johnfelstead

I have spent the last three days designing and building a water injection system for my STi.

I decided to use the Aquamist system as a starting point and then build a system to my own requirements from that. I sourced the Aquamist from Lateral Performance.

I wanted to be able to control the water injection so it only came on above certain charge temps and boost levels, as triggering just off boost can lose you power at low charge temps (and uses more water than you need to). To do this I used a charge temp gauge with switched output supplied by mike rainbird to give me the temperature control. I then linked this into the boost controlled Water Injection output from my SECS display unit using a couple of relays to provide the temp/boost logic.

One of the big issues with WI installations is the pump noise/vibration being heard in the cabin, so to get round this I made a bracket to mount the pump, this is mounted onto the N/S chassis leg using two pre-tapped threads that have blanking plugs in them. The bracket is mounted on two industrial anti vibration mounts I modified, these are good for 18Kg each so are more than strong enough to hold the pump.

I then bought a pneumatic 90 degree taper thread fit 6mm snap fittings and installed this into the washer bottle underneath and am using this to feed the pump.

Next I mounted the water jet nozzle, the best place for this is on the exit of the IC at 90 degrees to airflow, and so I drilled and tapped a hole in the underside of the IC exit near the throttle butterfly.

Next I needed somewhere to mount the charge temp sensor, this uses a 1/8BSP taper thread fitting (same as a cossie plenum) so the only place that has a thick enough amount of alloy to do this was the BOV on the IC. So I drilled and tapped the BOV, then drilled through into the IC to get the thermocouple into the charge air.

Then it’s just a case of thoroughly flush out the IC to remove any swarf and install everything into the car.





































So I now have an efficient Water Injection system based on boost and charge temp, with a charge temp display on my dash.

Thanks to Mike Rainbird and Mark Aigin for the assistance, and a mention for Ahmed Bayjoo whose trigger thresholds for the water injection i knicked.

Creepy

Excellent piece of craftmanship John...
This weekend we're at the Ring till monday, maybee wee see you there ?

johnfelstead

Thanks. I am afraid not, a few other minor things going on getting myself ready for the Ten of the Best competition next weekend.

Enjoy the ring and keep it safe!

greasemonkey

Nice job John, looking forward to some with/without charge temp comparisons, and RR figures...

David_Wallis

hurry up with pat please..

What you doing this week?? you working??

How are you with geometry / suspension??

Can I have a hand prior to totb..either at stevens bbq. or whenever (assuming we aint pissed!)..

oh and can I have tutiton on driving again (serious!)

hope its going well
David

john banks

Looks great John. What temp/boost are you using for trigger?

Creepy

A little joke on this, but can't resist to post : In Belgium you could also use EL CHEAPO fuel from one of the "unkown brand" gas stations, it contains enough water to run on 1.5 bar in 35°C outside temp...

LOL

Creepy

Creepy

I was just wondering what kind of nozzle is inside the intercooler, is it just spraying water or does it make a fine mist ?, and what about the water reservior ? I assume that you have to use VERY CLEAN water to spray inside the engine so you cannot use normal wash fluid but distilled water with a small percentage methanol or so ???

Creepy

johnfelstead

The water pump only switches on when charge temp goes above 42 degrees C, it switches off when it drops down below 38 degrees C and it will only come on if the boost is above 7psi.

So in normal road driving, the WI never switches on, even when on full boost, it will only come on if i am nailing it or have been in standing trafic for some time. This means its going to use very little water compared to a boost only triggered system and will provide max power over the full charge air temp range, as injecting water at low temps loses you power.

I am using WI to help control charge air temperatures, not for active det prevention as part of a mapping strategy, it's there purely as a final Air Charge Temperature control safety buffer should the intercooler not cope with demand. This is how the GroupA and WRC engines are mapped to use WI.

I have been thinking about where i located the thermocouple and its not 100% ideal as its not measuring the effect of the water injection, to do this it should be located in the plenum, but thats a much more dificult instalation to acheive and would need the inlet plenum removing to enable drilling and tapping, so for now the current location will have to do. Mayeb after TOTB i will move it and then it will be spot on.

I am using tap water, i live in a very soft water area so mineral content isnt a problem. In winter i will look into using methanol as an antifreeze.

johnfelstead

the water nozle is an atomising jet and produces a very fine mist.

Tone Loc

iTrader: (1)

Very nice installation John. This is something i've been considering myself for the same reasons as you (i.e charge temp control). Be good to see how it fairs.

Tony.

rapac

jonfelstead OR anyone
I ll appreciate if you can shed some info how to set WI activated on boost in conjunction with inlet temperature.
My home made,Current set up

Water pump:110psi
Nozzle 0.4mm (with build in filter and check valve)
Activation:At 15psi(around 1 bar) by Hobb switch
Consumption:180ml /minute
ECU:M48pro(motec),fmi,etc etc
Thats on my97 with around 400hp at the fly and free of detonation (????).
I have run it for the last 2 years(as a safe guard) with the exception of winter days as inlet temps(after intercooler) do not raise above 6 to 7 degrees max when on full boost(1.5 bar) with ambient between 5-25 C.
Is there also a way of tuning car with WI taken in to account for more power without compromising safety at ALL?


Regards
From OZ

johnfelstead

i am not an engine mapper so wouldnt give advice on how to do that. Companies such as ERL do believe you can tune the engines to run more timing if you use water as an active tuning strategy. I suppose the best way to do this and stay safe is have a system that monitors the water spray flow rates and then switches the map in the ECU to a safer setting if the water stops flowing due to a blockage or being out of water.

It may be worth looking at the ERL website for more info.

rapac

Thanks for that.
ERL is marketed here(Australia) by MRT in Sydney.
On my next trip there I ll be visiting them .
Regards

dowser

Hi John,

Do you have any follow up information now it's been on and runnin g for a while. Did you take the opportunity to change anything while engine was out?

Thanks, Richard