Node

iTrader: (1)

We all know that the stock intercooler sucks, especially over 12psi.
Water injection seems like a good bandaid and can also be used with an FMIC.
You can put together a makeshift kit for about $100, pumps are about $40, boost switch is like $10, then get a tank, some hose and a nozzle of some sort.

Then of course there are the manufactured kits like aquamist and numerous others. But I'm a cheapass, and my friend has made his own kit so I can get any help I might need from him when it comes to nozzle size and wiring.

Not sure on nozzle size, will have to do some research in the single turbo/3rd gen forums to find out what to do. Believe I have some good info from RICE RAcing somewhere on my computer.
And of course, wether to run all water or 50/50 water/alcohol. The alcohol will bring down your intake temps a ton, I have watched my friends FD drop intake temps by 25-30 degrees celcius from aa few short runs of boosting. But his nozzle was a bit oversized so once off boost it would bog down and stutter, but still that shows the cooling abilities of alcohol. I believe alcohol lowers the octane slightly so that should be taken into consideration also.

However single psi systems like I'm talking about are flawed. Aquamist is by far superior whereas it uses the injector pulse to control its flow. Now to just figure a way to rig that up. Maybe an Additional Injector Controller would do the trick, then just size up a proper injector and run the single line directly to the injector, but then would you have to figure out a fuel pressure regulator? As the pump I'm looking at is 60psi and stock fuel is about 40psi I believe.



Well, was just doing some thinking, and thought I'd share my thoughts and see if anyone has any experience or input. Any is welcome.

-Ben Martin

Node

iTrader: (1)

bump, no one?

T2monster

SMC alcohol injection. Good stuff, buddy has it on the GN.

http://www.smcenterprises.com/

Node

iTrader: (1)

niiiiiiiiiiiiiiiiiiice, but im going cheap. heh. still wondering what ill use for a tank

RX-Heven

iTrader: (1)

I have an aqamist system with a front mount if you want some info.
I'm running two .8 mm nozzles right now and will be bumping them up to two 1.0 mm nozzles next time tuning.
I'm only running 10 psi right now but I have 10:4 (series 4 TII) rotors and 91 octane.
I talked to a aquamist rep from some midwest Saab place and what he said which has also been backed up by others to tune your car without the water injection first with as much boost as you think is safe, then inject just enough water to make it cut/bog out. Then start to turn the boost up and correct the afr from there.
Repeat process.

I'm in the middle of this process currently and am learning along the way...hopefully not learning the hard way

Also, make sure you wire the injector pulses from the primary injectors as these will see 100% duty cylce or thereabouts, certainly more than the secondaries. But if you do this, you will need to have a pressure signal to fire the water injectors as you obviously do not want them on all the time.

I am still unsure on this, but I believe water cools better that alcohol.

You can use anything for a tank, even an overflow tank such as an NHRA approved 1 liter soda bottle.

Node

iTrader: (1)

i was just gonna use it untuned, because of the horrible stock mount, and sort of as a precaution, more for the temps than detonation protection, but its a nice sideeffect.
is it a dual stage system?

Wankel7

Sounds like a good setup and good info!

How did you get your S4 TII rotors to a 10.4:1 compression... is that what you ment?

Node

iTrader: (1)

lol yeah, i just sorta tried to ignore that. i make enough smartass comments as it is.

Wankel7

Yeah, I really had a hard on to do the aquamist setup with the TMIC .

However, I got a killer deal on a Greddy Fmic / HKS bov

However, after I recoup savings....Aquamist is a thought!

James

ShadowX

Just be careful with a custom setup. Cheap parts tend to leak after a while and it's hard to get a high pressure pump that is both reliable and cheap. On that note, I'd love to go with water injection to, simply for reliability, no performance increase. Please keep us updated. I may follow in you footsteps!

vicious525E

not to mention it will help prevent carbon build up

Node

iTrader: (1)

well, my friends had his pump as long as ive known him and runs it on his daily driver all the time (FD). and the only time the pump ever failed was because he tried running 50/50 water alcohol and the pump seals where not made for alcohol.
so we found a local supplier for that pump and since it was close to my work i went and picked it up on lunch, turns out that the owner of the pump company has a 10AE

and the parts are not cheap, theyre just not overpriced in a kit, and its very simple.
Tank, hose, Pump, pump switch, solenoid.
Pump can be had for like $40, same one suggested for most DIY water injection, the 60psi/100psi pump.


I was thinking just inject on the TB elbow, that way it doesnt fall into the turbo, or maybe in the IC endtank above the throttlebody, give it a little more time to atomize and spread up, you don't want an uneven spray, may create a "lean" condition of some sort

-Ben Martin

I will grab part numbers and links tomorrow hopefully

coolingmist

For nozzle size just look at the formula

(Total CC's of fuel * .016) * max injector duty cycle you plan to run ) That will convert your CC's of fuel to Gallons per hour. From there you figure 10-18 pct water to fuel you want with your injectors. So take my rx7 for example

2 injectors * 1200 cc =2400 CC's of fuel.
2 injectors * 550cc=1100 CC
totall of 3500 CC's of fuel.

thats 56 gallons per hour I find myself at 80 pct duty cycle so thats about 45 GPH at 80 pct.

