Background:
Often, when discussing different intercooler options, one of the attributes that comes up is the volume.
This property consists of the core dimensions; the length multiplied by the height multiplied by the depth gives the core volume.
Concerning the quantity of charge air contained within the intercooler at any moment, this volume representation is incorrect. The reason is that what has been calculated is an external volume, the dimensions of a box, but not all of the external volume contains charge air.
Some of the external volume is made up of the charge air rows, the cooling fins, and passageways for external air to pass through.
I decided to compare the external volume to a measured internal volume to see how closely they compare.
Comparison:
To determine the enclosed volume, I would fill an intercooler with water and measure the quantity of water that the core and end tanks could hold.
A Mk7 Golf R intercooler will be compared with an APR Mk7 intercooler.
The Mk7 Golf R IC has an external volume of approximately 540 cubic inches, while the APR IC has an external volume of approximately 878 cubic inches.
Measuring:
The measurement process is straightforward, lay the intercooler on the ground and fill it with water.
While filling the IC, it is tilted a few times to help trapped air escape.
Once the water level is at the edge of the inlet and outlet, a cap is placed on one end to prevent spilling while the water is poured out for measuring.
Next, the process is repeated with the APR IC.
The difference in volume between the Golf R and APR ICs is 1200 mL, approximately 73 cubic inches, as shown in the picture below in the measuring glass.
A stock-size panel air filter is shown next to the water container for perspective on the volume difference.
Method comparison:
The external volume comparison (878 vs. 540) produced a difference of 338 cubic inches, while the direct measurement approach produced a difference of 73 cubic inches.
The calculated value is approximately 360% larger than the measured volume difference.
Notably, the measured comparison includes the volume of the end tanks, where the calculated value does not. If the enclosed volume of the end tanks were subtracted, the difference between the calculated and measured volumes could become larger.
Conclusions:
The difference between a calculated external volume for Mk7 intercoolers was compared with measured enclosed volumes.
When comparing a Mk7 Golf R IC and an Mk7 APR IC, the calculation method estimated a 360% larger volume than the direct measurement.