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The mkiv Supra Owners Club

water injection


Guest lloydmcc
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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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Guest ldor1

[COOL][/COOL]

Chris, youre the man,

Had one on my Impreza and it kept the Knocklink quiet no XMAS trees lights.

Dont let the pump run dry. I fitted a float switch in the tank to prevent that happening.

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  • 1 year later...

Guys,

 

I've read alot of positive reviews on water/alcohol/meth injection.

 

A mate of mine was telling me that if too much is sprayed, it could actually blow your engine. I am not mechanically inclined, so please escuse the fact that I am unable to explain why. Is this true?

 

He was also telling me, there are 2 types of kits, the fixed and progressive rate ones and was explaining that the progressive ones are better.

 

Can anyone shed some light on this?

 

Thanks

 

Dudley

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Guest DaveWilko

I have a Coolingmist water/meth system in my Mk4 Golf Gti 1.8T. You can check intake temps with VAGcom. When the water inj kicked in the temp dropped instantly from 28degrees to 14. Its like a fmic in a bottle but with the added benefit of increasing your fuel octane. On the REVO adjuster I had the timing set at 9 (as high as it will go) which is supposed to be used only with race fuel and the ECU only backed off the timing slightly when the boost spiked at 3500rpm.

 

Coolingmist is great value. I got the kit with the in-car variocontroller which makes setting it up a lot easier. You control what psi it kicks in at and what psi it reaches maximum flow at and also the flow rate of the pump. I think it cost me about £250. The cheapest aquamist system is mid £400s

 

You can't do damage with too high a flow rate but you will lose power and might even feel the engine misfire. To set the system up properly on a supra you would really be better using a dyno. It was easy on the golf with vagcom giving realtime data

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Guest DaveWilko

Hehe whistleblower! Stealin the man's thunder :D

Sure at least he made the effort to cut and paste it.

Wherever it came from its all good. I'm a big fan of water/meth. I've lost my hair but u should see the size of my....

 

Club member :p

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Guest DaveWilko
Using a 50 / 50 percent by volume water / methanol

mix will actually help increase the octane of the intake charge, as an

added benefit.

 

When using methanol as a fuel in spark ignition engines it can offer an increased thermal efficiency and increased power output compared with gasoline due to its high octane rating and high heat of vaporisation. It's low energy content of 19.7 MJ/kg and stoichiometric air fuel ratio of 6.42:1 do however mean that fuel consumption (on volume or mass basis) will be high.

 

Why else do dragsters use methanol?

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Guest DaveWilko

I don't know about better. Most of the systems on the market use a sureflow pump. The coolingmist controller gives great control. You can even plug a laptop into it and alter the way the mix is delivered using their free software. It was mainly the price that affected my decision but it helped that a friend of mine was using coolingmist with good results too. Have a look at their site . I would recommend adding the filter and block detector to the kit.

 

http://www.coolingmist.com/

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All positive comments on water injection so far :eyebrows:

 

Can't wait now as im having the latest Aquamist kit in pic below fitted to my car this Wednesday ;)

 

It's the new HFS-5 Water Injection System by Aquamist.

 

Will be fitted by Mark@Phoenix wiring by Matt Harwood & mapped by Ian C :eyebrows:

 

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I don't think any of us really doubt its effectiveness.

 

My question was really that if sprayed in excess, could it cause damage to your engine?

 

I was actually thinking of buying one of the non progressive coolingmist kits:(http://www.coolingmist.com/pagedisplay.aspx?feature_key=standard).

 

It apparently comes with a boost sensitive switch and you have to let them know how much horsepower you currently have so they can provide the correct jet size

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Guest DaveWilko

wooo! looks tasty! Do you have a methanol supplier? I get mine from a lab supplier. Its as pure as you can get. Costs me £18 for 5ltrs though. It is a lot cheaper from a regular chemical supplier but the ones in my area only sell 50gallon drums!

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Guest DaveWilko
I don't think any of us really doubt its effectiveness.

 

My question was really that if sprayed in excess, could it cause damage to your engine?

 

I was actually thinking of buying one of the non progressive coolingmist kits:(http://www.coolingmist.com/pagedisplay.aspx?feature_key=standard).

 

It apparently comes with a boost sensitive switch and you have to let them know how much horsepower you currently have so they can provide the correct jet size

 

 

No it definitely wont damage your engine. The most it will do is drown the combustion process making the engine misfire and stall. The basic kit is a lot cheaper but it delivers the mix at one speed. The vari-control is well worth having as it starts pumping at a low rate and rises as the boost rises. You will eventually save the extra cost of buying it as it uses less meth than the basic kit.

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No it definitely wont damage your engine. The most it will do is drown the combustion process making the engine misfire and stall. The basic kit is a lot cheaper but it delivers the mix at one speed. The vari-control is well worth having as it starts pumping at a low rate and rises as the boost rises. You will eventually save the extra cost of buying it as it uses less meth than the basic kit.

 

 

Just the response I was looking for Dave. Now I can justify shelling out for the vari-cool kit.

 

Thanks!

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Boost triggered WI is OK for a charge cooling or det suppression, don't know why they would calculate jet size by BHP?

using to big a jet in the scenario would lose you some power, and can cause bog down,

to get the best out of WI the Aquamist 2C and the new HFS-5 that lui is using is a much better bet, as this uses the HSV which to all intense is a fuel injector for water and so can be controlled and mapped by a suitable ECU, far better than the pressure triggered systems, as you then have precise control throughout the RPM and load range, and with the added benefits of the DDS3 and V8 etc you then have the added fail safes of map switching and boost cut should you run out of water or other related problem.

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The new HFS-5 that lui is using is a much better bet, as this uses the HSV which to all intense is a fuel injector for water and so can be controlled and mapped by a suitable ECU, far better than the pressure triggered systems, as you then have precise control throughout the RPM and load range, and with the added benefits of the DDS3 and V8 etc you then have the added fail safes of map switching and boost cut should you run out of water or other related problem.

 

Cheers Dick mate could'nt of described my system that i have in short terms any better :cool:

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Guest DaveWilko

I have no doubt you are correct but what price is it? With the current exchange rate the yankee kit is great value for those of us on a budget.

 

Also as a very rough way of setting it up, if the engine bogs down, even with the most basic system you adjust the pump pressure so it doesn't bog down :p

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