Here is a quote to put a damper on water injection
 

"The water injector is not a very interesting device. It has little place in a properly conceived turbo system. Two circumstances are viable for a water injector: a 1970 home-built Vega turbo with a draw-through carb, or a Roots supercharger sitting between a huge engine and two huger (really big) carburetors. To stake the margin of safety of a turbocharged engine on an inherently unreliable device is an idea whose time has long since passed. RIP. A water injector on a turbo car is a poor excuse band-aid for not doing the job correctly the first time."

MAXIMUM BOOST
Designing, Testing, and Installing Turbocharger systems
By Corky Bell

it is what it is, a cheap and easy way to turn pump gas into gas race

Let's get the full context. It sounds like he was talking about either replacing the intercooler with water injection or by relying on water injection to do all the cooling. I would agree in THAT context.

But to say that water injection has little place is a bit short-sighted. It DOES lower knock levels AND intake air temps. It also prevents carbon build-up in rotaries. These are all proven effects and are certainly beneficial.

I would not tune my car depending on the water injection but you can bet I'm going to run it as a safety net, especially with 91 octane gas. It's true that race gas would be a better solution but that is too expensive and not readily available. The last time I checked, distilled water was cheap and readily available. :)

I'm with Rynberg here, I been running a 50/50 mix for almoast 2 years now, BUT, my ECU was tunned for the amount of boost I was pushing at all times, so in case the W/I failed I was pretty safe anyway.

In the twins world we all know that when you push alot of boost there will be boost spikes, (I used to see sometimes spikes of 18psi while tunned for 14.7psi) HOT air pumping especialy in hot summers where apex seals may learn how to fly so easy W/I. is there to help prevent knock a bit and lower the intake charge temps.

You cannot relie on it and boost 20psi while you tunned for 16-17psi, but is a great additive to intake cooling, knock prevention and internal comb. cleanning.

Corky Bell wrote that book about 15 yrs ago and technology has advanced a lot since then especially in water injection applications. F-1 used it for yrs. in the turbo era. stop and think about the tech of rotory Mazda of 15 yrs. back and today big changes . thanks RON

Corky Bell's book is a great resource for gaining first time information on turbo systems. However, that book was written quite a few years back, and things have changed. I would argue that a properly designed water injection system could be as reliable as a fuel injector.

Rynberg hit it on the head. In the context of using WI to tune your car, and get more horsepower, you are taking a big gamble.

However, using it as an additional source to cool intake temps, is not a bad idea.

I have an aquamist 2s installed on my car, and I can actually see the intake temps dropping from the W/I.

With respect to technology. You should take a look at some of the offerings that Aquamist has. W/I systems have a come a long way.

As always, I have to post this link for a lot of "real" information on water injection.

http://www.aquamist.co.uk/phpBB2/

Water injection makes a great detonation deterant. With the nature of our rotary engines, I would think we want every bit of protection we can get. I for one am going to keep my water injection.

Adam

why would you even post this? did you not think at all?

I posted this thread as a gentle warning to those who are prone to jumping on the band wagon and twist the facts. It is for those masses that "don't think". In reading all the threads about WI, the device has been boasted way beyond what it is. It does not bullet proof a turbo engine and it is not a ticket to unlimited boost, which it is gradually being turned into.
I have nothing against WI, I just feel that someone should demystify the device befor it gets even worse.
The point is this, if you tune your car to the ragged edge where WI is a must, what happens if you run out of water in the middle of a run? On the other hand, if you tune the car properly within the safety marging, then why would you need WI? As someone had theorized, there might be a cleaning effectto reduce carbon build up, has that been proven? I could use gas detergents and achieve the same effect, which is in fact proven.
In uncountable threads, people have been preaching nothing beats proper tuning, but it seems that the misconception is getting deeper about WI can save your ass when your car is not tuned right.

The book was published in 1997, in case that's unclear, 2005-1997=8. And no, the technology has not advanced a lot. Water is water, you are still injecting water to prevent the chance of pre-ignition. To my knowledge water hasn't changed it's chemical property in the last 8 years. WI was invented to combat the lack of technology (fuel control), but with the advances in the fuel control technology and proper tuning WI is not really needed.