With that I would get myself a 4.9 injector. Generally you want to be from 10-18 pct. It gives you a good place to start, but you may find from tuning you have too much or not enough water.

We have been given permission from jason to run a group buy and if there is enough interest will do so.

https://www.rx7club.com/showthread.p...19#post3989719

Kenteth

take a vac line up to inside the cabin, everytime you start to boost just pull the trigger of your waterfilled windex bottole into the vac line and,...

RX-Heven

iTrader: (1)

Oops, I meant series 4 na rotors in my TII engine. The engine build is a Frankenstein build up of what was available pretty much.

RX-Heven

iTrader: (1)

Single stage system:
Aquamist 2d
http://www.aquamist.co.uk/cp/806-009/806-009.html

Wankel7

Its all good....I was wondering because I am putting S4 rotors in my S5 TII...I was like....did I miss something

That is cool you are going with the higher compression rotors....I hope you make good power with it!

James

turbo80cid

have you looked at a company called Boost Cooler?
I don't know how much$ but you might want to check it out.

I'm planing on some type of water injection with the top mount sometime in the near future.

Good luck

YearsOfDecay

Controlling detonation is the ONLY reason for installing water injection... Its main function is to reduce the combustion chamber temperatures.

Its a common misconception that the water reduces the intake temperatures... it really does't reduce the intake charge temperature very much... not enough time before it enters the cylinder... People who have installed an intake temperature probe AFTER their water injection always claim that they see a HUGE drop in intake temperatures after the water injection kicks on... what they are actually seeing is, in large part, the effect of the water mist evaporating on the end of the probe, thus producing a cooling effect on the probe... (unfortunately, there is no way to accurately measure the air charge temp drop without getting the evaporation effect on the probe, you could put a 180 degree shield on the probe, but the vortex effect would create a negative pressure zone at the edges of the shield and knock the water out of suspension and interefere with the probe anyway) it does evaportate in the air, but to a much lesser extenet that on a solid metal part, a few degrees at most the temperatures are not high enough (well, if you are seeing 300 degrees after the stock TMIC.. Maybe!!!). BUT.... You really don't want it to evaporate in the intake system and here's why:

The biggest benifit of the water injection is that when the water mist hits the cylinder walls (rotor housings) it instantantly evaporates into superheated steam, thus cooling the interior surfaces of the combustion chamber, hopefully to the extent to avoid pre-ignition of the compressed air charge by the hot internal parts...

Also.. as the air charge gets compressed, the temperature rises, and the remaining water suspended in the fuel charge will evaporate after the fuel, again lowering the charge temperature, and reducing the chance of detonation. The water acts as a buffer in the charge to prevent to rapid a rise in temperature caused by the compression of the charge by the rotor (or piston if you are one of those people). So you want it to remain suspended for as long as possible.

Water injection is viable.. it works... however, it should be used in combination with a good intercooler... what happenes if you run out of water and the water injection is you biggest source of detonation prevention? I know you dont have money falling out your ***... if you did, you'd have a third gen!!!! But be cautious as you step into this area.

Make sure you put a wideband on it as well, water displaces fuel and air... if you don't have enough fuel... all the water in the world isn't going to help you.

edmcguirk

Those are correct and excellent points but there are a few other important points as well.

The water vapor acts like an inert gas inside the the combustion chamber which helps prevent detonation (similar to EGR). It slows down the combustion process so the peak pressure is lower but it lasts longer. A proper setup should also advance the spark during water injection so that the peak combustion chamber pressure occurs at about 17 degrees ATDC.

There is some evidence that the water vapor also acts like a catalyst in the combustion process (I know that seems to contradict the last paragraph)

Mixing alchohol in the water is only a benefit as an octane booster. If you have good enough fuel you shouldn't be adding extra fuel that the ECU is unaware of. Pure distilled water works best. But if you need the octane boost, go for it.

Water injection will change the readings on a wide band oxygen sensor. Rich mixtures will appear not so rich and lean mixtures will appear not so lean. Be careful!

Water injection works best as an integral part of your fuel system. If you lose the water, stop the boost! If you use it as a bandaid or a safety valve you are wasting at least half of its benefits.

ed

RX-Heven

iTrader: (1)

Alcohol will also prevent the water from freezing causing pump failure and/or split lines.
A 50/50 mix is the max ratio that you may want to use, that is at least what Aquamist has recomended.
More than that, you should just use an alcohol specific injection system.
A friend of mine used it in his Buick Grand National powered 2nd gen with great success.

Node

iTrader: (1)

definately some good reading, but what i meant about lowering temps, was with alcohol. i never really noticed intake temp diffs on my friends FD w/ PFC from water alone, only w/ 50/50 water alcohol

edmcguirk

A majority of the cooling happens inside the combustion chamber as the pressure rises. By TDC all the water is vaporized. Alchohol is more volatile so you would see early drops in temperature but water has a higher heat content so it catches up and surpasses the alchohol contribution by a large margin.

ed