sudseh

I don't mean to start a flamewar, only some thoughtful discussion since only the pro-h2o injection view has been stated.
that said.

firstly; water injection is not bad, just not needed in the modern fi world for anything more than a safety net.

IMHO ... a turbo engine with properly designed intake/exhaust tract(including but not limited to a correctly sized intercooler) when used with correct sized injectors, etc.(rest of drivetrain[mechanical/electronic] being up to snuff) will never need to see water injection, thereby allowing one to setup the water injection as a safety backup incase other means of intake temperature control fail, or are somehow compromised due to events that are remedied quickly.

~suds

edit: I have used a water injection system on my porsche944 powered jetta with decent results (i couldn't afford the properly designed intake/exhaust/engine-internals) but i paid for it in the long run with a dead engine when i let my friend drive it to cali without making sure he knew that the washer tank needed refilling more often.

ZeroBanger

Show me ANY intercooled car that has ambient intake temps. show me any intercooled car that doesn't heatsoak on a dyno. Show me any intercooler that PREVENTS carbon build up in the engine. Show me any intercooled car that can drop the intake temps from 160 F to ambient in a matter of seconds. (Im refering to times after the car park on a hot day and it heatsoaks, or you get caught in traffic on a hot day and the temps go crazy).


Now take your best intercooled car and tune it to its max. lets say you can run 16 psi safely, but any higher will cause the engine to detonate...Put water injection on that same car and you may be able to run 20 PSI safely.

Im not knocking intecoolers (pun intended) . They have a place, but in my opinion they are a back up to water injection. Water injection will never have the absolute reliability or simplicity, but intecoolers will never have the same potential for cooling/antidetonation abilities....

btw...sorry about your old car. I dont recommend TUNING for water injection. Alot of guys do it, but its not reliable.

sudseh

>Show me ANY intercooled car that has ambient intake temps

a seperate(separate?) water-air intercooler circuit would be able to bring intake air near if not to ambient.

>show me any intercooled car that doesn't heatsoak on a dyno.

a short term event in my opinion


>Show me any intercooled car that can drop the intake temps from 160 F to ambient in a matter of seconds. (Im refering to times after the car park on a hot day and it heatsoaks, or you get caught in traffic on a hot day and the temps go crazy).

that would be the perfect time to have water injection since it is another "short duration event"


>Now take your best intercooled car and tune it to its max. lets say you can run 16 psi safely, but any higher will cause the engine to detonate...Put water injection on that same car and you may be able to run 20 PSI safely.

If you are going to be hitting 20PSI constantly, I believe engine upgrades, strengthenings would be in order. If you are only going to see 20PSI for 5-10second bursts only when trying to outrun the local fuzz, by all means, use the water injection.

>Water injection will never have the absolute reliability or simplicity, but intecoolers will never have the same potential for cooling/antidetonation abilities....

Any more complexity whether adding air/water intercooler with it's own circuit or water injection will inherently be more complex, somewhat less durable. but if the water injection only sees duty for brief periods of time, the life of the upgrade can be greatly enhanced(forgot the word i wanted to use)

>I dont recommend TUNING for water injection. Alot of guys do it, but its not reliable.

I think that was my main point. just poorly stated.

~suds

ZeroBanger

Air to water intercoolers are not as good as regular intercoolers. At first they are very efficient, but in daily driving A2W intercoolers will cause your intake temps to be too hot.

here is a quote from a company that sells both Air to Air and Air to Water Ic's.


How can an air-to-air intercooler be more efficient than a water based intercooler?
There is an overwhelming quantity of ambient air available to cool an air-to-air core relative to the charge air thru the inside of the intercooler (The iced down water intercooler is the only exception to this argument.). At just 60 mph, with a 300 bhp engine at full tilt, the ambient air available to cool the intercooler is about ten times the amount of charge air needed to make the 300 hp. Whereas the water intercooler largely stores the heat in the water until off throttle allows a reverse exchange. Some heat is expelled from a front water cooler, but the temperature difference between the water and ambient air is not large enough to drive out much heat. Another way to view the situation is that ultimately the heat removed from the air charge must go into the atmosphere regardless of whether it's from an air intercooler or a water based intercooler. The problem with the water intercooler is that the heat has more barriers to cross to reach the atmosphere than the air intercooler. Like it or not, each barrier represents a resistance to the transfer of heat. The net result; more barriers, less heat transfer.




I take comfort knowing that if I get a bad tank of gas or over boost or whatever, my car is protected.

How many intercoolers would let you run 12 PSI on 89 Octain with a 3rd gen Rx-7?

Also, your talking about "upgrading the engine to handle 20 PSI" that has nothing to do with my point. Im simply saying what ever the boost your car is "tuned" for, you can run higher boost safely with water injection. of course you cant run higher boost than the engine internals themselves can handle. But thats not the point here.

sudseh

For the website's water-air intercooler, are they using an additional one or two radiator+fan for the water circuit, and are they running a pump to circulate the water? (that would make a big difference)

I take comfort knowing that if I get a bad tank of gas or over boost or whatever, my car is protected.
That's what I'm saying as well. >_>


How many intercoolers would let you run 12 PSI on 89 Octain with a 3rd gen Rx-7?

Also, your talking about "upgrading the engine to handle 20 PSI" that has nothing to do with my point. Im simply saying what ever the boost your car is "tuned" for, you can run higher boost safely with water injection. of course you cant run higher boost than the engine internals themselves can handle. But thats not the point here.

I agree upto a point. I disagree that you should rely on the water injection to allow the higher boost levels.

rs_1101

off topic:

ive heard water injection used to be used on old muscle n/a's as well, the theory is this:
water, when converted to steam, expands greatly, which has an effect of pressurizing existing a/f mixture in effect creating greater total compression yeild.

true or not?

LowFreq

To put what ZeroBanger said into practical terms, water injection is perfect for the way I normally drive my car.
I don't drag with it, but I do occasionally engage in some 'spirited' driving, but that only amounts to me being on high boost for a few seconds at a time. I've got a dual-stage boost controller and the vast majority of the time I drive in low boost(10lbs mast). I'll set the WI to come on at 10 lbs and whenever I go into high boost, the WI will be there for an added safety net. I've tuned for fuel, so the WI will be a backup.

LowFreq

For a dual-stage setup, are the nozzles plumbed in-line?

ZeroBanger

You can put 1 nozzel at the throttlebody entrance and one just after the intercooler if you like. I have one come on at 4 psi and the other at 12 psi.

Trav

Not sure I'd believe that. I'm no thermodynamics expert, but common sense tells me that water expands when it gets colder, not hotter... (think ice).

I'd think that steam is going to take up less space than droplets of water.

Novacaine

actually if I recall correctly water is the only thing that expands when it gets cold. water also expands when it turns into steam. if you think water becomes more dense when it turns into steam you need to rethink some stuff. steam is not more dense than water hence it takes up a greater volume for the same amount. Steam is compressible but it will not compress to a point where the density is less than water without turning back into water and at that point for most purposes it is incompressible.

not that I believe in water injection for a NA car, but I couldn't let you say water condenses when it turns to steam that is just plain wrong

ZeroBanger

its the change from water to steam during the evaporation process that soaks up the intake charge and helps prevent detonation. This is why the water is injected at high psi through very fine misting nozzles.

OverDriven

Pretty much everything you wrote is incorrect.

-Joe

Novacaine

hahaha ok, please correct me then cause I would like to know the correct thing then.