please dont be a fool… do you think that anyone that actually found a way.. would place this on the internet for free.. the car will run on a mixture of ninty five percent alcahol and five percent water.. the engine pistons are forced down by a explosion of the fuel… can water explode.. ok.
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Let’s see, for you to run your car on water, it’s going to need to be "falling" water, and that’s going to limit your range to wherever you can drive while trailing a large hose that’s connected upstream on a river somewhere.

Or maybe you could build a car that has a water tower on it – that’ll work too – just take it easy on the turns!
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Yes, I have and know countless others who have.

I spent weeks trying out different HHO gens (all from ebay) and each one works so much differently. The ones in PVC pipes usually output a decent amount of gas (depending directly upon what electrolyzer you use in the water) but their crude design does not allow you to see what’s going on inside and you cannot tell if your mix is doing good or not.
Then there are the wire designs, which put out okay – but not the best.
I finally built one using the best qualities of different models all put together, and I output around 1.5-1.75 litres/minute – which is really good for the size of the generator and for the electrolyte I am using.

There are many factors involved in whether an HHO generator will work well or not. The major factors are:
1. what are the electrodes made of, how well will they conduct electricity and how quickly will they corrode?
2. What electrolyte mixture are you using in the water (electrolyte is required to make the water conduct electricity to split the hydrogen and oxygen)
3. how much oxygen are you involving in the gas out to the engine?
4. How many o2 sensors does your vehicle have and how will they react to the extra oxygen they will detect? (sometimes the o2 sensors will detect more oxygen and increase your fuel ratio to compensate for it – I personally have not had this problem, but have heard others record it)

Speaking from my personal experience with the generator I now use and build, I have literally TRIPLED my gas mileage.
At first, with a cheaply-built generator – I only got a 23% increase on MPG. But now with my new design, I have tripled my gas mileage.
So yes, it does work if you have the right Generator and if you know a little about the process.
References :
Experience.
Here’s my myspace page specializing on the subject of HHO gas along with ebay links to good generators: http://www.myspace.com/trinityenergies

Here’s an NBC news link on the subject: http://www.wptv.com/content/specialreports/story.aspx?content_id=74b15465-2ebb-49e0-acb1-939c4bb13a28