[AZSTI]

I just wanted to give my experience with the water injection kit that I installed. I live in Arizona and recently it has been getting very hot, I believe it was 114 today. It's been the first time that I can really test my water injection system to see if it really helps. The last two years I had noticed that anytime it was over 100 degrees the engine would start to ping under a decent load and when psi went above 10. I didn't know the extent of the issue until I had installed a boost gauge. I noticed that if the engine pinged enough, the ECU would drop pressure to limp mode, so the max psi I could achieve would be about 7psi. I was pissed because Subaru would not do a thing about it and basically would just reset the ecu if I had brought it in. Although resetting the ECU would bring the boost levels back to stock, it would go right back to limp mode if I put a high load on the engine. I knew I had to do something else to fix the issue and water injection seemed to be the answer. Well I can now say that it works great, I have not heard my engine ping once, no more need to buy 100 octane gas (not that I could afford it now) . So if any of you experience the pinging, my recommendation to you is to just spend the money and install a water injection kit.

[Deuce Cam]

Did you have the car tuned after installing the wi? If so, was the wi tuned for just a safeguard or did you use it to make more power as well?

This is interesting to me because I live in the same place as you and have similar problems. My car will sometimes ping a little at wot on straight 91 when the weather is like this. I usually mix about 4-5 gallons of 100 in the tank during the summer which gets rid of the pinging for the most part (luckily I'm not dd my car at the moment). Even with the mix I still try to avoid going WOT when the temps are above 100-105.

Are you aware of any negatives to running wi? Can the water cause harm to engine components over time? I'm a newb on the subject....

[AZSTI]

I'm by no means an expert on this, but I have read quite a few articles regarding WI. My application was purely to keep the car from pinging, I am sure that I could tune it and turn more boost out of it, but I have not had the time to invest in that yet. From what I have read, water injection is very safe especially if you are not increasing boost. If I ran out of water in the tank, it's no big deal I just try not to get on it too much when it is empty, if I do wot, then the worst thing that could happen would be some pinging given the temp outside. I believe the system is somewhat good for your engine as it kind of steam cleans the engine in a sense. During the winter months, I tweak the boost pressure switch to go off at a higher boost level. I've heard people say that it can bog down the engine but I have not experienced that. In a way I believe it effectively rasises the octane of the 91 that I put in there. I use to do the same thing with putting 100 octane in every now and then, it proved to be a big pain in the ass plus it cost too much, and so far from what I can tell it gives the same if not better results. To me it only made sense, intake temp is way too high in the summer, even with the intercooler, why not mist some water near the throttle body causing the charge air temp to be drastically reduced. I drilled a hole into the intercooler just before the throttle body, seems to have worked very well.

[PhantomSTi]

Originally Posted by AZSTI

I'm by no means an expert on this, but I have read quite a few articles regarding WI. My application was purely to keep the car from pinging, I am sure that I could tune it and turn more boost out of it, but I have not had the time to invest in that yet. From what I have read, water injection is very safe especially if you are not increasing boost. If I ran out of water in the tank, it's no big deal I just try not to get on it too much when it is empty, if I do wot, then the worst thing that could happen would be some pinging given the temp outside. I believe the system is somewhat good for your engine as it kind of steam cleans the engine in a sense. During the winter months, I tweak the boost pressure switch to go off at a higher boost level. I've heard people say that it can bog down the engine but I have not experienced that. In a way I believe it effectively rasises the octane of the 91 that I put in there. I use to do the same thing with putting 100 octane in every now and then, it proved to be a big pain in the ass plus it cost too much, and so far from what I can tell it gives the same if not better results. To me it only made sense, intake temp is way too high in the summer, even with the intercooler, why not mist some water near the throttle body causing the charge air temp to be drastically reduced. I drilled a hole into the intercooler just before the throttle body, seems to have worked very well.

I can chime in a little bit.. Meth is what raises the octane rating, where as the water (If you run Water and Meth) cools the charged air. You should purchase a Spec C tank for your WI kit AZSTI, I haven't had to fill up my Spec C tank in about 5 months now from running 50/50 Water/Meth of course, I had to dump 3 gallons worth of it in there.

