Do you retail the aquamist setup? I just want to get a idea against costs here...

 

PS I am resigning myself to the fact that I need this to be a tested scientific mod. Hence aquamist looks like the likely way to go. Damn it. I want to build one but as Danno points out, better that its smart, and tunable with the Link. So which Aquamist model???

 

I am developing a setup, something like the aquamist but half the price.

 

With data recording, block failsafes reducing MAP, and variable flow on load? I would be keen!

 

Remember that the water-controller on the Link-2 isn't water-injection, it's water-spray for external misting on the intercooler. It sprays on for a time interval, then off, then on again...

 

Yes, I know, I am running it from time to time! On a VDO pump... what Aquamist setup would you reccomend Danno? Ie model number... tested any?

 

The fancy $2000 aquamist setup is not really needed. You have to remember that almost everything on that aquamist site assumes no intercooler. Then it would be relatively important to increase rate of water as the mass air flow increases. On our cars you just set the cut in point where you think (at what boost) the threat of detonation starts. There is only a moderate difference in mass air flow between that point and max power. Since the engine is not quite as sensitive with rate of water flow as fuel flow, this will be more than adequate.
Also, as the RPM rises, for any given amount of boost the potential for detonation decreases (providing the timing isn't way out of wack), so the slightly less % of water is welcome.
I've said this before: when dealing with water injection; more is definitely not better. You need surprisingly little, especially because we have an intercooler.

Aquamist has good parts with good fittings.

 

Ok, so how do you determine the proportion of flow? Thats the issue for me. People use variable PSI rated pumps, 60-140psi more commonly, this is an issue for determining the amount of water to inject...

PS I can get an aquamist setup here for about USD450

 

NZ951, the Aquamist 2 will interface with your Link-2 and the System2d is a good value in a standalone system as well.

The trick with water-injection is that it's a substitute for extra fuel to combat detonation. So rather than just an air-fuel ratio curve on the dyno to look at, now you have a 3-way system of air-fuel-water ratios. Above a certain amount of boost, around 18-20psi and turbo-outlet temperatures of 175C+, more fuel won't help. You can add fuel beyond 10:1 where you're washing off the oil from your cylinders and it would still be knocking & detonating. Retarding spark beyond a certain point raises EGT to dangerous levels as well.

What helps in this nether-realm of high-boost is water-injection, but it needs to have 3D mapping like fuel as well. As boost increase beyond 20psi, fuel doesn't increase linearly, but water is added. So at 22psi, you may actually have a 13:1 air-fuel ratio with a certain amount of water. By 25psi, fuel may not increase that much, but you'll have double the amount of water added. This relationship also increases with RPM as well. Part of this is due to the volume of air that's displaced by the water, and part of it is due to the cooling effect.

 

mmmk so the 2d system is the one you would reccomend, what is the interaction it has with the Link?

 

"This relationship also increases with RPM as well"

I'm sorry Danno, I have to disagree with you there.
Rate of water should increase if there is a big difference in boost spread between starting to inject water and max boost. But injection rate should not increase with increasing RPM; believe it or not. I know there is literature that says otherwise, but this is not good for max power, unless your willing to progessively advance timing as well. Of course, if you have 50% more heat at high RPMs vs mid RPMs, that might be a different story; but then that would be an indication of a bad turbocharging system.

 

Home made plans: both have parts lists and sources

http://www.turbomirage.com/water.html

http://members.aol.com/taylorafdmb/water.html

If you use a couple of check valves in the water line from the tank, pump can be installed above the water source.

 

"mmmk so the 2d system is the one you would reccomend, what is the interaction it has with the Link?"

The System-2D is a complete standalone water-injection system with 3D mapping. It doesn't need any interaction with the Link at all. I guess you can replace some of its inputs like its MAP-sensor with a trigger from the Link to activate it. But it will still use its own 3D map to inject water based upon RPM X boost-pressure.

"Rate of water should increase if there is a big difference in boost spread between starting to inject water and max boost."

Boost can be constant at 4000rpm, but at 6000rpm, that same boost will flow 50% more air-volume. Assuming X moles of water injected at 4000rpm cools Y moles of water by 50-degrees, then that same X moles of water injected at 6000rpm to cool 1.5*X moles of water, will give less than that initial 50-degrees of cooling. Remember that water-voume has to increase to match the larger air-volume that's flowing at higher-RPms.