He is most likely talking about piston motors, not highly tuned rotaries that are pushing enough power to be on the knife's edge. If Water Injection saves one motor from a bad tank of gas then it is worth it. I don't think that quote is very applicable to any of us here at all.

i thought WI was invented in the ww2 era to cool intake charges on supercharged fighter planes.

anyway, i really don't think there are many rx7 people tuning their cars to the edge and then running WI, most people here run it as an intake charge cooler. i've never seen people actually tune for it around these parts. then again, since when is running an AFR of 10 the "proper" way to do anything. we all drown our engines with fuel to desperately keep them from blowing up. hardly the place to talk about general theory's of tuning engines.

the fact is, WI really is great. it lowers charge temps and helps against (not totally prevents) detonation.

what's next, a thread about how corky doesn't like the supra guys using a nitrous shot to spool their insanely huge turbos?

i mean, i understand your position now, and i agree that it shouldn't be relied upon. i just don't think a thread about it is justified.

When you tune your car safely and then run a W/I system you gain hp by lowering the intake temps even more after it passes thru the intercooler and in the process you get some added safety.

Please show any threads about people thinking this way, because I haven't seen any. It's not a miracle or cure-all, of course not. However, it IS added protection when added to a well-tuned car. I haven't seen anyone not treating it as such. If they have, naughty on them.

Fact is, Corky was wrong on this one..............

I read what Corky has to say about WI long ago. Some truth there, but I am sold on it for my purposes. I have used it in piston engines with small superchargers (Miatas). This setup should run without detonation w/o intercooler. 'SHOULD' does not take into account hot south Texas summers or hard driving in the mountains with only 90 or 91 octane 'premium' available. The water injection gives me the cushion that I need for safety.

I have spent the last year getting my FD in shape: new mazda reman, new twins, vacuum and fuel line repalcement and more. Finally finished last month. Guess what my next buy will be: water injection. Good insurance if you don't tune for it, and very cheap compared to almost any mod for the FD.

Tom

Yes, the water will reduce the intake temp, but don't forget when your are injecting water into the combustion chamber the water must displace certain amount of air, less air = less power. So if you are holding on to the hope of increased power from WI reducing the intake temp, think again. Here is a quote with dyno verification. If you are looking for power gains, you are better off spraying water on the intercooler.

Here you go:

Yep, water alone = power loss...but in the above example, I'd bet the farm that the engine was A LOT safer with it than without out. 5whp out of 409whp is barely a 1% loss. Where do I sign up?

If you are worried about power loss, mix it 50/50 with methanol.

I learned a hell of a lot from Maximum Boost, but it's getting to be an old book that:

1) Does not take into account the unique requirements of the rotary engine. Specifically, it has far lower tolerance to detonation than a typical piston engine. Detonation MUST be avoided in a rotary. It SHOULD be avoided in just about everything else.

2) Does not take into account the piss 91 octane gas that is available in many places now. Less octane = less resistance to detonation. See #1.

Even with my moderately modded car, I get increasingly nervous about pushing it on 91 octane. One of the guys that used to work at M2 works at local shop now (Modacar). He won't even consider driving an RX-7 on 91 octane.

Sonny

Don't get me wrong (apparantly that's what everyone is doing), I'm not arguing against the merit of water injection, I'm simplying using the quote to point out the fallacy that many people seem to be eager to believe.

I wrote a really long response to this, but then thought of a better way to put it.

YOUR STOOOOPID! J/K:rlaugh:

Seriously dude, check your facts. No one said it was panacea. And, I would be willing to bet my FD, my house, and my wife, that not a single soul on this forum has tuned for WI.

You guys should really spend some time on www.turbobuick.com or supraforums, there are many running 100-200 hp over what they normally make on 93 octane with LESS knock. Most rotary guys use it for safety and thus don't really tune for it -I would suggest searching the archives for threads from RICE RACING and others who have tuned for the water with outstanding results. People claim "well, if you lose the WI, you f*cked".....BS, there are so many safety devices available these days that you're more likely to kill the engine from a failed fuel injector before a properly setup WI system lets you down.

