Most turbocharged petrol and diesel car engines use intercoolers – radiators that cool the air after it has been compressed by the turbo. An intercooler has twin benefits of providing more power (the intake charge is cooler and therefore denser) and in the case of petrol engines, reducing the chance of detonation.

The tiny droplet size resulting from the use of the "espresso" pump and a Spraying Systems nozzle can be seen here. In this case, the nozzle is aimed forwards and the car drives into the cloud of water droplets. These very effectively cool a front-mounted intercooler and as a bonus also help cool the other radiators!

In many cases though, the intercooler is too small for best performance – especially in a hot country like Australia. This can be greatly improved by adding a water spray – the small droplets evaporate on the core, lowering its temperature.

How do you trigger the spray? Many
people use a boost pressure switch – but this wastes lots of water because the spray operates even when the intercooler is cool. Another approach is to use a temperature switch but this also wastes a huge amount of water because it doesn’t take into account heat-soak (eg, when the car is stopped for a long time in traffic), where a simple temperature switch can continue to run the spray until the tank is emptied. Also, both types of switch cannot easily be adjusted for their switch-on points.