This has been done a few times, but after witnesssing the advantage of water on the intercooler during my remap I thought I would give it a go, and show you guy's how I got on.

I read several other posts where either a seperate tank or the exisiting tank was used and the headlamp washer pump/circuit was used. But thought I could come up with something a little more 'factory fit'.

My solution :

Pump / Washer Bottle

I was going to go the seperate bottle / pump route until I spotted that the standard washer bottle pump had a little surprise in store.

Now I'm not sure if all Impreza/WRX are like this, but on my MY00 UK there was what appeared to be a spare location on the front of the washer bottle for a 3rd pump just to the right of the standard pump. The MY00 is fitted with 1 pump in the base of the washer bottle for headlights and 1 pump in the front of the washer bottle just behind the battery, for winderscreen.

Further investigation found that it was identicle to the standard pump location, all be it missing a hole for the pump to be inserted. It's even moulded to hold/clip the pump securley into place.

A trip down to Halfords and a suitable pump was obtained for £14.99, this being similar to the standard pump i.e about a 20mm 90 degree inlet for the washer bottle and 3/16 outlet for the washer hose. Note : This is not the universal one that the halfords catalogue, incorrectly advises for a Subaru Impreza.

A hole was then drilled into the washer bottle using a 22mm wood boring drill bit. A spare piece of rubber hose was then pushed onto the pump (very tight) and then the pump wedged into the newly drilled hole. A small amount of sealant (the same stuff I used to seal my tail-lights) was used to ensure a leak free finish.

Job done and looks factory fit, see below



Washer Jets
Hozelock micro-irrigation jets seemed to be the order of the day. Unfortunatley I could not locate any in my local B&Q and Garden Centre. However, I did source some similar items from the 'Gardena' range. These are also micro-irrigation and are a 360 degree misting nozzle.
Bargain price of £3.89 for 5. Not £9+VAT each as per the STi items.

These were fitted by piercing the rubber gaiter on the intercooler seal with a 3mm drill bit. The nozzles where then carefully pushed through on the left and right hand ends of the intercooler. They where then held in place by connecting the 3/16 washer hose (£2.49 from Halfords for 2.5 meters). This had to be warmed in boiling water before attaching to the nozzles.

A few carefully placed cable ties ensured that the nozzles are held firm and pointing the general direction required, see below




Manual / Auto Operation
The pump was grounded with a short length of wire via the washer bottle mounting point. The power feed to the pump was run into the car for connection to the switches / relays.

For Manual operation it is just connected to a standard automotive relay (£4.49 from Halfords) and switch arrangement. The switch providing the +12V to enrgise the relay coil, with and 2nd 12V source driving the pump.
Flicking this switch drives the pump until you flick it off again.

For Auto operation, the connection is as per the Manual, but using a vacum pressure switch (Ebay £16.99) between the On/OFF switch and a 2nd automotive relay arrangement.
Flicking this switch causes the pump to run when the pre-determined pressure level is reached. The particular pressure switch used can be set to switch between 4 & 15 psi.

At present I have 2 temporary switches poking out of the dash adjacent to the steering column (see below), until I can source/justfy splashing out for pukka subaru items.



Total Cost :

Pump £14.99
Relay £4.49 (2 required)
Washer Hose £2.49
Nozzles £3.89
Wire £2.49
Washer T-Piece £1.49 (2 required)
Pressure Switch £16.99

Sundries : Crimps, Switch x 2

 

cheers mate, top job.

 

Scott,

Did you not consider the Autospeed water spray controller, only about £40 for the bare board and thermistors etc. Not much more than the pressure switch but gives far far better control.

Install looks good btw.

Tony.

 

Im going to ask a stupid question now but im a newbie so its allowed lol

Just got an 02 STi which has this intercooler water spray thingy. I can see that its suppose to cool air down quicker or better by wetting the intercooler (im guessing thats what it does). Question is when and why would i need to use this and is it actually noticeable whenever you should use it?

I haven't dared touch it yet

 

Scott,
Very nice mate.
I must get round to sorting water spray for mine. (I've had the STI nozzles fitted for 18 months and have managed to get hold of the Subaru switches just need to time to do it)

 

When having my MY00 RR tuned the BHP/Torque figure was 309BHP/296lbft.
A cup of water poured through the scoop then increased this to 321BHP/312lbft. Hence why I have now fitted the above.

Your 02 STi, if UK spec will only have a manual switch. The JDM spec STi comes with a Manual and Auto switch.

The manual switch only fires the spray when pressed/released, whereas the Auto switch fires at a pressure level set within the ECU (IIRC).
In your case I would expect the best time to use it is when at a standstill in heavy traffic i.e when the engine heat is causing the intercooler to soak up a fair amount of the surrounding heat.

If then nailing it away from the lights etc...., a slightly water soaked intercooler would be of benefit.

 

Scott: Thanks for replying. I understand what you mean now. Its probably more of a benefit when stuck in town traffic to help stop it bogging down/losing power through heat soak

I take it i just press it once and release for it to spray a set amount or have got to hold it down? Hmmm I'll just press the damn thing this morning lol

 

i made my own system up, got an STi bottle off ebay for around a tenner, mounted it in the boot.



i bought the OEM manual dash switch and STi nozzles to finish the job.
its also controlled via my ecu to activate for 5 seconds everytime i hit 20 psi boost.

 

Recently read a post about tilting the rear of the intercooler ie angled as opposed to flat. I sprint mine, angled intercooler plus constant spray via a switch. Good results.