Water injection for dummies

[CEF11E]

After careful consideration I have decided that intercooling my car is not possible without major modification that i do not want to undertake as it would be expensive and defeat the perpouse of a cheap performance gain.

So my only other alternative would be to build a water/methanol-ethanol injection system so i can increase boost levels slightly

Keep in mind I do not want to run huge boost or run a bigger turbo than standard. I just want to be able to run .9 bar.

The other need for the water injection system is that i will be altering my AFR's using a Jaycar digital fuel adjuster and this will more than likely increase ignition advance. So i need to cool my intake charge.

So I have decided to build a water injection system to lower cylender temps and to prevent detonation.

The way i would like to hook the system up would be to use a nozzle in the intake pipe before the throttle body, then water line to a normal fuel pump (will be needed to overcome manifold pressure), then to a resivoir.

I have decided to activate the system with a hobbs pressure switch at about 5psi. The switch will power on the pump inturn squirting the water-ethanol mixture into the intake manifold.

The questions I have are

1. What flow rate should the nozzle flow be rated at for a 2litre VG20det engine running standard turbo and .9 bar boost

2. What mixture would be optimum for deionised water and ethanol of methanol?

3. will the added water in the combustion chainber reduce the amount of combustion space effectivly reducing the capacity of the engine?

4. I have also thought of injecting water after the AFM and before the turbo to atomise it better. Will this damage the turbo? I dont really like the idea of water going through the turbo.

Any other valid information or experience would be greatly appreciated.

[midnight]

normal fuel pump will not be able to handle water, it can corrode and seize, you will also need a solenoid to ensure water flow is cut.

1 water to fuel ratios should be between 10-15% u can go up to around about 25% but tuning problems can arrise. To calculate the specific amount it depends on the size of your injectors and your duty cycle.

2 it depends on application, maybe 70/30 water to alc

3 the added cooling effect of water actually increases the amount or density of air that can occupy the combustion chamber, making it more efficient or some crap like that.

4 before the turbo will damage the compressor wheel.

[CEF11E]

Thanks for the response

that all sounds great

My duty cycle goes as high as 75% at full bost at redline so 75% of 270cc (the size of my injectors) = 202.5

so i would times that by 6 as there are 6 injectors 6 x 202.5 = 1215cc

Giving that it looks like a nozzle that flows 120 to 180cc would be the right size?

Also providing i am using deionized water i was told a standard fuel pump would be fine as it will be a 2:1 ratio of water-ethanol

does all this sound correct?

Also is ethanol acceptable as it is less corosive than methanol and easier to get.

[midnight]

im not to sure on the specifics of alcohols so I cant help too much with those ones.

ur calculation on flow seems right tho. just remember that if ur system starts injecting at 5psi make sure theres not too much water at that level, you dont want to hydrolock your motor.

maybe redo the calculation with your duty cycle at 5psi

just a question? where are you sourcing your nozzles from?

[CEF11E]

not sure where yet. agricultural suppliers supply nozzles that deliver water droplets measured in microns!

[midnight]

I'll help you out abit then.

aquamist make nozzles specifically for water injection

http://www.aquamist.co.uk/sl/plist/frm-4.html

if you scroll down to nickel plated water jet and click the red arrow beside itll bring up a page with flow rates.

also on their site is a link to MRT, their Australian distributor

CAPA also sell nozzles for water injection

http://www.capa.com.au/prices_capa_perform....htm#capa_water

which I am fairly certain are aquamist.