DIY water injection

Chryzla · Post by **Chryzla** » Sat May 28, 2005 10:31 am

water/steam in the cylinder causes spark issues.

Abalistic · Post by **Abalistic** » Sat May 28, 2005 10:36 am

Before I had Starions, I had a Mazda 626 Rwd 2.0L Garrett T04 installed and setup By Mike Vine Turbos in Brisbane.
It used water injection by use of a good quality windscreen washer pump and tank. The water/methanol mix was 50:50, the main use of the methanol is to help the water spray to varpourize before it gets to the cylinders.
A pressure switch was used to sense the boost pressure, and once the boost rose to 6 Psi it would switch in the water/methanol pump. The car would then happly go up to 18 Psi with no detonation. At 20 Psi water/methanol would not stop it from detonating.
It's surprising how little you need for it to become very effective ( about as much as what comes out of a water pistol ), too much... and it stops the combustion, ( and you head butt the windscreen! ).
The car was dynoed at 155 Kw at the wheels at a modest 13 Psi.
Hope this info is of help.
A.

Junkers · Post by **Junkers** » Sat May 28, 2005 11:03 am

modest... :o

AB · Post by AB » Sat May 28, 2005 11:06 am

You don't need to inject ice/methanol to acheive less then ambient temperatures, water injeciton on its own is capable of acheiving 0°C and lower temperatures under the right conditions.

It is important that the majority of the water you inject has completly vapourized by the time it enters the cylinders, this is because water absorbs much much more heat by being turned from a liquid at 100°C to a gas at 100°C (aprox 85% of the heat) then it does from being heated from say 20°C to 100°C (aprox 15% of the heat). This is because of the special properties of water and other physics stuff which I wont bother going into unless someone is interested.

I would definatly place the water injection nozzle after the compressor/intercooler. I have seen pictures of a turbo that ran a water injection system before the compressor and the blade edges were all serated, which means tiny chunks of metal must of broken off and been sucked into the cylinders.

Also, when choosing a nozzle you want as fine a spray as possible. A good test for nozzles is to rig it up and spray the water into the air. It should linger round in the air like a mist and not fall to the ground, if it sprays up and falls straight back down the nozzle is no good.

Junkers · Post by **Junkers** » Sat May 28, 2005 11:20 am

Thanks for the tip AB, do I have to worry about the volume of water that goes in or will the nozzle be restrictive enough?

I really like the idea of this system that uses boost to force water out of the nozzle as it gets rid of the electronic aspect of most systems, K.I.S.S.

My main concern is that under boost it will force to much water out in which case you'd need to use the restrictor as shown in the picture, but as our cars run vac when off boost it could cause a few problems don't ya think? or would the restritor be so small it wouldnt be worth worrying about?

AB · Post by AB » Sat May 28, 2005 11:26 am

The nozzle should be restrictive enough if it is putting out a very fine spray but I wouldn't count on it.
What you could do to start with is rig it all up but have the nozzle coming into the cabin inside a measuring jug. That way when your boosting you can see how much comes out and how the spray pattern looks at different boost levels.

One more thing you have to be very careful of if you don't have a solenoid in the water line is a siphon effect. Once the water has gone up the line it will keep coming out once the car is off unless the water reservior is mounted lower down then the nozzle (I think?) I think there is a special valve you can put in to stop this, I will have a look around.

Junkers · Post by **Junkers** » Sat May 28, 2005 11:34 am

Maybe putting the nozzle on the underside of the intake crosspipe would be the best idea? Not sure if it would help entirely though? And would the spark issue be relevant with a mist like spray?

Chryzla · Post by **Chryzla** » Sat May 28, 2005 11:56 am

has to be just enough that it doesnt bother the spark, just enough that it doesnt stay liquid as it enters the intake manifold.

TD05 · Post by **TD05** » Sat May 28, 2005 12:36 pm

water injection is handy if you don't have a decent intercooler, I can run high boost for as long as there's water/alcohol in the reservoir, without losing power due to overheating of the intake charge.. Mine was done by Mike Vine Turbochargers in Brisbane it was already installed when I bought the car....

Junkers · Post by **Junkers** » Sat May 28, 2005 12:40 pm

Yea I run 13psi on a stock intercooler and it runs fine, I plan to not run any higher than 13psi as I want a fairly reliable engine BUT I want to raise my compression to 8.5:1, I am getting a bigger FMIC (much bigger, with alot more airflow) but I am in question whether it will do the job? or whether Water Injection will be worth the trouble.

Chryzla · Post by **Chryzla** » Sat May 28, 2005 4:38 pm

depending on how many 90 degree bends there are in your cooler piping depends how much boost you are actually getting into the intake.

13 PSI will be like 9-10 at the manifold. Depending on quality of intercooler, piping, no tiny leaks, how free flowing it is.. etc etc.

Junkers · Post by **Junkers** » Sat May 28, 2005 4:43 pm

Theres something like a 0.2 drop in psi, what do the bends do?

Chryzla · Post by **Chryzla** » Sat May 28, 2005 4:53 pm

basic physics, PSI is airpressure, everytime air hits a 'wall' it decreases in speed, hence slows down the pressure, hence less forced air.

Also where did you get the airflow tested? in a workshop?

Junkers · Post by **Junkers** » Sat May 28, 2005 5:18 pm

Have not bought cooler yet as I'm still learning, just was stated on advertisement.

Chryzla · Post by **Chryzla** » Sat May 28, 2005 5:55 pm

ah ok.

Many people dont agree with my statements on this, thing is do your physics home work, and you will understand where I am coming from.

Austarion

DIY water injection

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