Intercooler Spray Squirter

Over the years we’ve covered lots of ways of triggering intercooler water sprays. But here’s probably the simplest and most effective. It’s also smart, because it relies for its brains on you, the driver. After all, you know whether you’re driving hard, you know whether the day is hot or cold – and you (often) know how much performance you’re going to want in the next few minutes.

So let’s put control of the intercooler spray in your hands, via a dash-mounted pushbutton. You press the button and the intercooler water pump sprays. Easy, huh?

But let’s add the killer trick.

If you press the button once, the spray automatically switches on for (say) 5 seconds. But if you press the button twice, the spray stays on for 10 seconds! A quick triple press - and the spray squirts for 15 seconds!

So what the system does is to monitor how many times the pushbutton is pressed and then spray accordingly.

You can give the button one press to get rid of heat soak after re-starting a hot car. You can give the button two presses when about to perform an overtaking move. Or, stopped at the traffic lights and lining-up someone in the next lane, you can give the button three presses!

How Long?

During the initial set-up, you can configure a ‘one button press’ to be any time length from 1 second upwards.

So if you have a small volume spray nozzle and a pretty large tank, you might make the one-button-press 30 seconds long. Then the nozzle will spray in increments of 30 seconds – one press for 30 seconds, two presses for 60 seconds, and so on.

On the other hand, if your intercooler spray really splashes the water around, you might make the one-button-press 5 seconds. Then you can have a spray period of 5 seconds, 10 seconds, 15 seconds, etc.

Change Your Mind?

But what happens if you press the button four times – and then the noise of the pump tells you the tank is empty? Not a problem – just press the button for a single long push. That cancels the pump.

eLabtronics Timer Module

The Intercooler Spray Squirter uses as its control system a pre-built electronic module – the eLabtronics Timer. This costs AUD$59 and is available from the AutoSpeed Shop. You’ll also need a box – Performance Modules Box - Bulkhead - Black is suitable. Finally, you’ll need a pushbutton. Any normally-open pushbutton is suitable, including low current switches.

The module has only four wiring connections, so it is easy to wire into place. The module can directly drive the pump, so no relay is needed.

If you don’t already have them, you’ll also need a suitable pump and spray nozzle. A good quality windscreen washer pump and brass misting nozzle are suitable. The reservoir can be your existing windscreen washer bottle, or you can fit a new tank.

Wiring

The Spray Squirter needs only four connections.

An ignition-switched source is used to feed 12V to the positive terminal of the module. (“Ignition switched” means it turns off when the ignition switch is turned off. The cigarette lighter usually has a 12V supply of this sort.)

This 12V source also connects to the ‘In’ terminal of the module via a normally open pushbutton. (“Normally open” means it’s open until you press it!)

The negative (-) terminal of the module connects to chassis ground (or the negative terminal of the battery).

The spray pump is wired between the ‘Out’ terminal of the module and ground, with the positive side of the pump going to the module.

DIP Switch and Pots

On the board there’s a DIP switch to configure the module for different functions. Orientate the board so that the terminal strip is on the right and then use a ballpoint pen or a small screwdriver to set the switches so that they look like this:

X		X	X
	X

Now it’s time to set the length of time that one button press will operate the Spray Squirter. You can set this anywhere between 1 second and 1 hour (but I reckon 1 hour might be a bit excessive!).

Again orientate the board so that the terminal strip is on the right. Use small flat-bladed screwdriver to rotate the bottom pot anti-clockwise at least 15 turns, or until it can be heard clicking. (Why so many turns? Multi-turn pots like the ones fitted don’t have clear ‘end stops’, so to make sure you’ve adjusted the pot as far as possible to the minimum value, turn it lots of times!)

Then do the same for the upper pot – rotate it anti-clockwise at least 15 turns, or until it can be heard clicking. OK, now both pots have been adjusted to give the shortest possible time. Now turn the upper pot clockwise 4 full turns. The spray time with one push of the button will now be about 5 seconds.

If you’ve wired the system up as shown above, you can now test it. (If you don’t want water everywhere, you can do the testing with the pump disconnected!) Press the button once and the on-board LED will start flashing. (If the pump is connected, the spray should also start operating.) After the timed period has elapsed, the LED and pump will stop operating. To let you judge the time, the LED flashes twice per second.

If you want a shorter time, rotate the upper pot anti-clockwise. If you want a longer time, rotate the upper pot clockwise. If at any stage you want to cancel the spray, keep your finger on the button for a few seconds.

If in operation you find that you want to adjust the spray period, it’s as simple as altering the position of the upper pot. By rotating this pot you can set the time anywhere between 0 and 60 seconds. (As shown here, the other pot sets minutes rather than seconds.) Note: when setting the spray time, you should get an assistant to watch the spray nozzle itself – some pumps take a few seconds to get going.

High Power Pump? If you run a very high power pump (ie much higher power than typical windscreen washer pump), you may need a heatsink on the MOSFET – check to see if this component gets hot when the pump is running. See the end of eLabtronics Timer for details on fitting a heatsink.

Installation

With the set-up complete, install the board in its box and then mount the box somewhere convenient – eg up under the dash. Insulate all wiring joins and keep the wiring neat and tidy with cable ties.

If you want a dashboard indication that the pump is running, you can carefully unsolder the LED and extend its wires so that the LED can be mounted within the driver’s line of sight (hard), or wire a 12V pilot light in parallel with the pump (easy, and shown in this diagram).

Conclusion

The Intercooler Spray Squirter is versatile, easy to control and can make a major difference to intake air temps, all without using any more water than is required.

The Timer is available fully built and tested from the AutoSpeed Shop.

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