Water Injection

[lee_kelsey]

Guys,

 

Have recently purchsed a j-spec TT and am interested in what water injection would offer my cars performance/general running. I have seen a lot of you have this mod already, so any advice/hints/tips/costs would be much appreciated.

[Mark Ayling]

You're better off sticking to fuel injection mate, the engine will run better

 

...sorry, couldn't resist - excuse the thread hijack!

[Guest Martin F]

Water injection is generally installed as a safeguard against detonation at high boost pressures in warm temperatures i.e. summers like we used to have.

 

It's not so much a performance enhancer but more an aid to enhanced performance. If you mix water with methanol it will raise your octane level (when injecting) which may possibly allow you to run a slightly higher boost than you can without it.

 

If you want more in depth info take a look at :-

 

http://www.aquamist.co.uk/

 

There is a lot of info on their site.

 

As a ball park price the 1s system, which most of us use, is about £320.

[lee_kelsey]

Cheers Martin, will check out the site and swat up on the info.

[Chris Wilson]

Caveat: I sell water injection (ERL Aquamist systems, the basic race pump kit is 280 quid no VAT). I wrote the following text some time ago, it may help, also see ERL site at http://www.aquamist.co.uk

 

Water injection serves 2 closely related functions on a turbo engined

car. Firstly it cools the charge air temperature by utilising the 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 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 cubic foot. 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 water to be generated anyway, which is why cars

not driven on regular long journeys will rust out a mild steel exhaust

system form the INSIDE out. If water is added in the correct volume, via

the supplied and 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 existent windscreen

washer bottle or in a separate dedicated container. In cold conditions

it is essential to ad 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 and sludge out of the pump or jet. This should be

checked regularly for contamination and blown out if residue is

apparent within.

[THOR Racing]

That was a very good post from Chris and I will add that if you wish to use the water injection to raise boost levels to increase power it is VITAL in my opinion to fit some form of fail detection circuitry.

 

I personally do not think it wise to RELY on Water Injection and just blindly carry on at high boost even when you've no idea it's functioning correctly. So you checked it when it was new and when you last topped up the water bottle, but that was two months ago... etc etc.....

This can lead to pump damage or worse still detonation in the engine.

 

You need to know for certain that....

 

1: There is water in the reservoir tank

2: The pump has power

3: When the pump is pumping (activated), this isn't just when the switch turns on (although this is a start) but ideally sensing that water is actually flowing and there are no blockages.

4: Ideally someway of reducing the boost pressure to the electronic boost controller (if fitted) should any of these systems detect a fail condition.

 

Number 4 will be your tricky bit as non of the boost controllers do this (not yet :-) my units will. One day when I do a boost controller I'll add such a detection feature

 

I would say 1,2 and 3 are essential.

4: you can do manually when you spot the warning signal turn on.

 

 

Pete

[Chris Wilson]

Thanks Pete, and I agree with you. A boost controller with a fail safe reduction to stock boost would be great, surprised it's never been done before. The water control stuff is all available from me, and is listed on the http://www.aquamist.co.uk pages. I can offer discount on the list prices there too. Maybe you do some control stuff for water level too? I know you have it on your own car.

[Guest Terry S]

I have found the ERL pumps a little unreliable though. Anybody else? & before you ask they were in a nice dry place.

[Chris Wilson]

I have sold about 60 of them, and had 6 fail, at some stage. 4 were early pumps that were mounted in places that got water sprayed. The otheres were later (modded seals on the pumps) that failed for no apparrent reason. They have always been changed without quibble, no matter how old the pumps were, however ERL are now date marking the units internally and offering a 12 month warranty. So yes, failures have occured, but I have yet to find a similar high pressure pump at a reasonable price. Bosch do one, but it's over a grand...

[Guest Terry S]

I have had 2 go ( both bought via ERL). The last one they wouldn't replace because it was 1 month out of warranty.

 

I am not slating ERL, the system works extremely well. It's just in my case there have been pump problems. I have the pump mounted where the battery should be so it's always been in a nice safe dry place. I have always primed the pump when initially installed & the reservoir has never run dry. Go figure?

[pat]

I've been using the ERL kit for longer than I care to remember, and I too have had pump failures. In both cases it was due to water ingress into the pump controller board (which sits behind the ally at the outlet side of the pump). This was due to heat cycling; the air in the pump would expand as it heated up, and when it cooled back down it would draw water back in through the cable gland. This issue has now been addressed so it should be fine (also mounting the pump in a drier place than the engine bay probably wouldn't hurt). Also, in both cases, Richard sent me a new controller board FoC and my "downtime" was all of about 2 days.

 

With regard to its use as a performance enhancement tool, initially it will actually rob power. That power is used to vapourise the water; however in doing so it keeps the charge temperature rise due to adiabatic compression lower, which in turn means that the engine will tolerate more advance before knocking, and hence the small amount of power lost due to the vapourisation is easily offset by the increased advance possible. A well setup system will make lots more torque than one without the water.

 

With regard to failsafes etc... the very first thing I fitted was a knock monitor, so that as I started to play around with things in the engine bay I would know if I was in trouble. It is absolutely frightening to see what this can reveal about fuel quality... within seconds of filling up with a dodgy batch of fuel the thing will light up like a christmas tree. It's then just a matter of dumping a bit of octane booster into the tank and off I go again. I can also tell when my jet is beginning to get blocked as the engine gets a little "sparkly"l.... as always the first step to solving a problem is actually knowing that there IS a problem to solve. I'de suggest that anyone doing modifications to alter the power output fit a knock monitor... it's inexpensive and it will save your engine (if you take note of what it's telling you). Another very useful device to have is a lambda meter. You will see, at an instant, if you are about to melt a piston if it's running too lean etc.

 

With a controller like the MF2, there is a Pump Fault LED (and I think an output too). With this, one could interrupt the feed to the boost control VSV, thereby effectively disabling higher boost than the actuator pressure (typically 0.6 bar). It's quite easy to splice in and if you do run out of water, you'll not be able to run high boost until the tank is filled up again (pull in at the next petrol station and hey presto). You won't win any races in this state, but more importantly, you won't blow the engine either.

 

Hope this helps,

 

Pat.

[Guest Martin F]

Originally posted by Terry Saunders

I have found the ERL pumps a little unreliable though. Anybody else? & before you ask they were in a nice dry place.

 

Yep i've had two failures, one may have been on the car when i bought it . Luckily JIC warranty paid the majority of the first replacement and then the second one was so soon that the supplier and ERL were happy to swap out.

 

Both suffered water ingress so now i have moved it from it's original location into the engine bay.

 

Fingers crossed.