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.
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.
