An intercooler cools the intake air in a forced induction engine.
When the intake air is compressed its temperature rises, and an intercooler may be used to ensure the temperature does not reach a level which may cause reliability problems – eg detonation.
An intercooler (the silver component in the engine bay above, carrying the STi logo) will also ensure the intake air remains dense, maximising the effect of forced induction.
An intercooler is a heat exchanger which takes heat from the intake air. It may be cooled by air flow (air/air intercooler) or by water flow (water/air intercooler or chargecooler).
