An intercooler cools the air coming out of a turbocharger or supercharger before it enters the engine. Compressing air heats it up, and hot air is less dense and more likely to cause knock. By bringing the temperature back down, the intercooler packs more oxygen into each cylinder and lets the engine run more boost safely, so it makes more power and stays more consistent run after run.
Why compressed air needs cooling
A turbo or supercharger raises the pressure of the intake air, and compressing a gas raises its temperature. Without cooling, much of the density gain from boost is lost to heat, and hot intake air raises the risk of detonation, which forces the engine computer to pull ignition timing and cost power. Cooler air means more power from the same boost and a larger safety margin.
Types of intercooler
- Air-to-air: the charge air passes through a radiator-like core cooled by outside air. Front-mount intercoolers sit behind the bumper; top-mount intercoolers sit on top of the engine and are fed by a hood scoop, as on many turbocharged Subaru WRX and STI models. Simple and reliable, but the long piping adds volume.
- Air-to-water (liquid-to-air): a compact core cooled by coolant, with its own pump and a separate heat exchanger at the front of the car. It keeps the charge air path short, which is why it is common under positive-displacement (Roots and twin-screw) superchargers and on many modern factory turbo engines.
What to look for
- Core size and design: a bigger core cools better but can add pressure drop and piping volume.
- Pressure drop: a good intercooler cools the air without losing much boost through the core.
- Heat soak: in traffic or on repeated runs, intercoolers heat up; airflow, and for air-to-water systems the coolant circuit, decide how quickly they recover.
- Fit: an intercooler is part of the whole induction system, so it must match the kit, ducting and sensor locations it is designed for.
Intercoolers in supercharger kits
Centrifugal supercharger kits like the East Coast Supercharging (ECS) Paxton NOVI kits we carry include an intercooler and ducting as part of the kit. For C7 Corvette owners upgrading an ECS-based system, the ECS C7 Horizontal Intercooler, which ECS rates for 1000 HP, is $988.90 on its own. Browse the kits on our supercharger kits by platform page, and read supercharger vs turbo or what does a supercharger do? for the bigger picture.
Do diesels have intercoolers?
Yes. Turbo diesels such as the Cummins in Ram trucks use an air-to-air intercooler, often called a charge air cooler, in front of the radiator. Upgraded turbos, like the Fleece VGT Cheetah units on our 6.7 Cummins turbo page, rely on it to keep intake temperatures in check.
More guides: twin-screw vs Roots · what does a blow-off valve do? · what does a wastegate do? · front mount vs top mount intercooler · how long an intercooler lasts.
Trouble codes: P0127 Intake Air Temp Too High · all OBD2 codes.
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