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Intercooling

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Forced induction systems (ie turbocharged and supercharged) force additional air mass into the engine. This increases the efficiency of the engine and allows more fuel to be burned (and hence more power is made). As a by-product of the compression process, the air entering the engine gains heat. An excessively hot intake charge reduces the performance gains due to decreased air density. The extra heat may also cause detonation, excessive wear and heat damage to the engine block.

An intercooler is an air-to-air or air-to-liquid heat exchange device used to reduce the intake air heat. This increases the air density, providing increased efficiency from the forced induction system. It also reduces the likelihood of all the prior mentioned problems.

More info on Wikipedia.
Companies such as PWR make the required components.

Air-to-Air

Air-to-air intercoolers transfer the heat directly to the atmosphere. The heat exchanger in these systems is similar to a radiator, whereby the hot air passes through and transfers heat to metal tubes. The tubes have fins attached, which then transfer the heat to the atmosphere. They are placed in a direct air stream to achieve the best cooling results and can be improved even further with a fine water mist.

Air-to-air intercoolers are a simple and cheap system, which makes them very popular. However, because they need to be located in a direct air stream, they are vulnerable to damage from debris. Further to this, they are usually connected with long intake pipework, which increases lag and pressure losses.

Air-to-air intercoolers can be placed in a number of locations, such as the following.

Front Mount

The intercooler is located at the front of the vehicle, often between the grille and the radiator. A large amount of cool air is available in this location, which makes the intercooler rather effective. It is also easy to fit a large intercooler in at this location.

It is not without its drawbacks though. The intake pipework to this location will be rather long. It is also at the very front of the vehicle, making it highly susceptible to damage. In some cases, the intercooler can cause overheating issues to the engine, as it is in effect ‘blocking’ the radiator and making the ‘cool’ air that it uses hotter. This can also be a problem with spotlights and other items that are in front of the radiator.

Example Installations

Top Mount

The intercooler is located above the engine. A bonnet scoop is required to feed air to the intercooler. Often, a body lift is required to fit the intercooler between the engine and the bonnet. This system has the advantage of short pipework, due to its proximity to the engine. It is also rather safe from debris (compared to front mount).

It also has some negative aspects though. Due to its close proximity to the engine, it can often suffer from heat soak (the intercooler becomes hot and has a reduced capacity). The size of a top mount intercooler is often smaller than a front mount, due to space constraints and bonnet scoop size etc. The air flow is often not as great either, also reducing the efficiency.

Example Installations

None found.

Side Mount

Not the most practical system in a 4wd, the intercooler is located at the front corners of the vehicle, ie underneath the headlights or in the wheel well. These intercoolers are usually not very big, due to space constraints. This sometimes necessitates the need for 2 or more small intercoolers, which require a large amount of pipework. Due to this and also the vulnerability of an intercooler in such a location, it is not recommended for your Patrol.

Hybrid Mount

This is the idea of locating an intercooler in an unusual location. For example, it could be located above a battery tray and have air ducted from the radiator and out through a guard vent. This possibility of a hybrid system is only limited by your imagination, however its simplicity, safety, benefits and cost effectiveness should questioned.

Water-to-Air

Water-to-air intercoolers transfer the intake heat to a liquid medium (ie water). In a normal system, the intake air passes through a metal barrel cooler. Within these, the air is pushed through tubes which have fins attached. Water (or similar liquid) flows around the tubes and fins, which removes the heat. The hot water is then pumped to a conventional radiator elsewhere in the vehicle, where the heat is removed to the atmosphere.

These systems are rather complex and costly, due to the amount of components required (ie barrel cooler, pump and radiator as a minimum. Possibly a reservoir or cooling fan, depending on complexity of the individual system). This also means there are more things to go wrong, and all the components are dependent upon electricity.

The system does have a lot of advantages though. They are highly effective at cooling, and in extreme cases can be improved with the use of ice in a reservoir. The barrel can also be located in close proximity to the engine/intake, reducing lag due to long pipework. This also means it is safer from damage. Similarly, the radiator can be located in any location, even those not with direct airflow, as an electric fan can be used.

Example Installations