Trexthe3rd

"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

BoostFrenzy

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

rynberg

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.

TwinTurbo93

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.

ronbros3

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

Goodbar6

iTrader: (1)

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.

Jesuscookies

iTrader: (1)

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/

fastcarfreak

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

particleeffect

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

Trexthe3rd

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 *** 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.

GoodfellaFD3S

iTrader: (213)

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.

particleeffect

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.

SilvioRX7

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.

rynberg

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.

Marshall

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

miatrx

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

Trexthe3rd

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.

Trexthe3rd

Here you go:

Sonny

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 **** 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

Trexthe3rd

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.

Jesuscookies

iTrader: (1)

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

YOUR STOOOOPID! J/K

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.

Marshall

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

855m0n0

iTrader: (1)

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.

Tenacious

I talked to ray up at PF Supercars(great guy) and definitely knows his ****, 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!

GoodfellaFD3S

iTrader: (213)

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 ****. Thanks, exxon.

Rich