LukeSportsman

Like I said, it was likely just follk lore, like the 924 tranny being stronger. I thought better to pose the question now and get it answered then .......

I knew it "worked" , I just thought there were longterm issues. Glad to hear that its not a problem.

Do any of you guys mix alcohol in the spray anymore? Been a while since I looked into this topic...back in the 90's some guys I knew were trying it with some success.

TurboTommy

Guys,
the reason Corky Bell is not a fan of water injection, is because it only works if you really fine tune it and it needs to be reliable in order to protect your engine.

The amount of water is critical to get the best balance of power and anti-detonation.

Laust, I'm afraid your planning to inject WAY to much water. You have to remember that aquamist based almost all of their info for cars without intercoolers. Port water injection will not give good results unless you're able to inject only a tiny amount (maybe 15mL./min. per cylinder; depending on boost and ambient conditions). If water enters the cylinder in raw form (not evaporated), too much of the heat of combustion will be absorbed by the water. Yes, of course, you will have no detonation, but your BMEP will go down resulting in a net loss of power even if you have slightly higher boost.

Also, you want the water to displace the air because of evaporation. That will be the sign that maximum air density has been achieved for maximum power.

You are right that this should not occur before the IC, because then the IC is not doing all of its potential work.

With water injection, you will never achieve below ambient temps because the dew point of the entire system will be reached before that. Then again, you will have raw water entering the cylinders.

Burma Shave

I've read a little about a fuel cooler using a/c system. Ford is looking at it for next gen Lightning(500hp).Also in this months Forza magazine there is an Imola 360 that uses one claiming 19hp gain. I've searched the web but can't find any info. Would this acheive similar results to port water injection?

cantresjr

I've heard of people using windshield washer fluid with good results.

toddk911

"I've heard of people using windshield washer fluid with good results."

yep, they are running washer fluid for it's methanl content.

Your best bet is to run a dual stage system, one before the IC, which cools the charge but also helps to cool the IC much like an IC sprayer, then second stage right before the throttle body.

Bri Bro

Considering the amount of water in the tanks that have been talked about, what the point? This can only be used (tuned) for short durations. Are people tuning for 1/4 mile runs or for normal track use. I have also heard of water contamination problems in the TPS that caused all sorts of issues.

NZ951

Cry c2o... check them out. Very cheap

Laust Pedersen

“J Chen
How about spraying a fine mist of water at the inlet of the compressor as well? If we can control the heat build up within the compressor housing, would'nt it allow the compressor wheel to work more efficiently?”

That would be against my design principles of taking full advantage of the intercooler and minimizing the displacement of oxygen needed for power. LukeSportsman brings up an interesting point on cavitation, which may be possible in an oscillating low pressure environment. Take a look at airplanes at the start of the runway on a humid day, there is dense fog in the jet engine intake, because the very low pressure pulls out the water in the air. The high intensity noise creates oscillating micro-bubbles, which through cavitation erodes the turbine blades. I do have “insider information” that this is a problem for Boeing. Whether or not that is a problem for our turbochargers with water injection in front, I can only guess and my guess would be probably very little effect, since they are not very noisy.



“TurboTommy
The amount of water is critical to get the best balance of power and anti-detonation.
Laust, I'm afraid your planning to inject WAY to much water. You have to remember that aquamist based almost all of their info for cars without intercoolers. Port water injection will not give good results unless you're able to inject only a tiny amount (maybe 15mL./min. per cylinder; depending on boost and ambient conditions). If water enters the cylinder in raw form (not evaporated), too much of the heat of combustion will be absorbed by the water. Yes, of course, you will have no detonation, but your BMEP will go down resulting in a net loss of power even if you have slightly higher boost.”

OK TurboTommy, I’ll go out and tell my car to misbehave according to you beliefs. Joking aside, I have had the system in the car for about 3 months and it is working extremely well, with an on/off transition (@ 13 psi) that cannot be felt, except when the engine is cold.
The amount of water (water/fuel ratio) needed is far less critical than the air/fuel ratio, which typically is about ± 15% before the combustion becomes erratic. I am running a little less than 100ml/min/cyl, which actually tapers off at higher boost pressure (constant absolute water pressure). Ideally I would like to run water flow proportional to power generated (more water for increasing pressure and rpm), but it works pretty damn well even without this control, I am even (pleasantly) surprised. My experience is that the amount of water tolerated is very broad or said in another way the peak power is a very weak function of the water added. Remember also that the amount of water injected is only a few % of the water naturally generated in the combustion process. Again, the main benefit is eliminating detonation and reducing the thermal stress on the engine internals and the turbo turbine. Look at the many posts on the necessity of setting an upper limit on the exhaust gas temperature.
No, my BMEP will go up and would you consider 30psi a “slightly higher boost”?


”Also, you want the water to displace the air because of evaporation. That will be the sign that maximum air density has been achieved for maximum power.”

The displacement of air (oxygen) with steam is a “necessary evil” not a desire and port injection will minimize this effect.


”You are right that this should not occur before the IC, because then the IC is not doing all of its potential work.”

Thanks.


”With water injection, you will never achieve below ambient temps because the dew point of the entire system will be reached before that. Then again, you will have raw water entering the cylinders.”

You are right if ambient has 100% humidity, otherwise it certainly is possible. Have you ever experienced the nice and cool water misters in Palm Springs? And I am sure many other places. They actually cool the air and not just due to evaporation on the skin.