..my .02

I wouldnt run extra boost or lean out my AFRs with it. But, I would run it for insurance factor. I have seen a couple of posts here from people saying they tuned for 12.0:1 with over 1bar of boost and ran aquamist systems to keep things under controll. I think that is crazy. Personally, I dont like adding extra complexity to keep my car running. I dont like adding more points of failure either. If it is THAT important to have the most possible power from a setup I would have a street tune and a race gas tune and be done with it.

I agree with Bell in that a 'properly tuned" setup doesnt need it. However, it is not possible to tune for some dip sh*t gas man "accedentally" putting 89 in the 93 octane pump. That is where water injection comes in for us.

I believe that talking about Supras running it and making UBER power is irrelevant to us. I know Supras that run 30psi on street gas. That is way more pressure than 93 octane should ever be subjected too. It just so happens that Supras can take a ton of knock with out popping. We dont have that luxury.

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I talked to ray up at PF Supercars(great guy) and definitely knows his shit, I asked him about water injection, he basically said that water injection was just a way to prevent things that shouldnt happen if the car was properly worked on. I have not a clue, I plan on doing water injection(not tuned w/ it), just to see how it plays out!

This can and does happen---i have blown an engine (barely, 1 chipped seal) from a bad tank of gas here in NJ back in 2001. receipt said 93 octane, but upon draining the tank, the gas looked like shit. Thanks, exxon.

Rich

If you want to talk about myths and misconceptions, you can start with "water displacing the air, less air = less power". Think about how many CFM an FD engine will be running through it at wide open throttle at 8000 rpm; then think about how much water is actually injected even at that point. Basically, the amount of water injected compared to the amount of air ingested is so miniscule it's not even close to making a difference. If there was enough water injected to displace an amount of air that would have a significant impact on power, combustion would never take place.

The big myth is that WI cools the intake charge, resulting in more hp. All WI does is reduce combustion chamber temps, which is where the detonation protection for rotaries comes in. It does not cool the intake charge by evaporation and make it more dense (your intake temps would have to be super high for that to happen, and by that time you've got other problems); this is why you don't just bolt on WI and get instant hp.

Bell was referring to tuning very aggressively using only WI, which I agree is taking a risk. But using it as a safeguard without any real negative effects, or even tuning a little on the aggressive side to take advantage of its lower combustion chamber temps? I see no problem with that.

Precisely.

With properly sized turbos and intercooler, water injection is unnecessary. For people trying to push the stock twins on a 13B-REW too hard and get away with it...

......Snap Crackle and Pop :bigthumb:

I have a CoolingMist kit on my non-intercooled, centrifugally-supercharged FC. Currently, the intake filter is sucking in super hot air (up to 170 F, I have a thermometer next to the filter) from the engine bay, so that is not helping my ridiculous intake temps. My intake temp sensor is located just before the throttle body (about 12 inches from the water injection). Last Saturday, I drove the car around until the intake temps got to 179 F and did a pull from 20-90. The intake temps dropped to 138 F about 10 seconds after the pull and then began to rise again about 1 degree every few seconds.

Is the water injection doing anything? It's hard to say. With the intake temps so hot, the car is definitely down on power as opposed to when I first fire her up in the morning, allow the coolant temps to warm up, and then do the same pull; however, I like having the peace of mind that detonation will likely not occur. I've done no tuning for the water injection either; however, I am running stock timing with an S5 motor and 6 psi. My AFRs are probably ridiculously rich (got 11 MPG last tank), but for some reason, the dyno operator did not measure the AFRs when I made my 230 whp pull.

I haven't yet decided whether or not I'll install water injection on the FD. If it does nothing more than give me an extra layer of protection on an already well-tuned car, it certainly can't hurt.

Well put. Water goes in manifold as droplets, not molecules as in a vapor, so there is no phase change, and no significant change in charge air temp since the cold/hot mass ratio is very low ... like 1 to 50.

