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Steve, I've been a supporter of WI for years, however its not that "cool" a subject so hasn't really had anything like the same scale of investigation or research on the automotive side. Much of what is known came from Aviation activities around WW2! Its also a case of targetted problems, like focus on det. I also tracked through in the late 70's 80's what people where doing in the USA, but much of it was not very empirical, more sales hype orientated and aimed at fuel economy.
I've also followed the WI Forum for some considerable time, some of the stateside guys have been doing "field" research on their cars and the effects of WI pre-turbo seem to initially suggest that it seems to shift the "turbo map" on the graph so to speak - in effect at boost that would take you off the efficiency island, with pre-turbo WI you can pull it back toward "centre" but at the higher boost levels. I wouldn't claim to understand all the discussion in detail, but it looks promising!
 

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Yes, looks incredibly promising providing you can get the setup correct and reliable.

I dont like/agree with the use of race fuel as I use my car mainly on the road, but luckily water doesnt cost a whole lot, and i dont mind if involves carrying a huge WI tank in the boot...

Theres even talk on there that with that setup the use of an intercooler is more of a hinderance than a help, now that would be interesting...
 

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compressor wheel wear - my friend who did this on his Calibra didn't, as far as I remember, ever have a problem with this. However, he (a) always used distilled water and (b) may not have had it in this configuration for very long. I will check with him and report back (1) how long he had it like this for and (2) whether he inspected his compressor wheel for signs of damage, and what he found.

methanol - great stuff, does a nice job. Beware that some windscreen wash is ethanol based rather than methanol based and (this certainly used to be the case) this can damage the seals used in some WI pumps and can cause pump failure. A (different) friend went though 2 WI pumps before he found out what was going on. At that point he then discovered just how many windscreen wash products there were that used ethanol instead of methanol.
 

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I fitted WI with about 75,000 on the clock and it was still running ok when I sold it at 112,000. The compressor wheel was fine but as I said I always used de-ionised water.
 

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My friend has come back to me with this:
Around a year on the Calibra, I had also used it on my kawa turbo as the
main means of intercooling, not at such a high pressure though, so
atomisation was shit --- effectiveness was out of this world!

On the Calibra I used it to change the adiabatic characteristics of the
compression, it behaved like a bigger compressor. It would even create
compressor surge if I overdid it.
And with respect to compressor wheel damage, he said that there was none at all.

Do we know that the people who suffered compressor wheel damage only used distilled water and ran with a proper air filter? The damage may not have been down to injecting water pre-compressor.
 

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kingsley,

I haven't grasped why you would want to inject pre compressor.

Traditionally you use the intercooler to remove as much heat from the air as possible, post intercooler inject the water / methanol and use the latent heat of evaporation to pull the temps down further.

Injecting at any time pre intercooler means that you are reducing the temperature differential at the intercooler which is kinda self defeating.
 

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NISFAN said:
Some people use a very simple DIY WI system that relies on boost pressure being fed into a sealed water tank to control the water flow through a small orifice. This obviously would only work spraying into the low pressure side, as the pressures would even out if you injected it after the compressor.

Very simple and cheap system, but a bit dodgy for my liking.
What about a pressure switch of a washing machine set to say 1.0 bar that activates a headlamp wash pump that sprays into both the turbo inlet and onto the intercooler. You could have a methanol mix which would cool the charge even more.
 

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Hugh Keir said:
kingsley,

I haven't grasped why you would want to inject pre compressor.

Traditionally you use the intercooler to remove as much heat from the air as possible, post intercooler inject the water / methanol and use the latent heat of evaporation to pull the temps down further.

Injecting at any time pre intercooler means that you are reducing the temperature differential at the intercooler which is kinda self defeating.
Hugh- Read this, it explains http://www.aquamist.co.uk/phpBB2/viewtopic.php?t=267
 

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Steve,

I haven't been able to read all the aquamist thread yet. Has anyone carried out some back to back testing to prove the no water injection, WI after the intercooler, WI before the compressor theory using the latest spec aquamist jets.

The gist of the claim seems to be that the full benefits of the latent heat of vaporisation are not available unless you remove the heat from the air by first removing it from the compressor wheel.

Not sure if better atomisation of the injected fluid occurs as well.

bill Shurvinton writes

Firstly you have to get rid of the heat, and secondly you need to take power out the turbine shaft to perform the heating.( heat is work and work is heat).

Now with the right level of water injection, the heat is removed before it builds up, pushing the compression closer to isothermal (not all the way, but closer). In round terms this is about 30% more efficient (less exhaust gas required for the same boost, or more boost at the same exhaust flow).

Exhaust gas heat is wasted energy, so it’s loss is no loss of work done, however the compressor might be more efficient at pumping air if it was denser, so there might be an advantage there.

