"Hydra lock" is, as you pointed out, a disaster. Long ago I was told that injecting water into the intake charge air stream would cause the valves to warp. Throwing caution to the wind I ran a stream of water into my heavily used and abused VW engine to remove carbon. I did this every few months to correct "ping" on heavy and prolonged load. It worked and when I tore the engine down the second time I found it pretty much carbon free.....anywhere. Never bent valve but I am not taking issue with that caution. In this case, I think we are talking about very small quantities in comparison and even then only at high throttle settings.
I cannot imagine anyone arguing with the wisdom of a quality and properly sized Inter cooler. Leave no doubt that I share your opinion. I am not in any way implying that the IC should be eliminated. I could see where if water injection was part of the design you would require a smaller IC to achieve the same charge air temp drop. But why not get the max for the max and design for non-water injection.
These guys talk about water injection but in reality they mean "water vapor". Liquid water isn't introduced to the combustion chamber. They either finely atomize the water near the engine intake or more crudely break up the stream of water and introduce it prior to the IC. Regardless, liquid water isn't intended to reach the cylinder.
I can't get on-board with your rationale that the Big Guys not doing something proves much of anything. They didn't use catalytic converters, or uric acid injection, nor EGR nor retarded exhaust valve timing or even all those fancy injectors....not to mention high fuel pressure Common Rail till they were forced into it. Even low sulfur, despite the obvious benefits, was forced upon the manufactures. And let us not even go to lead as a topic. They are motivated by more complex "stuff" than "is it a good idea" or will it really work. Lots of stuff in the decision mix even besides Gummint meddle'n.
Thanks for your info Tom. As usual, I hadn't a clue.