Although "1997" may show up in corky's book, his wi example quoted with Vegas and carburators suggests that part was written/conceived long ago.

I think it's great if done right, esp where 91 aki gas is all that is available. To tune specifically for it, you would need a water flow meter, and/or a knock interpreter for the PFC that could reduce danger if water inj stopped .. ie fuel or ign cut, etc.

here are some comments from somewhere out there...I did not correct spelling errors....you may notice some familiar names

What about the issue of running 50/50 mix with alcohol? I've heard of this being done but never have found out the details. Work better than straight H20? Are they referring to Methane?

"Methane" is a gas, not a liquid (unless highly compressed). "Methanol" is an alcohol compound used as a racing fuel. The only real reason to run a mix of water/alcohol is to prevent freezing in the water tank and lines; water has a higher heat absorption per weight than alcohol, so you're reducing the effectiveness by mixing alcohol.

agreed....I run water injection and it lowered my knock by 20 points during test runs. my knock never goes above twelve now and the car is tuned perfectly. my dyno sheets are a smoooooth.. so how u like them apples? intake temps are way down too.

I love them apples.

the only reason people are running WI on these forums is for safety. a bit of a backup to prevent pinging and losing a motor.

after going thru three motors, that feature gives me at least a little piece of mind.

you dont run out of water in the middle of a run unless you are retarded and forget to fill it when you fill your gas.

j

^LOL I was filling up with gas over the weekend, and realized this FD would be a b!tch to daily beat...Filling gas (93)...premixing...filling WI res...filling IC sprayer. I guess I should be glad I don't have to fill the oil or coolant too :shrug:

I looks like a goddamn garage sale when I go to fill up my gas tank. :p:

water injection is nice for the immediate result--reducing detonation.

but i like it because it keeps the combustion chambers clean for the LONG-TERM....carbon buildup = hot spots = boom.

I laugh really hard when I read quotes like that from Mr. Bell. I'll be more than happy to compare a good water injection system to the best intercooler he has to offer. The results will show the water injection based car will be able to run more boost, more timing, make more power have lower EGT's a steam cleaned engine and ambient or very close to ambient intake temps.

I have nothing against intercoolers but when a vendor bashes a product that threatens his own, its pretty obvious why.

To say that water injection is a band-aid, you would have to say that an intercooler is also.

In a perfect world you can say you dont need water injection, fine. But I can say two things for sure:

1) you are far more likely to detonate without water injection than with.

2) take a car and tune it with an intercooler get the max power you can out of it. Put a propery designed water injection kit on that car and you will make more power.


I cant count the number of emails from people that were pinging prior to having water injection with the after market intercooler and now can run 4-5 more lbs of boost and make alot more power with our system on it.

From reading through this thread, there are alot of other mis-conceptions. Alot of you think that a car cannot gain power from water injection without tuning and that is not true. We have seen time and time again that cars bolt our system on (and frankly our competitors kits also) and gain HP. It depends on the car. For example we found dodge SRT's are gaining atleast 18 HP to the wheels keeping the boost at the same level as without it. The SRT has a ECU that will advance the timing when there is no heatsoak. Or rather, it retards the timing when there is heatsoak. Because of this, they reclaim HP that would be lost otherwise. A car like the FD may not gain much HP from bolting it on because the computer in the car isn't going to automatically advance the timing to any great degree (the SRT's mentioned above were auto-advanceing more than 12-15 degrees). But in our tests at the drag strip we found that heatsoak is eliminated. Our trap speed remained constant throughout all the runs. Without the water injection it consistently drops throughout the day.

Also, powerloss with water injection typically means that too much water is injected or too much water at too low of a boost.

You're comparing apples to oranges; the SRT is "tuning" itself to adjust for the lack of heat. If you install WI on a car that cannot adjust its timing and fuel delivery very much (and was running fine before WI), you will gain very little (if any) power.

Again, if you want to talk about "misconceptions", you can start with the myth that WI lowers intake temps. It lowers the combustion chamber temps, not intake temps. If it lowered the intake temps, you would see horsepower gains just by installing WI, because the charge would be more dense (which is why installing an upgraded IC increases power to a small extent without any other mods). Your intake temp sensor is actually measuring the evaporation of water on the surface of the sensor due to the combination of the sensor body being heated by its surrounding area and the airflow over it.