Can you sum it up for us before I get my ear bent for not concentrating on what I am paid to do?
 

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RB211 - without chapter and verse, water particles like to club together to form bigger droplets, which in pre-tubbie terms you wish to avoid as that is potentially :rolleyes: detrimental to the blade. One way of avoiding this is to run very high pressure through very small nozzles to give the desired levels of atomisation. The pressure we are talking about (100psi would be nice) is not headlamp washer territory! It's a bit like saying why don't I use the dash fan as a turbo.

Hugh - the WI forum has been steadily getting more interesting with more participants, didn't help when it went off line a while back and postings seemed to get lost. Its just begining to scratch the surface on the subject and many aspects are still "finding their way". Explanations of exactly the how and why are still evolving, some of it is "this action begets this effect, don't know exactly why yet, but an answer will come eventually". Key issues seem to be getting a small enough nozzle, getting the nozzle in the right place, pointing toward the right location and fed at a high enough pressure whilst avoiding larger droplets forming and/or fluid on the walls. The right place seems to be resolving itself (within inches of the blade and central ish in the tract), pointing (at the spindle seems good) and pressure (in the order of 100psi). Comments seem to suggest small enough nozzles do not seem to be readily available. Further experiences may well refine matters further, like does it really need to be as high as 100psi and 10micron nozzle minimum. Its also true that a dose of methanol/water mix brings benefits. Fact is, quotes of 30%+ efficiency improvements makes everyone light up akin to declarations of finding the Holy Grail!

I'm sure many more revelations are to come.

DaveG
 

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What a really interesting thread, still say its more popular statistically in the poultry trade though. :D
Not keen on the sand blast damage to the impeller wheel !!
High pressure for atomisation certainly but I cant see an answer to the formation of droplets caused by water vapour condensing or should I say adhering to with laminar flow , before being attacked by science students :p the side walls of the tract apart from having the nozzle directly in-front of the centre of the impeller. Which would of course provide a restriction to the air flow in itself. Would you not reap a smaller but significant temperature drop by injecting just after the turbine ? saving the mechanical damage on the compressor wheels ? And what about a purge valve for the inter-cooler to dump any excess water and prevent build up activated on throttle lift ,like the dump valves?
Realistically though - How large a water tank would be required to last the equivalent of the petrol tank :rolleyes: No Smart 20 minutes at Knockhill comments please, :D at say 50% Wot use ?
Cokey
 

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From what I've read on the matter you need to run about 10-15% water for it to be effective. But the WI is only active when on boost. 50% water, 50% methanol alos seems to be the way to go, plus the methanol slightly increases the RON AFAIK. Aquamist kit can work just fine with this mix AFAIK. Even if it was on 100% of the time a 10litre tank would be more than sufficient for a tank full.

There are various checks on the Aquamist kit to alert you to failure. I would have thought this could be used to power a boost controller, so if the WI fails it reverts back to stock boost.

My last car was a supercharged BMW. Due to lack of space WI is quite popular. Some guys are running around 11psi plus with a centrifugal SC on SUL without an intercoler, just WI, on an engine with about a 10+:1 CR.

Aquamist do a system that monitors the injector pulse. The boost is also monitored. Using this the percetage can be accurately determined and doesn't require any mapping.

I think the best place for it is after the IC.
 

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It seems a tiny nozzle before the compressor for turbo efficiencey reasons, and a more normal size jet for the usual det supression near the throttle seems the way to go.

But to be honest as id only want to use WI in a det supressant way (ie the usual way) as a last resort (i prefer to rely on GOOD mapping so the car dont det :p ), so maybe just the tiny nozzle before the turbo is the way for me, IF it does what it suposedly does, and itd just need a basic setup of a high pressure pump activiated by a boost switch, no point in a mapple one for a use like that.
 

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If it makes it more efficient, then technically yes, modern turbos give a feckload more power for the equivalent size than old ones as they more efficient.

But dont forget its not all about compressor flow, gas has to get back out the engine as well as in, if it was jus compressor flow we'd all have teeny lil exhaust housings.

If the ex housing is restricting flow it wont get you anymore top end, but it may well get you some on the way to the top end even if no more up top due to restrictive ex housing.

All this is deffo worth a test...
 

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Just twigged that it should be easy to find out if pre compressor injection works, anyone with a power FC can read the airflow meter voltages, or better still a Datalogit or other logging software.

All that is required is one pass to maximum RPM with WI off taking note of the Air Flow Meter voltages at different RPM's, a second run with it switched on will either show an increased voltage representing higher airflow and corresponding power increase.

Job done, all the theorising can stop.

Still not read the Aquamist thread so the above may not be an original idea.
 
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