Water injection?

Anyone care to explain this to me and please, go in some detail. I heard this term today and couldn't make any sense of it.
if its Lt1 tech, shoot it over there. no offence will be taken, but I might burn down your house and steal your car :)

Originally posted by treyZ28
Anyone care to explain this to me and please, go in some detail. I heard this term today and couldn't make any sense of it.
if its Lt1 tech, shoot it over there. no offence will be taken, but I might burn down your house and steal your car :)

Usually related to force inducted cars. Ive heard of people using water/alky or just straight alky injection but have never heard of anybody just using straight water injection. What the alky/water injection does in a nut shell lower your iat's and the alky acts as a octain booster and helps fight detonation. The turbo buick guys have pretty much perfected this setup on there car and have since then for the most part have switched over to propain injection. What it allows you to do is run more boost or add more timing without the risk detonation. The alky also cleans all the carbon off the pistons as well. All in all its a pretty usefull aid for force inducted cars. :)

there's a guy at UF who can run 25psi on pump gas with an alky injection kit on his dsm.

I have never heard of water injection on cars, but on pulling tractors that you see at the fairgrounds. I talked to a guy who has a tractor and he said the water injection is to only way to keem em cool. If you ever watched, when they are at the starting line they are rolling off a lot of black smoke and then it turns white right before the run...well that's the water injection. He said they burn 3/4 gallon of fuel and 1 gallon of water per run. but I have never heard of it in cars though. It might have been done before.

if youre going to use an injection method to cool air-intake temps, i would not bother with the water/alky mix.


it works great, but from what people tell me, its a pain to have to fill it up all the time, cause you go through it very fast.


thats why the buick guys are switching ti propane injection.

it significantly lowers intake temps

it also increase octane, usually over 100. (mmmm.....daily driving with 100+ octane......hehehe)

tank is VERY cheap to fill, and lasts a LONG time.


i dont see any reason why you couldnt use it on an n/a car, but i dont think youd see much benefit like the f/i cars do.

rskrause uses water injection....Im sure he could chime in with a good explaination as to why he used it.

Water is primarily used with forced induction, though it may also have a role with NA this is less well defined. The primary effect of a water/alcohol misture like I use is to cool the intake charge, but is also has beneficial effects on combustion. It boths slows combustion (equivalent to increasing octane) and by producing reactive free radicals leads to more complete combustion (and hence more hp).

Intake cooling is a consequence of the high heat of vaporization of water and alcohol. Water has a higher heat of vaporization than alcohol. But is still considered advantageous to add alcohol. I have verified that it helps and found that a 1/3-1/4 mixture of alcohol/water seems to work best, though I am not sure why. Alcohol will help prevent any freezing of the mixture, if you car is exposed to sub-freezing temps.

Anyone who doubts these cooling effects should look at an alcohol fueled car at the track. A buddy of mine runs on blown alcohol Hemi car. When he is warming it up in the pits on a hot summer day ice will form on the "hat" as water vapor in the ambient air freezes on contact. Even at the end of a run, the hat is cold to the touch.

Rich Krause

Originally posted by 4th-gen-formula
I have never heard of water injection on cars, but on pulling tractors that you see at the fairgrounds. I talked to a guy who has a tractor and he said the water injection is to only way to keem em cool. If you ever watched, when they are at the starting line they are rolling off a lot of black smoke and then it turns white right before the run...well that's the water injection. He said they burn 3/4 gallon of fuel and 1 gallon of water per run. but I have never heard of it in cars though. It might have been done before.

Ask the guy if he is also using the WI into the turbo turbine area. This would be used to help spool up times. This may account for some of the additional white exhaust. As far as the WI in the chambers is concerned, if he is using as much as 70% water to fuel (mass not volume) or more, use this as a 'grain of salt' if contemplating WI in an engine that will actually see 'miles' for street use. Although using 70% water to fuel (by mass) has shown additional gains over lesser amounts, these over 50%, (by volume) 'concoctions', may not be 'engine longevity friendly'. IOW, experiment at one's own risk. :)

Arnie: my math isn't great. But I was thinking about mass/volume. With my setup, assuming that under boost I am actually delivering ~12gph of water and my BFSC is 0.50 I get the following.

12gph = ~100lb/h of water
~850hp = 425lb/h of fuel

On that basis, the mass of water injected is ~25%. If I go much larger on my infection nozzle, the motor lays down. So how do they get >50% to work?

Another note about "water works". After two years of operation, we tore my motor down this year and saw no evidence of detonation. 8.5:1CR, 14pis, 150hp nitrous shot and no intercooler. So, it does work.

Rich Krause

Hey Rich...... I use 8.34 lbs./gal. for water and 6.18 lbs./gal. for gas. That equates to gas having a SP. Gr. of .74..... Course SP Gr. of gas will vary, depending on whom you talk too. :) But, looks like we are pretty close.

Originally posted by rskrause
On that basis, the mass of water injected is ~25%. If I go much larger on my infection nozzle, the motor lays down. So how do they get >50% to work?

To be honest.... shrug. Well, you can definately lean out the mixture when using more water. How that fits in with your senario, don't know. THEORECTICALLY, (ie, according to injineers) ah, sorry Fred, 70% is the most water that can be vaporized by TDC with an effective CR of at least 9 to 1. The water will actually lower peak pressure, (and temp) in the engine. Also, the 70% (of fuel mass) ratio is used in reference to the theoretical stoich A/F ratio. 'Cuz water has a cooling effect, running richer than stoich means using less water, because using more fuel by itself, also has a cooling effect. This obviously applies visa versa, meaning more water, less fuel. I have a way of confusing things. :)

Another note about "water works". After two years of operation, we tore my motor down this year and saw no evidence of detonation. 8.5:1CR, 14pis, 150hp nitrous shot and no intercooler. So, it does work.

Yes, no detonation, but when we are talking 70% (of fuel mass) which, according to my calcs, amounts to over half water, (by volume) I'm more concerned with durability/longevity (or lack thereof) of engine package upon teardown.

Most of the serious GN guys run alcohol/water injection systems. It's simplicity and sucess is unsurpassed (maybe except for N2O). The water vapor metered properly produces steam, raises the dynamic CR, but at the same time lessens the octane requirements of the engine and keeps everything clean in the process (i.e. removes carbon off of head and piston tops, thus reducing the possibility of detonation due to carbon build-up. I have played around with alcohol/water injection (a very simple atomizer) and with a G-Tech used as feedback, can testify that it works very well even as a stand alone power adder...
Just go to the GN site and read a little. It definately does work as stated...

So where into the intake side of the motor is the H2O or alky injected?? Just curious.

Originally posted by sb427f-car
So where into the intake side of the motor is the H2O or alky injected?? Just curious.

About 18" in front of the throttle body into the intake tubing.

Rich Krause

I just got my SMC alky kit for my GN yesterday. I hope to have it in the car in the next few weeks.

If you want info on alky....check out www.turbobuick.com and go to the alcohol forum and do a search. Tons of stuff in there.