Re: Water Injection

Posted by DavidM On 2013/10/29 17:40:45

Thanks Gusha for an excellent collection of references on this interesting topic, the following from the Wikipedia reference struck a chord:

"Some degree of control over the water injection is important. It needs to be injected only when conditions within the engine would otherwise be sufficient to cause detonation or other undesirable effects. This normally occurs when the engine is heavily loaded and running at full power, however may occur outside of these times in specialized engines or applications. Otherwise injecting water cools the combustion process unnecessarily, resulting in negative effects such as reduced efficiency or power."

This indicates why the simple, largely DIY devices, like the early "Mist Master" unit above were not very effective although the NZ article suggests otherwise.

With modern engine management systems using a computer to precisely control mixture, ignition timing and valve timing it would surely be possible to introduce water with the same precise control over flow rate and timing. I would guess it is not necessary because the modern controls have the combustion conditions close to optimum.

I think Dave's suggestion for controlling pre-ignition in our Packards by increasing the octane rating and advancing the spark is the most practical solution. The power and fuel savings claimed for water injection must be regarded with a great deal of scepticism and improved engine cooling as originally raised by JP does not appear to be a benefit.