More commonly known as an intercooler, the charge air cooler is a device on forced induction cars which cools air going from the turbo/supercharger to the engine. Intercoolers are necessary because when air is compressed rapidly, as with forced induction, it will heat up. If you pumped this heated air directly into the engine the power gains would be severely limited and you would probably damage the engine.
The function of the intercooler is to absorb heat from the air flowing through and disperse that heat into the outside air so your engine receives cooler denser air. This in turn translates to the engine generating more power and staying within its operating temperature. This is why with almost all supercharged or turbocharged cars you will have some type of intercooler installed from the factory.
F82 M4 with custom powder coated CSF Top Mount Charge Air Cooler installed
Intercoolers come in two different configurations: air-to-air and air-to-liquid. There are advantages and drawbacks to both but on newer vehicles you will typically see air-to-liquid being used from the factory, whereas air-to-air you will generally find on older/aftermarket applications.
How an air-to-air intercooler works
Air-to-air intercoolers involve routing the air through veins inside the intercooler which are connected to metal fins which help absorb and then disperse heat into the outside air. It is a very simple design but it works well, doesn’t add much weight, and is very reliable because there are no moving parts.
The downsides to this system are that you need a bigger cooler the more heat you want to disperse, and the cooler needs to have access to a good amount of airflow, so you’re very limited in where and even if it can be mounted. The piping for this system is also much longer so you do get a bit of extra boost lag.
How an air-to-liquid intercooler works
Air-to-liquid intercoolers are more complex but more efficient. They are made up of three main parts, the cooler itself, a coolant pump, and a heat exchanger, plus some hoses to route all the liquid. With this setup you get a lot more flexibility in placing your intercooler core. Much like with your engine’s radiator, only the heat exchanger needs to be exposed to airflow. You also get improved response due to having minimal piping between the turbo/supercharger and the intake manifold. Most importantly you get the heat absorption capacity of all the coolant in the system vs having a giant aluminum core at the front of your car.
The main drawbacks of this system are more points of potential failure and increased weight. Coolant weighs quite a bit, over 9 lbs per gallon. A typical air-to-liquid system contains at least one gallon of coolant or more, and upgrading your core/heat exchanger means adding even more coolant. Therefore if you’re thinking about upgrading this type of system it is important not to go completely overboard and add excess weight and bulk to your car.
M4 with factory Charge Air Cooler installed
Typically the factory intercooler is perfectly sufficient for the vast majority of people. The factory air-to-liquid unit in the F8X M3/M4 is no exception. However, if you’re an enthusiast who is attentive to your vehicle’s capabilities you will have noticed that on very hot days or after consistent high speeds you will notice a drop in power, especially if you’re running extra boost or other performance parts. This loss of power is due to a condition called heat soak.
Heat soak occurs when the charged air heats up the intercooler rapidly to the point where it cannot remove the heat as quickly as it is generated. This can be caused by high ambient temperatures or long periods of aggressive driving. We’ve dyno tested modified M3s and M4s with the factory intercooler and have seen significant power loss even during successive dyno runs. Obviously for the driver who is looking to get the most out of the motor upgrading the stock unit is a must.
F82 M4 with custom powder coated CSF Top Mount Charge Air Cooler installed
Luckily, VF-Engineering recently partnered up with CSF to resolve the issue. The CSF Top Mount Charge Air Cooler for F8X BMW M3/M4 is the result of a collaboration between these two companies. VF-Engineering used their expertise in 3D imaging and air-flow analysis to design the biggest and most efficient intercooler core available. CSF then took those designs and made them a reality with their expert team of fabricators and master welders. For those of you unfamiliar with CSF they are one of the biggest names in automotive cooling. They are pioneers in cooling technology and have put countless hours of research and development into advancing even the smallest details of their radiators. They test every radiator they produce for leaks and do vibration, heat, and airflow testing on each batch. This German level of diligence means you can trust them to make only the best for your BMW.
CSF Top Mount Charge Air Cooler with Crinkle Black powder coat
The result of this collaboration between industry giants is an attractive design with superb functionality and reliability. With the CSF Top Mount Charge Air Cooler you get a 60% larger core and the world’s first S55 cooler made with cast endtanks for added durability (vs plastic on the OEM unit). This added volume translates to more coolant flowing around the intake air to absorb more of the heat. The same heat being absorbed by a larger amount of coolant means a lower overall temperature in the system. They even designed the flow of the core with efficiency in mind, opting for a dual-pass design which routes coolant over the charged air twice for added heat absorption of the same volume of coolant vs the OEM single-pass unit. To top it all off, the CSF Charge Air Cooler is backed by a lifetime warranty from CSF and is no harder to install than any OEM part due to CSF’s use of OEM connections and sensor ports. It is a truly plug and play design so you don’t have to worry about extra install costs and fabrication work.
Single-Pass (left) vs Dual-Pass (Right) radiators
When the CSF Charge Air Cooler is paired with a CSF heat exchanger the cooling efficiency is improved even further. In addition to being quite a bit bigger than the OEM unit, the CSF heat exchanger features all aluminum construction and the same dual-pass design as the charge air cooler. The increased overall size of the CSF heat exchanger gives excellent gains in cooling potential. Furthermore, like the charge air cooler, the CSF heat exchanger also comes with a lifetime warranty and is an easy plug-and-play install using factory mounting brackets and hose connections. It also includes a removable aluminum rock guard which CSF provides free of charge for those who wish to protect the fins and avoid potential damage.
CSF Heat Exchanger vs OEM unit
The overall effect of pairing these two components is a drastic drop in intake air temperature and more consistent performance over long periods of intense driving. With both pieces installed VF-Engineering reports gains of approximately 8 HP and 9 lb/ft of torque to the wheels on their modified test vehicle (improving from 487hp/509tq to 495hp/518tq), as well as drops in intake air temperature of up to 15°F (113°F down to 98°F) with ambient temps around 76-78°F.
The CSF Charge Air Cooler is available as a standalone product, or if you buy the package which includes the heat exchanger you can save yourself a couple hundred bucks over buying them separately. We recommend getting both if you would like to maximize cooling, but you will still see improvements when buying the unit alone.
Custom powder coated red (left) and Hydro-Dipped Carbon Fiber (right)
The CSF Air Cooler is available in Crinkle Black and Raw Aluminum for immediate order. If you’re looking for a bit more of a unique look, custom powder coating and other finishes are available. If you have any questions about this product or want to or want to inquire about a custom finished unit please contact us at [email protected] or call 714-582-3330 to speak to one of our Mod Experts.