To understand how to make a performance part, we first have to understand what makes the stock parts tick and where we can improve them, which is what we will be covering today! For those of you that are new to the boosted lifestyle, I feel that I should go over a few terms that will be thrown around frequently later in this blog.
Shown above on the right side. Intercooler : A basic heat exchanger. Air flows through the inside and is cooled by air flowing through the outside while you drive down the road. The same way a radiator works except with air inside instead of coolant.
The end tanks are what transfer the air from the piping to the core while the core is the actual heat exchanging portion. Shown front and center in the above image. As it is after the intercooler, the air has been cooled to make more power.
Shown above on the left side. The hot side piping must make its way all the way from the rear of the engine to the front of the car. This, however, is where the good things end. To start, the two rubber sections of the hot side are single ply.
These allow for good flexibility on install and to allow for engine movement but will start to expand on higher than stock boost levels, increasing boost lag and decreasing throttle response. In the image above, the main rubber section squishes under the small weight of the upper plastic section of the hot pipe.
The upper plastic section of the hot side has quite a few small radius bends, and a few areas where the pipe reduces in diameter severely, affecting the maximum flow and restricting the power of your 2. Anyways, on to the intercooler itself. First: make it bigger.
While thick is not the best for heat transfer efficiency, it will still help cool off the air better. Height is already more or less maxed out without cutting up the crash beam, but we should be able to make enough extra volume elsewhere to make a big difference.
Intercoolers are a delicate balancing act between cooling efficiency and pressure drop. Cores that cool extremely well usually have a larger pressure drop loss of pressure from inlet to outlet and vice versa. With the high fin density of the OEM intercooler, we can expect a relatively high-pressure drop psi would be my rough guess but pretty good cooling.
From early dyno testing on the CorkSport Short Ram Intakethe intercooler does a good job cooling but loses power on back to back dyno runs. Heatsoak is what happens when an intercooler is undersized or is not getting enough airflow, it heats up and is no longer able to cool the boost off, robbing you of power.
The two images above show the real Achilles heel of the OEM intercooler and what is likely causing the heatsoak issues: the end tank design. There is a sharp angle that would be hard for the air to turn, meaning the bottom three internal runners shown with the red box are likely not actually doing much.