Nothing else screams ‘performance’ quite like a shiny front-mounted intercooler peaking out from behind a car’s radiator grille. It’s an immediate giveaway that the vehicle in question is packing more power than stock, and it’ll certainly win the owner some style points at a meet or show.

We can all agree that intercoolers look, well, cool. Pardon the pun. But beyond that, just how much an impact can they have on performance? How do they work? And is it worth switching out your stock intercooler for a larger aftermarket equivalent?

We’re going to separate fact from fiction in this guide, dispelling some common myths and telling you everything you need to know about intercoolers.

What is an intercooler?

Fitted exclusively to forced induction cars - those with turbochargers or superchargers - intercoolers have one job to do: cool the air that flows from the turbo or supercharger before it enters the engine.

Forced induction systems work by ‘forcing’ more air into the engine, allowing it to produce more power and operate more efficiently. But the colder that air is, the better. Cold air is more dense than hot air because each molecule is packed closer together - so the cooler the air going into your engine, the greater the overall airflow. And, as we know, more air means more power (provided the fuel and ignition systems can keep up, of course).

The benefits don’t end there. By cooling the air flowing into the engine, intercoolers can also help keep engine temps down, improving reliability and even reducing exhaust emissions in some cases.

It’s for these reasons that most forced induction engines nowadays come with an intercooler already fitted, albeit a relatively small one. There are multiple reasons why switching to a larger one can be beneficial, but we’ll get to them later on.

How do intercoolers work?

Intercoolers are pretty simple devices. Mounted either at the front, side or top of the engine bay, they’re connected to the engine and the turbo (or supercharger) via a series of pipes and clamps.

The hot air kicked out by the turbo or supercharger is fed through those pipes and into the intercooler unit itself, before being cooled and then fed back into the intake manifold (and in turn, into the engine).

Just like a radiator, intercoolers use a combination of fins and plates to dissipate heat. As you drive along, air flows through these fins and plates, cooling them and, consequently, cooling the air passing through the inside of the intercooler.

The principle is much the same as a radiator or an oil cooler, but for air molecules instead of coolant or oil.

Because intercoolers rely on air flowing across them to work best, the more airflow you can direct to your intercooler, the more effective it will be. That’s why you so often see modified cars with large, front-mounted intercoolers, often with the bumper cut away to accommodate them. With no plastic or metal in the way to disrupt the airflow, the intercooler can do its job more efficiently, resulting in improved performance.

The two types of intercooler explained

There are two types of intercooler you need to know about: air-to-air and air-to-water. While the former uses air flowing across the intercooler unit to cool the air from your turbo or supercharger (as we’ve detailed above), the latter uses coolant, just like a radiator.

Air-to-air intercoolers are the default choice for 99% of builds because of their reduced complexity, more attainable price point and reduced weight. Provided you can position the intercooler at the front of the car where plenty of air will flow across it, an air-to-air intercooler will likely be your best bet.

If you have a rear-engined car or a more specialised vehicle where air flow over an intercooler is likely to be limited, an air-to-water intercooler starts to make a lot more sense. Not only do these systems offer more consistent, more stable cooling performance at all speeds, they also don’t rely on constant airflow to work at their best.

Bottom line? Unless you own a rear-engined vehicle, an air-to-air intercooler is almost certainly the best option. Cheap, effective and lightweight, they’re used on everything from high-performance road cars through to the latest and greatest racing machinery.

Different intercooler mounting locations explained

There are multiple different ways to mount an intercooler, too. From the factory, many turbocharged vehicles came with side-mounted intercoolers - relatively compact units tucked just ahead of one of the front wheels. Nissan used this layout for many of its ‘90s performance cars, like the Silvia and Skyline. The advantage of this design is that it still allows air to flow over the radiator uninhibited, but the small size of the intercooler means that it can become a performance bottleneck as the boost level is increased.

Next there’s the top-mounted intercooler, famously employed by road-going rally cars like the Subaru Impreza WRX STI, Toyota Celica GT-Four and Nissan Pulsar GTI-R. You’ll notice all three of these cars have one thing in common: prominent bonnet scoops or vents. That’s because the intercooler is mounted atop the engine, and the vents are required in order to maximise airflow - they’re not just there for show. The advantages of this layout are shorter pipework (which can reduce lag) and reduced risk of damage from stones and other debris, hence why it was chosen for all those rally homologation specials. The downsides are that it necessitates the use of a vented bonnet, heat soak can be an issue, and the size of the intercooler itself is also limited - just like with side-mount intercoolers.

Finally, front-mounted intercoolers - the go-to choice for most modified cars. Why? Because there’s enough space up front on most cars to fit a larger intercooler, which cools the air more effectively and helps the engine produce more power. As well as being the optimal choice for performance, they look the part too. The only real downside is that airflow to the radiator is restricted slightly because the intercooler is mounted in front of it. But if you’re planning on upping the power of your engine significantly, ditching your stock radiator in favour of an aftermarket one is a wise move anyway.

The impact of intercoolers on performance

This is the question most people want an answer to: just how much extra power could your engine produce if you fit a larger intercooler?

With so many different variables to factor in, it’s impossible to answer this question accurately. If you fit a larger intercooler and get your car remapped to take advantage of it, you might see an increase of 5 hp. Some cars - particularly those with tiny factory-fit intercoolers - might experience a more significant bump of 10-15 hp.

Basically, it depends on the car you drive, what other mods you’ve fitted and which intercooler kit you go for. Either way, an intercooler on its own isn’t going to deliver a significant power increase. However, if you combine it with fuel system and exhaust upgrades and turn up the boost, the performance improvements can be much more significant - up to 50 hp or more in some cases!

So, should I upgrade my intercooler?

If you ask us, the benefits massively outweigh the downsides. But you can judge for yourself…

Pros 

• Increased horsepower and torque, particularly when fitted in combination with supporting mods (like a larger fuel pump, high-performance spark plugs, a free-flowing exhaust system and an ECU tune)
• Improved reliability
• Reduced emissions and fuel consumption in some cases
• Low cost per horsepower in comparison to many other upgrades
• Added aggression and style points!

Cons

• You may have to trim or remove some OEM parts in order to fit a front-mount intercooler
• Larger, more prominent intercoolers are more prone to suffering damage from stones and debris
• Fitting an intercooler that’s too large can negatively impact response and cause turbo lag

Choosing the right intercooler kit for your car

As we’ve touched on above, bigger isn’t always better when it comes to intercoolers. Choosing a unit that’s paired well to the size of your engine and turbocharger (or supercharger) is key to maximise response without sacrificing power.

The best option is to go for an intercooler kit from a brand like Forge Motorsport. Companies like Forge do the hard work for you, carrying out all the R&D that’s required to work out which size of intercooler is the best fit for your car. They take everything into account, from maximising performance and response to ease of installation, weight and price. Not to mention, they come with everything you need to get the intercooler fitted, from pipework through to hose clamps, brackets and more.

Intrigued? Check out our complete range of intercooler kits online today, all of which are manufactured by top brands like Forge to suit a range of cars, from Audis and BMWs to Fords, Vauxhalls and more.