“beab951
Considering the amount of water in the tanks that have been talked about, what the point? This can only be used (tuned) for short durations. Are people tuning for 1/4 mile runs or for normal track use. I have also heard of water contamination problems in the TPS that caused all sorts of issues.”

Typically the amount of water used is about 10% to 25% of the fuel used, setting the water injection trigger point to for example 13psi, this must be multiplied by the time fraction spent above that level, which for aggressive driving is maybe another 20%. So in this case the water usage is 2% to 5% of the fuel used. The windshield washer tank appears to hold 1 gallon or 5% of the fuel tank resulting in a needed water refill for every 1 to 2.5 fuel tanks, which is in accordance with my observations.
If port injection is used the TPS will not see the water, good concern though.


BTW, alcohol certainly is a good thing in colder climates as an anti-freeze, but it does not compare to water with respect to latent heat. Using it as a high octane fuel would probably affect the air fuel ratio.

Laust

Duke

Laust, do you monitor your EGT?

J Chen

Hi Laust,
My suggestion of a fine mist at the
inlet of the turbo does not replace
the need of the intercooler.
The idea is to create a denser
enviroment within the compressor
housing with will allow the compressor
to work more effectively. I don't think
the amount I'm talking about will create
cavitational problems.

jimbo1111

The air actually gets heated up because of compression. Not heatsoak. The higher the pressure the higher the temp and vice verse. Trying to cool off a compressed charge in any way will reduce the pressure as well. Without a pressure drop there is no cooling effect. Most factory intercoolers are built with a restriction purposely to reduce pressure and temp at the outlet. After market intercoolers rely more on larger surface area than restriction to lower temps with the same results. Low temp/pressure charge. Almost like a refrigeration cycle.
To succeed in a proper water injection system you must start out with the turbo. You must find a turbo that is efficient at 40 lbs. boost then cool the charge down to 25 lbs using water injection/intercooling for the best effects.

toddk911

"but it does not compare to water with respect to latent heat"

Yep. Nothing... compares to the latent heat effect of water. I.e. nothing cools/extracts heat better than water.

In regards to lower than ambient, if you were running a cooled charged ( via adding alchahol/methanl so the injection could be cooled much lower than freezing) I don't see the probelm with geting intake temps below ambient, especially in summer.

TurboTommy

Laust,
so are you actually running 30 psi boost? Can your compressor flow that much? Can your exhaust side deal with the back pressure? Your IC will probably have a fair amount of pressure drop. With that kind of boost those issues would have to be addressed in order to get the real net power gain that 30psi can provide. Yes, then a little more water would be needed for maximum power gain. Otherwise it would be just a bandaid to prevent a bomb from going off.

"also, the amount of water injected is only a small % of the water naturally generated in the combustion process."

This is not correct. The water in the combustion process comes from the humidity in the air. If you do some research, you will discover that your engine will probably ingest about 100 to 150 mL./min. of water (depending on ambient conditions) Judging by where you live, maybe even less. You said you injecting 400mL. of water per minute. That's a huge percentage.

And, you absolutely want maximum evaporation. Don't you want maximum amount of air molecules to mix with your fuel? You need this evaporation before the intake valves for maximum density gain.

TurboTommy

Todd,
if you run only methanol injection, your absolutely correct, you could get slightly less than ambient temps because you're not adding any humidity to the system.

Laust Pedersen

J Chen
But still, by cooling in front of the intercooler will diminish the amount of calories it extracts, since that depends on its outside / inside temperature difference. It is probably true that in your proposed case the compressor does not have to spin as fast (for the same volume displaced) since the air is denser.
Another slight advantage by running port water injection is that all the induction components between the turbo and the intake valve are kept hot (obviously less so after the intercooler) thereby acting as minor additional intercoolers (including the intake manifold).


TurboTommy

Yes, I am actually running 30psi, although I am only up there for short periods, since it is relatively new, but so far no complaints from the engine and lots of “push”.

The exhaust side can handle much more backpressure than this creates. I discovered that inadvertently when searching for lost boost (10psi max).
When cleaning up the vacuum system and ensuring that all the hoses were well connected did not solve the problem, I blocked the wastegate valve with a piece of sheet metal and could now get 15psi of boost, but the turbocharger was getting a bit noisy at that level. It then turned out that the last of the two ceramic bricks in the catalytic converter had cracked and a piece was eventually blocking 90% of the flow. Grinding out half of the cat guts solved the problem and I was back to 30psi. I believe the noise from the turbocharger was due to extreme pressure on the exhaust side not being matched by the intake side, overloading the thrust bearing in one direction, or slightly scraping the turbine against the housing. Fortunately there appear to be no permanent damage form this incidence, which I estimate to have created about 60psi on the exhaust side. It even popped off the exhaust sampler connection.

Oh yes, it is correct that the amount of water injected is only a small percentage of the water emitted. The ideal combustion process is HxCx + O2 + N2 -> H2O + CO2 + N2, essentially the nitrogen just passes through. Even though the emission products CO, HC, and NOx are receiving much political attention, they pale in quantitative comparison to the main products of water (steam) and carbon dioxide. Here is a reference to a straight forward combustion chemistry discussion: http://www.autoshop101.com/forms/h55.pdf. The amount of products consumed and produced can be quantified by a chemist (not my strong point).
BTW, it is interesting to think of our engines as “half steam engines”. They produce a lot of steam and only consumes very little water (humidity and for some water injection).

Laust