Understanding air to air intercoolers

Engine Performance Parts improve supercharger performance...

I am compiling a guide on information on how to pick the exact engine performance parts to fit your target power requirements. Basically I want to eliminate all the guess work out of tuning and save you some money from having to do things over and over again.

While I was doing research for 'buying the right intercooler' I got lost, honestly.

There are two types of information you will find out there:

1-One class of articles is written by engineers talking about pressure differentials, thermal efficiencies, enthalpy and multi variable equations that are very remotely related to flow, horsepower, torque, supercharger rpm or other things that we KNOW that we can use as an input to our equations. (Basically this science needs to be translated to layman's terms)

2-The other class is a group of random trial and error advice by enthusiasts, press releases and other materials that you find online.

Here's what we do know:

First let's talk about how intercoolers work. There is some debate about whether the intercooler is like a heat sink whose function is to absorb thermal energy from the incoming air to prevent the heat from reaching the engine, or whether the intercooler is like a radiator, where the air flow over the intercooler is responsible for extracting heat from the inlet air charge.

The true answer is both are correct...

The air running through the intercooler spends very little time inside the intercooler and slowing it down for more thermal exchange (like we would coolant in the radiator) would mean preventing air from reaching the engine which is a restriction on power. Because the air spends little time in the intercooler, the intercooler usually has multiple passages, internal ribs, and fins inside of it to maximize the surface area contact between the intercooler aluminum and the compressed air molecules. In this sense, the overall volume of the intercooler, and the overall surface area of its internal surfaces are like a heat sink that absorbs the heat energy out of the compressed air. In this aspect it makes sense that the larger our intercooler, the better. Furthermore it also makes sense, that the more complex and intricate the internal passages of our core, the more heat we will be able to extract out of the charge air. Of course the flipside of this is that very complex internal passages can create turbulence and restrict airflow so ultimately there is a balance in good design

between internal complexity and flow capacity.

When we start out, the intercooler is cold, and with our first power run, as the hot compressed air runs through the intercooler, the heat is transferred to our heat sink (which is the intercooler) and nice cool air is left to enter the engine. After the first run, the intercooler is warm; and if we were to make a second power run back to back, the intercooler will not be able to SINK much heat because it is already somewhat heated.

This is where the intercooler as a radiator comes in, the heat that was transferred from the air to the intercooler core, needs to be taken away either by cross flowing air in an air to air intercooler, or by cooling fluid in an air to water intercooler, or even by an ice-water bath for drag racing applications. Without harvesting the heat that the intercooler has absorbed out of the compressed air, the intercooler will heat up run after run until its temperature is the same as the compressed air heating it. At this point there is no temperature difference between the air and the intercooler core and we can no longer SINK any heat.

Some cars have their intercoolers located under the car's hood (like the Mazda Sentia / 626). In this kind of installation the intercooler is mostly a heat sink and will be used for a few passes till it soaks, once it soaks it needs to be left to cool till it returns to under hood temperatures before it can be effective again as an intercooler. From this we gather, that any intercooler no matter how small, or poorly placed is better than no intercooler because at least for that first power run it will potentially increase horsepower.

MORE AT: http://www.helium.com/items/1509590-intercooler-supercharger-turbocharger-air-to-air-aftercooler-charge-cooler?page=1