A Charge Air Cooler (CAC) is a type of air-to-air heat exchanger used in turbocharged diesel engines for trucks, buses, and heavy equipment. Its main job is to cool the compressed air from the turbocharger before it enters the engine’s intake manifold.
The turbocharger compresses the intake air, increasing its pressure and temperature. Hot air is less dense, which reduces the amount of oxygen available for combustion. The hot, pressurized air flows through the Charge Air Cooler, which cools it using ambient air. This cooling increases air density, allowing more oxygen into the cylinders for better combustion. Cooler, denser air results in more efficient fuel burn, improving power, torque, and reducing emissions.
Diesel CAC
A Charge Air Cooler (CAC) is essential on a diesel engine, especially in turbocharged systems for several critical performance, efficiency, and emissions reasons.
How Compression Ignition Works:
- Air Intake - Only air (not fuel) is drawn into the cylinder during the intake stroke.
- Compression Stroke - The piston compresses the air to a very high pressure (typically 16:1 to 22:1 compression ratio). This high compression raises the temperature of the air to 500–700°C (932–1292°F).
- Fuel Injection - Near the top of the compression stroke (TDC), diesel fuel is injected directly into the hot compressed air. Because the air is so hot, the fuel auto-ignites without any spark.
- Power Stroke - The rapid combustion pushes the piston down producing mechanical power.
- Exhaust Stroke - Burnt gases are expelled from the cylinder, and the cycle repeats. The more air (oxygen) you can pack into the cylinder, the more fuel you can burn efficiently. Without a CAC, turbocharged air is too hot to be used effectively.
Charged Air Cooler
Why do people call a “charge air cooler”, a “charged air cooler”?
That’s a great question and a very common point of confusion.
The correct term is Charge Air Cooler (CAC). The term "charge air" refers to the air that has been compressed by a turbocharger. Hence, a Charge Air Cooler is a device that cools the compressed (charged) air before it enters the engine.
-
Grammar Confusion:
- “Charged” sounds like the past tense of a verb ("air that has been charged").
- People assume the air is “charged,” and the device cools it, hence “charged air cooler.”
- While technically the air has been charged, the correct noun form is “charge air.”
-
Similar Sound:
- “Charge air” and “charged air” sound very similar in speech, especially quickly or with accents.
- This leads to mishearing and mislabelling.
-
Lack of Familiarity:
- "Charge air" is an engineering-specific term.
- Non-specialists (drivers, mechanics, and general public) might not know the correct phrasing and say what sounds logical to them.
CAC Cooler
Dura-Lite™ is a well-known Canadian manufacturer specializing in heavy-duty CAC Coolers for diesel-powered trucks, buses, and industrial equipment. Dura-Lite CACs are widely respected for their durability, performance, and leak resistance, especially in demanding environments like long-haul trucking and off-road applications.
The Dura-Lite Evolution® CAC Cooler is a premium heavy-duty intercooler with advanced engineering designed to withstand the harshest conditions and dramatically reduce failures.
Our Evolution charge air coolers are engineered to eliminate the most common charge air cooler failure modes with innovative design and rigorous testing. Our warranty, construction quality, and performance have made us an industry leader that delivers reliable cooling, fuel savings, and long-term peace of mind.
Dura-Lite has a proven track record for more than 30-years which includes a less than 1% warranty return rate, trusted across OEM Truck and Engine Dealers and major fleets.
Demand Excellence! Demand Performance! Demand Quality! Demand Dura-Lite!