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Old 11-28-2011, 01:02 AM   #6
ontic OP
Joined: Jul 2008
Location: Melbourne
Oddometer: 1,070
Originally Posted by Tosh Togo View Post

Just so the OP knows what he's getting into, here's how the big boys used to do it.
LOL, yeah, um, I was thinking something a little lower tech

Have no worries, at the moment this is firmly located within the 'thought experiment' phase, a phase it may very well never leave.
I was originally curious about water injection when I was looking into running my diesel 4x4 on recycled oil (two tank system), but didn't even look into the water element properly due to giving up on the whole idea because of the huge messy hassle of it all. No thanks, I'll just buy my diesel, I don't use much of it anyway.

As has been noted by others, I have also noticed how much an engine seems to love running in a good thick heavy mist/fog.

Originally Posted by Rucksta View Post
Windscreen washer components and fish tank supplies would be a good place to start looking for parts
Water can be injected upstream as far as the air filter and high pressure is not required.

I've never done it or seen it done on a normally aspirated engine but it works well on turbo motors but they generally have much more sophisticated engine managenment systems than you'll find on an airhead.

I'm not sure how you would determine when, how much or how long to inject water on an airhead.
So far I've come across two low tech versions which I've had a brief scan of, both using very different approaches, one that seems to let the vacuum in the carb suck water up a tube then out through a hypodermic needle into the carb, and the other that seems to let the vacuum in the carb suck air through an (aquarium) air stone, bubble it through water (like a bong) and then continue sucking that 'moist' air into the carb.
In one you probably get a variable amount of small drops of water sucking straight into the combustion chamber and in the other you probably get a very tiny amount of moister air getting drawn in (along with the regular fuel air mix). Both of them seem pretty rudimentary, but are interesting for this difference being at opposite ends of the spectrum- a tiny tiny bit of slightly wetter air, or water straight in there..

It seems that most good examples injecting water do it only at high power. (and as this is where pinging occurs for me when it happens this would be the goal)
I wonder if it could be as 'simple' as having (kind of) a seperate carburetor- basically just another float bowl for water and another main jet for water. Would water even work like gasoline through 'another' main jet in the carb venturi? Or is it just too thick and errr... unvolatile...Would we aiming for proper vaporisation, or is fine droplets OK?

The above example, of a main water jet, is trying to think of developing something whose on/off and stages between is basically managed by the carb (and tuned I suppose through the float level and jet size, etc.)

Lets say that water won't be sucked out of jet comparable to fuel, another possible element could be a gravity fed system (without a float bowl) run first from a tank above the carbs, through a basic flow regulator, then to a valve that was controlled by another throttle cable (via a splitter). This could then feed into the water main jet at the carb. The idea being that at (or near) full throttle the valve starts to open, and the slightly pressurised water flows out of the main jet and is vaporised/dropletised in the venturi... things to tweak now would be, the flow regulator, when/where on the trottle position the valve starts to open and how much, and the jet size...

Originally Posted by Lornce View Post
"Water Ingestion" would have been a more accurate description.

Worked pretty well and had the side benefit of steam cleaning the combustion chambers. Not the sort of thing you can "fit and forget", mind. Requires fairly constant attention and fettling.
For the sake of the thought experiement it would be nice to try to think of something that was: fit, turn on or turn off, and maintain... constant attention and fettling sound slightly less appealing (at least in the long run).

cheers guys,
don't feel shy to throw some ideas around here, I'll be the idiot in this thread.
1974 R90/6
1981 R80G/S
1994 XLR250R
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