kstyer said: You do not want to use a water injection system on a computer car with an oxygen sensor. The water releases oxygen when in the combustion chamber. The extra oxygen is great for the car, but will fool the oxygen sensor and make the car run rich.

for the most part.. the modern computer cars have too low of a compression to benefit much from water..

if your combustion is low then you usually dont have detonation problems..

and if youve made enough mods to have high compression.. youve probably recalibrated your computer anyway.

by the way.. ken mentioned washer fluid.. yes this is the stuff to use.. just make sure it is Alchohol based and not windex..

kens system is the poor mans way.. which is certainly an easy way to get started... the second link i listed above is a nicer more performance oriented way to make your own system..

the preferred way is to install a "mist" sprayer.. this way the water instantly evaporates. when it evaporates it absorbs heat.

this can be very easy if you have an extra npt threaded vaccum port on your aftermarket intake.

it takes energy to change the state of matter.. (if i remember right.. it takes 288,000 btu to turn one ton of water @32F into one ton of ice@32F in one day.. (hence a one ton ac unit is 12K btu/hr) dont know exactly how many btu to convert water to steam, but it makes a significant difference.

also you want to have a ramped injection system for the water..

usually a throttle based valve actuation or variable pressure elctric pump, this gives you less water at an idle but cranks it up as your throttle opens.

for guys who have effective compression ratios of more than 12:1.. this setup ROCKS..

it is nearly essential in forced induction systems as forced induction loses most of its efficiency from heat. intercooling is the half step.. incooling + water is the right way.

you can build everything you need for a good setup for around a 100$


something else.... this thread is refreshing my memory of my old galaixe water system..

the first revision used a variable pump...

the second I modified it to actually suck the water back at no throttle and start pumping at above idle..

a rapid slow down would stall the car as too much water pressure was built up.


updated for clarification.

|UPDATED|8/2/2004 10:21:52 AM (AZT)|/UPDATED|

You're right Ben. Mine was the poor man's way. And it's never as good. But that was the point. Just another version. The best is still the best.

I pointed out the O2 for stock cars. Sometimes a bit of information is too much, or not enough. I don't want anyone trying a good idea to find it's a bad idea for their situation. Modified for performance is always a different ball of wax.

The factor of high compression seeing a greater benenfit is true. It will help. But even low compression non-computer cars will gain some advantages, if just to help keep the valves and combustion chamber clean. You may see very slight changes in fuel mileage with a low compression engine. Perhaps not. The small benefit may not be worth the effort.

There's that trial and error thing again. Kind of like a pink rabbit on a cross country trip.

It takes 970 BTU to turn one pound of water into one pound of steam. Or vice/versa. One BTU raised one pound of water one degree F.

|UPDATED|8/2/2004 9:28:10 AM (AZT)|/UPDATED|

kstyer said: You're right Ben. Mine was the poor man's way. And it's never as good. But that was the point. Just another version. The best is still the best. It takes 970 BTU to turn one pound of water into one pound of steam. Or vice/versa. One BTU raised one pound of water one degree F.

I was not trying to imply that it wouldnt work.. just trying show people the differnce in a simple and performance app..

thanks for the btu info..

how big of a water bottle are we talking about here? assuming we're trying to match a tank of gas with a bottle of water.
Ben, did your sytem run continuously or did you have an on/off switch?

as for bottle size.. many people use their windsheild washer bottle..

as for operation.. I used it continuously because I had my timing set ridiculously high.. the car wouldnt run without it.. I had a galaxie so storing a 5 gal water jug in the trunk wasnt a problem...

in theory the OPTIMAL way to set it up would be throttle sensitive with adjustable timing.

msd makes a box that will retard your timing.. use of one of these would allow you to adjust your timing on the fly (from inside the car).. so if you ran out of water.. the car would still run.

you set it high then use the box to retard your system back.. this would let you figure out the correct injection rate of the water for your car.

I would think a gallon of water/alchohol per 10 gal of fuel would be good in a high preformance app, 1/15th in a lightly modded street app.

while a simple water system will let your run your car with higher timing, produce more power, get better mileage, it takes tuning.. I personally think it is fun to tinker.. but youve got to want to do this as it could take weeks of tuning to find the perfect combination.

you could make a two stage fixed pressure sytem by RPM warning relays to turn on your system.. one set for 2K and one for 4K in a dual nozzle setup..

on a forced induction engine you would setup the nozzles based on boost.. for us normal aspiration guys.. we have to be a little more creative..

Mine looked like it was built by a 19 yr old poor college student. I used a switch from an electric train set and drilled a hole in the knob.. and connected it via a long piece of carb linkage to the throttle assembly. I used a cheap reversible variable electric pump..

doing it all over again i would modify the home made system in the second link above. it is much cleaner and hi-tech. or just buy a good prefab kit..

also I mentioned an extra vac port on intake. if you dont have one.. get a thin carb spacer and install your nozzles into it angled down.. ive seen people drill and tap holes in their intake.. this is a little to permanent for me.

|UPDATED|8/2/2004 4:45:09 PM (AZT)|/UPDATED|

any adverse effects on your exhaust sytem?

You could also put a micro switch on the throttle linkage and trip a solenoid when you reach a given throttle point. Two switches would make it two stage.

Won't hurt the exhaust at all. The water leaves with the exhaust. It's either steam or has broken down into different elements, and is no longer water. You get more water in the exhaust from condensation everytime you shut off the car and the system cools.

hank51 said: any adverse effects on your exhaust sytem?

none that i know of..

this is very popular on modern turbo cars.. in fact i belive I read that some turbo saabs have this from the factory now.

i know the water is ok.. I dont have any evidence to suggest that alchohol causes problems with a cat.. but like ken said.. if the car is modern... be careful..

you must beware of the consequences of using this with a computer car.

Up to 12% alchohol won't hurt anything. Goverment standards allow up to 12% blending. It is found in most, not all, gas sold in the country. If you get over 15% total you could start to cause fuel system damage.

so technically if we mix water and alchohol we are exceeding the government standard in a way and in a way we arent. assuming of course that there is already alchohol in the fuel.

since the water/alchohol mix never enters the fuel system.. ie tank, lines, pump, carb/injectors.. then this additional alchohol wouldnt affect the fuel system.

however.. what affect this would have on a cat? i dont know.