That's beyond just the increase necessary to overcome the difference in boost-pressure if you higher-boost-pressure. For example, if you have a pressure-switch that's activated at say... 10psi, but your max-boost is 15psi?? How do you account for the difference in air-flow & air-temp increases as boost builds from 10psi to 15psi? Assuming that you want the same temperature-drop of... 50-degrees at max-boost as at the initial 10psi start point, how do you do that?

"I know there is literature that says otherwise, but this is not good for max power, unless your willing to progessively advance timing as well."

These are two completely different factors. You always have to progressively advance timing with RPM. That's because fuel will take Y milliseconds to burn regardless of the RPM. At 6000rpm, you need about 30-50% more ignition advance than at 3000rpm to get to get optimum performance. How that relates to water-injection is totally separate.

"Of course, if you have 50% more heat at high RPMs vs mid RPMs, that might be a different story; but then that would be an indication of a bad turbocharging system."

Depends upon what kind of turbo and flow-rates you picked. "Bad" is too simplistic a judgement. It's the usual lag vs. power issue. Sure, you can pick a turbo that's most efficient at 6000rpms, but you'll have a lot of lag down low. Since most people are going to be using water-injection with the stock K26/6 or K26/8, the reverse is true, it's most efficient in the mid-range. These are the actual data I've measured on a K26/6:There is never, ever anything that's black & white, all-or-nothing or yes/no that you can clearly say about engine-management and extracting maximum performance. It all depends upon numerous factors and depending upon the actual values of those factors, you'll have certain results. For some people with certain applications, results ABC will be fine. For others with different goals, results XYZ will be more like what they're looking for.

So in a water-injection system, a budget is definitely one of those factors. But... for the $500-600 that the Aquamist System2D costs, I would think that's a bargain for the versatility. Think of your time in research and in re-inventing the wheel, and calculate that in dollars at your current wages. Then compare that with how much time it takes to order the Aquamist. Many of you who are looking for results ABC may end up with XYZ instead. Then with the additional overhead, time, R&D in upgrading your initial water-injection system, you'll be in the red for sure (compared with buying an Aquamist the 1st time).

FWIW, the System2D can do fixed-volume injection straight across-the-board, regardless of RPM, or it can do rising-volume with RPM. And extrude that across a 3D map with boost as well. So that's a system that can be as simple as a pressure-switch, or as intricate as an entire EFI system; just for injecting water. I would have to say that the versatility available with this would allow you to extract more performance and safety out of your car than any simple pressure-switch activated system.

BTW, we haven't even touched on water pressure yet. Anyone want to discuss why 100psi is better than say... 60psi or 75psi???

Then there's the issue of what kind of water to inject: plain tap-water, bottled drinking/mineral water, light/diet water or heavy-water, distilled water, ambient-temp water or chilled water, water with and without emulsifiers, water & alcohol blend, what kinds of alcohols in what concentrations, and for the weight-conscious racer, dehydrated water.

 

Hi Danno; you put alot of effort in your posts and everybody here appreciates it.

Just a few things in responce:

Judging by your turbo discharge temps (which correlate to desiphering the compressor map), I would consider that a bad turbocharging system. I would not want to put my engine or my turbo through that kind of torture (that's why you want to use water injection, I guess; which doesn't solve the turbo stress by the way). If I want a powerfull turboed car, I have to tolerate some lag. If I can't, I should buy a mustang or a vette. But that's just me and your right, everybody has their own idea of what they want.

You will not have 50% more air at 6000 RPM vs 4000 RPM because VE drops off, especially with your high heat scenario.

The IC takes a good chunk of turbo discharge heat away before the water gets at it. Too much water only leads to high condensation temps with no increase in charge density. Therefore, it's also not necessary to match gram for gram the water in relation to air flow.

As the engine speeds up there is less time available to complete the burn from the sparkplug. But higher velocities speeds up the burn rate, so the ignition settings even out somewhat. I know that most engine management systems tend to generally keep a steady ignition advance from peak torque to peak power. There are obviously variations to this; every engine is different; some chips even drop advance a bit. Maybe, YOU increase advance with rising RPM, I don't know. I'm just saying with water injection, power can drop off at the higher RPMs without enough advance or reducing the rate of water. High humidity levels reduce the flame speed, so it's definitely a related factor.