Heat is the arch-enemy of any motor. This is the main reason why intercoolers are a vital part of any turbo kit. An intercooler is essentially a radiator tuned for high-volume flow rates and the increasing density of the charge as it cools. Lower air intake temperatures are safer for the motor, making air-to-air or air-to-liquid intercoolers vitally important. It is also crucial that they are mounted, so as to maximize air flow and promote efficient cooling.
The range of forced induction and the presence of spent exhaust gasses cause motors to generate enormous amounts of heat. An intercooler uses ambient air temperatures in the front of the moving vehicle to chill a core. The intake air temperature drops as the forced air from the turbo passes through this core. The resulting compressed air allows more air volume to enter the motor. The more air you can compress while keeping it at the same relative PSI, the more air you can force into your motor-providing more power and efficiency.
A cooler engine will exhibit extended longevity and generate more horsepower. In addition, an intercooler protects against the expanding or warping of internal motor parts, which...