I'm not saying that WI is a "band-aid" or is a waste of money (I think it has its merits), only pointing out some "misconceptions" here.

You mean "with" WI, not without.

Again, not taking any sides here, but there is a big difference between an IC and WI: the WI system has many components that-- if they fail (and yes, I know, the chances are slim...but it is there, even with the various "safeguards")-- could result in catastrophic engine failure if the engine is tuned aggressively.

The IC has no moving parts, and-- all aspects being equal with no changes-- will increase power just by its installation.

BY the way, full alky cars, no gasoline, run no intercooler at all just big injectors. something to think about, as if we didnt have enough now, this stuff goes on forever, but thats what hot rodding is about, got to love it! RON

That's because they only have to run a couple of minutes (burnout, staging, run), and their fuel delivery amount is so huge (gallons per second) that there's no chance (well, mistakes often happen, resulting in blown engines that get fixed/replaced before the next run) for detonation to occur.

Another point, what is a properly designed setup? He is most likely talking about racing setups.

I bet that when running over 16PSI boost, his proper setup IS USING very high octane racing fuel. In that case he is correct. But how many of us can afford to run that all the time or even can get it.

What context was it ment to be interperted in?

I think if you read my post you will see I said that

I think if you read my post you will see I said that (eg, the rx7)
Everyone knows that water injection lowers the combustion temps, thats the point. If you want to dis-agree that it lowers intake temps feel free. I can tell you that the stock and aftermarket sensors not only are significantly lower with WI, if you stop spraying the water they stay lower for quite a while before heating back up again.

Nowhere did I say that water injection is as reliable as an intercooler. its not.

Im aware that an intercooler increases HP in a car, thats not indispute. Take that same car with the intercooler and most likely you will be able to run more boost, timing and make alot more power if you put water injection on it.

Im not making this a WI vs Intercooler debate. I believe if your car came with an intercooler from the factory you should not remove it, because as pointed out its reliable. I believe you should run water injection with it.

Yes, and that's what we're talking about here on this forum, not Dodge SRTs.
What point? You never mentioned combustion chamber temps in any of your posts here in this thread. All you mentioned were intake temps. There is a big difference.
If you read my post again about the sensor reacting to water evaporating on its surface, you'll understand why the "stock and aftermarket sensors stay lower for quite a while before heating back up"-- residual water droplets don't immediately evaporate in the intake tract, and that's why WI does not cool the intake charge.

Kento:

It's been proven countless times (on 2 of my own cars no less) that water injection dramatically lowers intake temps...to the tune of up to 100 degrees. Now, in both of those situations, I had a roots blower with no I/C. For a lot of roots-based systems, WI is the only practical solution because the blower exit is often only inches away from the intake valve.

If your assertion is that WI is less effective on a system with proper intercooling?

Sonny

No, I'm not saying that WI is any more or less effective, just pointing out some misconceptions, including yours stating that "it has been proven countless times". Please read my posts on why the intake temp sensors indicate lower temps with WI. If it was "proven", then you would see a HP increase just by installing WI with no other changes.

As stated before, I believe that WI has plenty of merits, including applications like the Roots-type blower you speak of (although many OEMs use a liquid-cooled IC in those applications, due to the aforementioned reliability reasons).

Someone, I dont recall who said in one of these posts that water injection does NOT increase power, you have to tune for it. They did not mention RX-7's. They simply made a blanket statement. This thread was not about rx-7's, but about Mr. Bell's irrational fear of water injection.

there are alot of things I did not mention. Does that mean I dont believe it? Do I have to mention all of my beliefs in my posts?

Again, I disagree with you. I can tell you that when I stand in line at MGM in southern cali where the misting systems are on a 100 degree day it actually gets chilly when its scortching hot outside. I see how the intake temp sensors react and for what its worth, the water injection is WELL before my intake temp sensor.

You are entitled to your opinion.