Intercooler Nozzle Spray

I do know a little about cars but i don't claim to be an expert. I was just wanting some info on the nozzle spray. what does it do, what does it spray? how much. Do all intercoolers need this?

Well as Im sure you know the job of an intercooler is to cool the air between the turbo/SC and the inlet manifold.
The more the Air is cooled the more of it can be crammed into the combustion chamber and the bigger the bang.

Water is a very efficant heat conductor, by spraying it on an intercooler you increase its ablity to cool the air passing through it, as more heat is conducted into the air passing over it.
The highly strung engines in cars like the STi WRX (where the water sprayer first made an apreance in a production car) and the EVO have a lot of heat transfer from the Turbo to the intake air, and this in turn heats up the intercooler to a point where its efficancy is decreased.
However it only happens at high RPM when full boost is reached, and so a water sprayer is used to keep it all cool.

Idealy the cars would you use a large enough intercooler exposed to enough cold outside air that it would not need a water spayer, but design limitations prevent this, so the water spayer is used as a "fix".

Very few factory turbo charged cars need one, but its one of those things that can't hurt.

so under normal conditions i would never really need to use the spray? What would be an indication to use it? the engine running hot?

The ECU in the STi automaticly use's when a set boost level is reached, but some ppl put a throttle switch on them so it sprays at full throttle. (which normaly means your running full boost anyway).
And some ppl that drag race them switch them so they run all the way down the 1/4.

But the tank only holds a few litres, and will only spray for a minute or so, so you don't want it comeing on all the time.

I assume the set up in the EVO will work similar to the STi, and be switched of boost pressure.


The engine running hot will not be caused by the intercooler getting to hot, the increase in air temp will not be enough to cause the engine to over heat.

ok, that makes sense. thanks a lot. so it sprays automatically. Yeah, the evo has a switch that sprays when you press it. I guess you could just do it if you feel the need to spray it. thanks though

I'm pretty sure u can either set the spray to be controlled by the ECU or u can set it to manual and for example u could be at the lights and give it a good spray before u race someone etc etc.