I dont see the point of the switch. The kits come with something that lets you set the psi at which the pump engages. As your manifold absolute pressure rises your intake temps should also be rising along with them(they should correlate). IE at say 5psi you should always have approximately the same resulting temperature from the gas compression. So if you determine what psi your intercooler can no longer cool well enough then you know when you need the pump to be on.

thanks for the reply.

thing is tho, is that i was hoping to get by without having to buy a WI kit. i figure i can knock something up on the cheap and save myself a bunch of cash.

for example, i'm thinking i could build something using the switch i mentioned, the standard windscreen washer water bottle and pump, and a spare fuel injector (i'm upgrading my injectors so i'll have 4 spare). know what i mean?

the fuel injector will rust over, and the windshield washer pump does not have enough pressure to properly atomize the water. The base devils own WI kit is only $180 through wideopentuning's group buy. You wont find a less expensive water injection kit of that quality. Its 110% worth the money.

ok, thanks for the info. i'll check into this group buy but still interested to see if this other idea is worth pursuing.

fatty, i just picked up a nozzle, piping, and a 60psi pump, and a adjustable boost switch for 50 bucks on e-bay. I think the WI+intercooler with the temp switch is a great idea, was actualy thinging about it myself..

Perhaps some general info on living with a WI setup would be helpful. At least, for a WI virgin such as myself.

For example, where can a person buy methanol? How much does it cost? And at "reasonable" levels of boost and HP, how many miles do you get from a (quart/liter/gallon, etc) of meth at whatever concentration you mix at? Assume a lead-footed driver who drives 75% city, 25% highway, making maybe 200 HP.

If one were to use the stock washer bottle as a tank, would the 15-20% blend still be suitable for an occasional window washing? Or will this simply destroy the paint, rubber, etc?

I always just use washer fluid. Its very easily obtainable, you can still use the stock reservoir and clean your windows, It hardly effects your a/f at all. The Supertech blue stuff from Walmart is popular. I guess its around 25% methanol.
Topping up with about a gallon each time you fill the tank is about right if you have a lead foot.
Some of the pumps on Ebay don't have the upgraded seals to live with methanol on a regular basis. Just something to remember.

The usage will vary depending on you nozzle size and pressure at 176cc min you will use 10.56 liters an hour aproximately the typical install has 2 liters or abit more on the supplied tank. The washer tanks we use are about the same size but you would need to find a way to mount the pump under the hood the simplest way is to put it in the trunk. a 15-20% mix shouldnt be very bad for your paint but i wouldnt wash my car with it.

BTW i could use 2 quarts in about 25 minutes covering about 30 miles. on my way to work only 5 miles of highway go figure. :)

You consume that much just driving normally?

i have a lead foot. gallon a day keeps the doctor away. normal Speed limit here is 55 i travel through about 3 miles of 35 and about 6 miles of cop terotory give or take on the cops.

How about nozzle location? before the intercooler, after the intercooler, just before the throttle body, before the turbo.. just after the turbo?

Just before the tb here is a pic.

i was reading an article where a guy put it before the turbo, that seemed like it would damage the turbo to me, anyone heard of this.. and is there any advantage to putting it at the throttle body rather than somewhere else?

A general idea is that if you inject earlier in the air stream you let the water absorb maximum heat. I am not sure if there would be any signifcant different injecting just after the intercooler vs just before the t body. On the S4 install I did I went just after the outlet on each intercooler. On the SRT-4 I went about a foot away from the throttle body. Good results both times. I think on my Gti I just bought I will do it right at the intercooler outlet as well. I would prefer to have it all out of sight.

anywhere from 6"-10" from the throttle body is best w/ no pipe bends inbetween. One problem i see from putting it too far away from the throttle body is that it will allow some of the droplets to pool up.

Also, contrary to what most people believe about WI cooling the charge, there are some published journals that suggest that the droplets are suspended for such a short time that lowering of charge temp is minimal, and close to zilch. What people are seeing as cooled intake charge is actually the droplets collecting around the iat sensor and evaporating off.

Furthermore, the studies suggest that the droplets accumulate on the internal combustion chamber walls, and b/c h20 has a high latency of evaporation, when it turns to steam some of that energy as heat is taken with it. The alky is just burned up and slightly increases octane.

I think one reason why it hasn't really cought on is b/c of the availibility of more advanced fuel mangement for imports, b/c obviously you won't realize much gains without tuning for the WI. In the Honda world, in the last couple of years, ECU tuning technology has advanced in leaps and bounds so more and more people are catching on. As far as i could tell i think i was the first Honda guy to use Devils Own kit. No offense to the Miata community but its discouraging when i look at whats readily available for tuning Miatas, unless you go full stand alone.

Just another food for thought, since the h20 is now used for thermal management, you can run a/fs 12-12.5 where flame front speed is faster and most torque is made, also requiring minimal ignition advance.

On my car i run The Devil's Own progressive kit w/ 5gph nozzle (about 360cc) and 25psi of boost on 92pump.

You run that on your miata or your honda? yeah i know all about my decreased bsfc. i have no ait so all my obsevations are just on what i can see and feel. Feels good looks good no problem. Water or fuel doesnt like to make turns the further it has ot travel the more likely it is to pool in your intake you want the WI medium ot stya suspended asit enters the Combustion chamber

All my WI experiences are done on my Honda. The bottom line is you won't be able to tune for MBTT with out the aid of at least a wideband to get you in close proximity of effective a/f ratios, hence the "feels good looks good no problems" isn't really saying much.

Works so far till it stops being effective ill keep it up when it ends up being unnafective i will probably get a wb02