If you’re going to be producing horsepower—thanks to awesome turbocharger—you have to make sure it’s besties with the intercooler. Turbos are their most efficient when frosty compressed air makes its way to the engine. The colder and more compressed you can make the air, that much more oxygen the motor will receive, and in the end, produce more power.
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Intercoolers in themselves are actually quite a simple idea. They take hot air and convert it to colder air, which increases the density and raises oxygen levels for the motor to combust. There are two different intercooler types and a few ways of setting them up, but they all perform the same basic function.
The first intercooler setup is the air-to-air. These are the least complex setup; meaning they essentially act as a radiator for your turbo. Instead of circulating coolant and dropping the engine temp, they circulate warm air and make it cool. You will see the air-to-air intercooler at the front of performance cars for the main fact that they need constant air to cool the fins on the intercooler, and positioning it in front the car Mad Max style works great because it can utilize infinite air present in the atmosphere for cooling.
However, they also take up more room, which means again you’re probably going to have to bring it to the front of the car (or on top of the motor like Subaru); because, well, they take up large amounts of surface area. With the compressed air of the turbo circulating through the fins and network of piping, this in turn cools the air before reaching the engine. Air-to-air intercoolers have the benefit of also being lightweight since they don’t require the additional piping, heat exchanger, and water pump of air-to-water intercoolers.
Air-to-water intercoolers are much more complex than the air-to-air since they require more plumbing, a water pump, and more steps to get the proper setup for your turbocharged car. Since they can hold as much as seven to eight gallons of water per system, weight adds up quickly. But, they can be installed almost anywhere on the car—which is great for mid and rear engine cars—and can cool down air more effectively.
Air to liquid intercoolers can also use the added benefit of ice to cool it even further by circulating liquid through a container filled with ice. There are plenty of specialty products for these applications. You can even find vendors who will sell you dry ice intercoolers for keeping your turbo air extremely frosty, though it’s certainly not convenient.
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One of the problems with water intercoolers is that if you’re running your engine hard for an extended period of time, they can become heat-soaked since the hot air encapsulates the entire surface area of the intercooler. They become overheated, essentially making them inefficient. The solution to this is either a heat exchanger, or using a methanol injection systems to super cool the water right after it passes through the intercooler, making sure it is cold once it reaches the engine. Both add complexity and more pieces to the intercooling puzzle, but they work effectively and judiciously.
There’s a science to setting up a proper intercooler setup, which is why top turbocharger specialists command a premium for their work. You want to make sure you can maximize pressure and minimize heat transfer without reducing pressure and introducing more lag. This is why figuring out the most efficient setup for your particular vehicle is a top priority. With Intercoolers there are plenty of ways to skin a cat, but once you know the basics you'll have a great first step in choosing the right setup for your budget and build needs.