When air gets sucked through the filter, it goes into the cool side of the turbo and is compressed (boost) before being pushed through pipes and into the engine. The boosted air combines with fuel and creates a bigger explosion than it would unboosted. The explosion pushes the pistons, which turns the crankshaft and out into the wheels. The exploded gases exit the engine via the hot side of the turbo. These gases spin a small turbine which is attached to a turbine in the cold side of the turbo. The faster the gases pass through the turbo, the faster new air is sucked into the other side of the turbo. This is what happens when you put your foot down.
Now. The problem is that there is one hell of a lot of heat created when the gases exit through the turbo. This heat transmits to the fresh air going through the turbo. Engines like cold air. The hotter it is the less efficient the combustion.
To overcome this, a cooler is added into the air pipework leading to the engine. This cools the air down. The cooler is relatively small and is mounted in the wing, just in front of the passenger wheel. When driving hard, upping the boost, in the summer, the cooler's efficiency is crap. The goal is to lower the air intake temperature to as near to the ambient temperature as possible. The average temperature of the air after it passes through the Wing Mounted Intercooler is 15 degrees C over ambient. However, this can often reach 60-70 degrees C over ambient
A Front Mounted Intercooler is 400% better at cooling. Since I fitted mine, the intake temperature sits at around 5 degrees C or less above ambient, and has never gone over 50 degrees C, regardless of ambient.
This allows the engine to run more boost safely. In fact, when you fit one, the boost usually rises a couple of PSI by itself.
Hope that gives you an idea.