[halfelite]

You can run just water without a tune and the stock map will learn on it to an extent to help but by no means as good as a tune

[Neanderthal Racing]

Originally Posted by PhantomSTi

I can chime in a little bit.. Meth is what raises the octane rating, where as the water (If you run Water and Meth) cools the charged air.

that really isn't so. neither water injection nor meth change the octane rating. by cooling the charge with either or both in tandem, you can tune as if you changed the octane rating. meth has better evaporative properties than water, with a 50/50 split proving the maximum effect as i understand it. please note the sloping forehead.

[fullerton]

Originally Posted by Neanderthal Racing

that really isn't so. neither water injection nor meth change the octane rating. by cooling the charge with either or both in tandem, you can tune as if you changed the octane rating. meth has better evaporative properties than water, with a 50/50 split proving the maximum effect as i understand it. please note the sloping forehead.

I would go a step further and say that water does indeed change the octane rating in addition to cooling the intake charge. EDIT It looks like the change is not large enough to make a difference. The real benefit is the reduction of intake charge temp.


However, I would not be running any type of secondary injection without a tune.

[Tortfeasor STi]

Originally Posted by fullerton

However, I would not be running any type of secondary injection without a tune.

I agree with this sentiment. I would not run any major engine modification without a proper tune. Too many things car go wrong in an expensive way. I find a few hundred on a tune is cheap insurance for a 6K engine.

As far as octane ratings, it does not affect them. What it does affect is the temperature of the charge going into the engine. Whether it be chemical cooling with meth or alcohol or water cooling, what you are doing is cooling the engine/charge air. Regardless though, it does not matter as what you are doing is the same, moving your engine out of detonation range. Range being defined as the temperature and pressure of a given air charge that when ingested by the engine will yield pre-ignition or pinging.

[PhantomSTi]

Originally Posted by Tortfeasor STi

I agree with this sentiment. I would not run any major engine modification without a proper tune. Too many things car go wrong in an expensive way. I find a few hundred on a tune is cheap insurance for a 6K engine.

As far as octane ratings, it does not affect them. What it does affect is the temperature of the charge going into the engine. Whether it be chemical cooling with meth or alcohol or water cooling, what you are doing is cooling the engine/charge air. Regardless though, it does not matter as what you are doing is the same, moving your engine out of detonation range. Range being defined as the temperature and pressure of a given air charge that when ingested by the engine will yield pre-ignition or pinging.

Thanks for clarifying guys

[Flycaster]

Originally Posted by fullerton

I would go a step further and say that water does indeed change the octane rating in addition to cooling the intake charge. EDIT It looks like the change is not large enough to make a difference. The real benefit is the reduction of intake charge temp...

Right on. Water, by defintion, has zero octane so it does decrease the effective overall octane of the final combustion mixture, however the heat loss more than compensates for it. Meth, otoh, has an octane rating higher than racing fuel, so if used by itself, it does increase the effective overall octane of the final combustion mixture, in addition to providing a cooling benefit (although not as much as straight h20).

As stated previously, the general consensus is that a 50-50 mix provides the best overall benefit of increased performance, coupled with safety (this assumes, of course, that the system never fails). Nonetheless, guys looking for the most gains will get them using straight meth.

Tuning for either takes a lot of knowledge. You can run water injection untuned. It won't hurt anything, but you will leave a lot of safe power on the table if you don't get tuned for it. [edit] In fact, with no tune, you will actually loose some power under ordinary conditons (ie, not 114* ambient temps)

[Neanderthal Racing]

i need to keep up with my c.e.u. s (isfh)

[gabedude]

The octane rating is changed by the methanol content. Why do you think they add 10% ethanol as a knock inhibitor to raise the octane on 91/93 octane gasoline? What do you think is raising the octane rating? Magic?

Yes, 50/50 Meth is better than race gas IMHO.