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Good, does it job well.

IMO should ONLY be used as an extra failsafe mechanism to prevent a engine disaster if something seriously out of usual perameters happens to make the charge temp go up hugely.
Unlike what some people use it for, which is to prevent the car blowing up under normal hard driving conditions.
 

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Works great on chicken breasts :D
Im with steve here only for extreme applications ie drag racing.
Cokey
 

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I ran it on a Saab 99 Turbo for 3 years without any problems. However, the reason behind using it was that there was not enough room under the bonnet for a decent intercooler. I always used filtered soft water though as otherwise your inlet turbine looks like it 's been sand blasted and it gives up after a while.
 

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SteveN said:
You injected it BEFORE the turbo?
Yes, it was an official Saab kit so I just followed the instructions. Also bear in mind that this was 15 years ago so turbo charging was not as advanced as it is now. Certainly made a difference though as it made 165BHP at the wheels when the standard car was rated at 145BHP at the flywheel.
 

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R32 Combat said:
Water injection before the tubby must reduce lag too. Am I right?
Maybe but remember we are talking about a 4 cylinder, 1985cc engine with a Garret T3 and a compression ratio of 7.1:1 :eek: The word Lag was invented for this car :D .
It was great fun to drive but noooothing happend below 3,000 rpm and then bang you needed the next gear. 1280KG, 165BHP atw and more torque than you could shake a stick at (at 3k) it put a few cars to shame when you worked out how to keep it on the boil though :smokin:
 

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R32 Combat said:
Water injection before the tubby must reduce lag too. Am I right?
Umm... Water prior a compressor? How effective is your compressor - I mean, water resists compression pretty damned well...

Mario.
 

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A mist (which this is) is still mostly air and can therefore still be compressed.

Funnily enough I was speaking to a friend of mine only yesterday about various different water injection options. He used to have a Calibra Turbo and had done a lot of experiments with water injection. He said that a 0.4mm nozzle before the compressor was very effective, despite hium already having fitted a fairly large FMIC. He said that where the compressor outlet may be, say, 120C without water, it was maybe 60C with it. He also said he didn't notice any water pooling in the FMIC, which I was slightly surprised at.

I'm not sure of exactly how much power it was making at the end but it was somewhere between 300 and 350. Hardly impressive figures for a Skyline but pretty respectable for a Calibra.
 

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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.
 

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WI after the turbo is normal for controlling det, particularly at high boost/loads.

WI before the compressor has interesting effects on turbo efficiency and fuel economy........

Mario, you need to read more - you may learn something to your benefit. ;)
 

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I wrote the following for a Supra twin turbo board I an active on. caveat: I also sell Aquamist WI kits but genuinely beieve WI to be a must have on all turbo engines running more than stock boost.

Water injection serves 2 closely related functions on a turbo engined
car. Firstly it cools the charge air temperature by utilising an effect
known as the latent heat of evaporation. This property can be self
demonstrated very easily. If you pour something that evaporates quickly
like petrol on your hand it feels very cold. This is the rapidly
vaporising spirit removing heat from your skin and bloodstream by the
aforementioned process. By spraying a very finely atomised mist of water
into the inlet of a turbo engine when under boost conditions the
evaporation of the water into steam causes a temperature reduction in the air and
fuel intake charge. A cold charge is less likely to be subject to
detonation than a hot charge. A cool charge is also denser, able to
carry more air and fuel mix per unit of volume. These 2 properties of
water injection allow either less chance of detonation at a given boost,
maybe allowing lower octane fuel to be used, or to allow a rise in boost
pressure usage without detonation. These are very desirable goals for
any modifier of a turbo engine, or one using an engine mapped to run
on a higher octane fuel than generally available in the UK. Japanese
import turbo cars for example.

People ask whether squirting water into an engine causes corrosion. In
fact this is not a problem, the combustion temperatures under boost
ensure the water is turned instantly to steam and is ejected out of the
exhaust. The water mist is injected only when high boost is sensed via
a supplied pressure sensor switch. The basic combustion process of
hydrocarbon fuels causes LOTS of water to be generated anyway, which is why cars
not driven on regular long journeys will rust out a mild steel exhaust
system from the INSIDE out. If water is added in the correct volume, via
the supplied, calibrated jets, this is not a problem.

Even when used alongside a larger or more efficient intercooler, or
indeed when an intercooler is used in an application where one was not
present as standard, water injection can and does increase charge cooling
still further. Water can be stored either in the existing windscreen
washer bottle or in a separate, dedicated, container. In cold conditions
it is essential to add an anti freeze additive to the water to stop pump
damage through freezing. Windscreen washer additive serves this purpose
fine and the engine won't mind ingesting this solution at all. Or you
can add neat methanol, which is usually the anti freeze additive in
washer fluid anyway. Using a 50 / 50 percent by volume water / methanol
mix will actually help increase the octane of the intake charge, as an
added benefit. As a yet further advantage the latent heat of evaporation
of methanol is extremely high. A win / win situation. It is not however
obligatory to use methanol as an additive. All components of the water
injection kit that are in contact with the fluid are stainless steel or
able to tolerate water and methanol or screen washer additive without
degradation. A properly set up system does not use a vast amount of
water, in fact a modern car sized screen washer bottle used also for the
water injection reservoir will suffice admirably. A water filter is
included to keep any sludge out of the pump or jet. This should be
checked regularly for contamination and blown out if residue is
apparent within.
 

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The best place to inject water is onto the backs of the intake valves with individual injectors, like the WRC rally cars did. You need trick injectors though, and their Bosch water pumps were about 1k each...
 

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The water vapor occupies space in proportion to its partial pressure in the
mixture of gas.

If the partial (and saturated) pressure of the water vapor is less than the
pressure drop of the (water free) air going through the IC, then the
partial pressure of the air mixed with the water vapor will be HIGHER than
the pressure of the air after it went through an IC. Hence, more air to
burn.

Examples:

With an IC:
Pre IC manifold pressure= 37 psia (22 psig boost)
Post IC boost pressure = 35 psia

Manifold partial pressures, post turbo, no IC, but WI:
Air = 36 psia
Water vapor = 1 psia
Total manifold pressure = 37 psia

Note that the compressor is doing the same amount of work in either case,
hence should be about the same back pressure from the turbine on the motor.
Guess which one of these two cases has the motor ingesting more mass flow
of air ??
 
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