One of man’s desires is speed. Every once in a while you wished you could live the fast life: easy money and fast cars. With the introduction of the intercooler, car manufacturers gave you at least one of these things. The intercooler is a revolutionary work of art: technology plus craftsmanship. Many modern cars now use intercoolers, the rest you can have it installed into one. Once used mainly for rally cars, the reputation of intercoolers has skyrocketed recently due to the power it gives to an engine that can only be equated to the cost of having one installed.
Cars that do not come equipped with one can buy intercooler kits, such as the one in fig. 1. However, they do not come cheap, the price tag on one of these upgrades can start from a few hundred dollars to several thousands. Still, more and more racing parts manufacturers are making intercoolers which means that the market for intercoolers continues to rise. People who want to add a boost of speed to their cars and has the money to spend would just have one installed without knowing anything about intercoolers.
Its popularity and high demand require that we spend some time knowing about intercoolers: the technology behind it, its advantages and disadvantages, types, etc. An intercooler is a heat exchanger which cools the compressed air feeding the engines of cars equipped with a turbocompressor (Denso). It is an air-to-air or air-to-liquid heat exchange device used only on turbocharged and supercharged internal combustion engines to improve their volumetric efficiency by increasing intake air charge density through isochoric cooling.
is designed to remove heat from the compressed air coming from the supercharger (or turbo) before it enters the engine’s induction system. An intercooler works just lie a radiator – air is cooled by fins, bars, louvres, and plates inside the intercooler that are cooler than the compressed air coming from the supercharger. The reduction in air temperature increases the density of the air (Superchargers).
A decrease in air intake temperature provides a denser intake charge to the engine and allows you to run more boost on a given octane of fuel before detonation occurs which consequently increases your engine’s ability to make more horsepower and torque. (Wikipedia, 2007a) An intercooler will do two things – it will lower the temperature of the intake air and at the same time, cause a slight drop in boost pressure. The latter comes from the restriction to flow caused by the intercooler.
Some restriction is unavoidable because the flow through an efficient intercooler core needs to be turbulent if a lot of the air is to come in contact with the heat exchanger surfaces. However, if the pressure drop is too high, power will suffer. A pressure drop of 1-2 psi can be considered acceptable if it is accompanied by good intercooler efficiency. Intercooler efficiency is a measurement of how effective the intercooler is at reducing the inlet air temperature. Typical good intercoolers are around 70 percent efficient.
No intercooler has ever achieved 100 percent efficiency (Edgar). If made to choose between having an intercooler installed or not, the answer all depends on the design of the intercooler, and there are two factors involved; efficiency and the flow restriction created by the presence of the intercooler (BellIntercoolers). These problems are easily addressed, that is why many people rather have intercoolers if they can afford one. The recent rise of the intercooler’s popularity is mostly attributed to the benefits car owners experience from intercooling.
The most significant of this is that intercooling increases the detonation – process of unstable combustion, where the flame front does not move progressively through the combustion chamber – threshold because of the cooler air charge, meaning you can run more ignition advance for higher performance, or run lower octane fuel before experiencing detonation. This makes intercoolers very desirable for those looking to get the most out of their street vehicles on gasoline. The cooler air also allows your engine to run slightly cooler, reducing the chances of overheating.
Intercoolers also enable your engine to produce more horsepower because of the denser air charge being delivered to the engine’s combustion chamber. With its advantages, car owners using intercoolers must also suffer a trade off for power. The power intercoolers give come at a price, aside from the expensive cost of having one installed, owners must also take into consideration that intercoolers create some internal drag causing a slight reduction in boost, and can also cause the engine to run lean due to the denser air charge (Superchargers).
Also, oftentimes a pressure loss results because an intercooler fin or louver obstructs the air flowing into the engine, however, considering the benefits gained by having a good quality one fitted and the minimal loss of airflow inherent in a well designed intercooler the loss seems to be of little importance (Torquecars). In installing or upgrading an intercooler, the position is critical. Since an intercooler is effectively a radiator that allows the intake air charge to be cooled before it gets into the engine, it is ideal to mount an intercooler in front of the radiator so that it gets all the cold air hitting it.
However, there are two mostly used positions of an intercooler, they are the front mount and the top mount. Both have their own advantages. Top mounted intercoolers (Fig. 2) suck air in through the bonnet. The advantage of this is that when the car is stationary it is actually being hit by warm air coming from the engine bay which actually improve economy as you are able to burn less fuel because the air is warmer especially during traffic (Torquecars).