Intercooler
A heat exchanger that cools compressed intake air from a turbocharger or supercharger before it enters the engine, increasing power and efficiency.
An intercooler (or charge air cooler) is a radiator-like heat exchanger used in vehicles equipped with forced induction systems, such as turbochargers or superchargers. When a turbocharger compresses incoming air to increase engine power, the physical compression process heats the air up significantly. Hot air is less dense and contains less oxygen, which can cause engine knock (detonation) and reduce combustion efficiency.
The intercooler is positioned between the turbocharger and the engine intake manifold. As the hot, compressed air flows through the intercooler, it is cooled by either ambient air passing through its fins (air-to-air) or by engine coolant (air-to-water). Cooling the air makes it denser and richer in oxygen, allowing the engine to burn more fuel and generate significantly more horsepower and torque.
Intercoolers can suffer from external fin damage, oil accumulation from PCV systems, or air leaks. Symptoms of an intercooler leak include a hissing sound under acceleration, reduced boost pressure, loss of engine power, and black smoke from the exhaust in diesel vehicles.