I've been trying to work out a way to set up an I/c water spray for the up coming summer...

I had these considerations in mind:
Fully automated system
boost activated
variable run on time after switching event (boost)
Fine mist from the system/ limited water supply (approx 10 litre tank)

I've come up with the following:

Timer/ switching:
Jaycar Special function timer Kit# KC5379 cost $40



This kit features a variable duty cycle, 8 amp on-board relay and a variable switch on voltage user settable 0-5 volts <- the last part is the important bit!

Water delivery System:

The pump I'll be using is a medium pressure (30 psi) fuel supply pump......

Before anyone asks.........YES, DC motors work when submerged in water!

The actual pump I'm using is out of a Navara D40 diesel (in tank lift pump).

Cost $0 (pressure too low - replaced under warranty at work)



Nozzles:

Being a cheap skate...... I'll be using a pair of garden spec micro spray nozzles.

Cost $5!

Uber hi-tech metal ones

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Time to build the timer:

After about an hour I ended up with this on my table



Time to test it out..... Uh Oh! it's dead

After swearing at it for a while I found the problem.... I'd fitted a capacitor backwards.... DOH!

It lives !



Now.......How am I going to trigger it?

I could go a hobbs switch, but that would mean running wiring through the already cluttered engine bay, finding somewhere to tap a hobbs switch into etc etc.....Pass!

This timer has a user settable 0-5 volt trip point...where to get a boost related 0-5 volt input?
According to my workshop manual the factory MAP sensor has a linear 0-5 volt output....3.0 volts from the MAP sensor roughly equates to 12 psi.......Perfect!

The timer will be set up to trigger at or above 3 volts, it will pulse the water (fuel!) pump for 1 second every 2 seconds over a 10 second cycle. The timer cycle is also user adjustable....I'll just see how it goes.

I'm also looking into the possibility of incorporating a temperature switch to turn the whole system on or off depending on the temperature of the air passing through the i/c core.

The end result will be similar to this but the pump will pulse on & off to conserve water...



*Disclaimer* the footage is off youtube, it isn't mine. I'm sure someone else somewhere has done something similar to this and I don't profess to being a pioneer in the area of watersprays.

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I'll be interested to see how you go with this, Ross. I've seen a few DIY waterspray setups, but this one seems to be the most professional looking.

I'm guessing you'll be using the usual HOBS switch for boost pressures.

hey ross, there might be one issue with the fuel pump. It uses the fuel to lubricate the pump motor and bearings, so it will proberly seize in water after a few weeks

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Version 6 STI

The bearings are nylon, the water keeps the pump cool, the pump elements are nylon also and the only wearing parts will be the carbon brushes (we used to run in brushed r/c car motors in water to bed the brushes in).

I have some clear ethylene glycol I can add if corrosion becomes an issue with the pumps casing (it's plated anyway).

worst case, I can also get hold of an all plastic 12 volt submersible pump for $30 if need be.

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I have never heard of a motor using nylon bearings, usually they are brass bushes. but who knows, could well be.

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Version 6 STI

After going to all the effort for a smart controller, and full points for that, it would be a shame not to finish off with an effective water misting nozzle! The nozzle you have shown is a spray, not a mist. This will consume a lot of water and will not be as effective as the STi OEM "mist type.

Remembering a water mist evaporating off your intercooler is about 95% more efficient for heat transfer than just water running over the same area.

Seeing your keen to add some technology to the process why not add in a thermometer for $45 from Jaycar to track the temps:

and the next question would be: where do you mount the temp sensor
AVO do an intercooler - throttle body hose that has a point to clamp this temp sensor directly into.

Disclaimer: Modifying is contagious

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Speak to Shane @ SMC Tyres, Unit 6/385 Sevenoaks St Beckenham WA 6107. Mobile 0413 128 087. Tell him Maddog sent you!

The spray nozzles i've gone with are 'micro mist' used for outdoor humidifying, they seem o.k. the pump is fairly high pressure.

I have a Defi thermocouple in the i/c to throttle body coupling.

I'm going to try to get it all installed this weekend, I'll post up the results if I have time.

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