Turbo Tech: Intercooler Testing (with a dash of thermo and a pinch of heat transfer)
by Khiem Dinh
Khiem Dinh is an engineer for Honeywell Turbo Technologies at the time of this writing. All statements and opinions expressed by Khiem Dinh are solely those of Khiem Dinh and not reflective of Honeywell Turbo Technologies.
An intercooler is essential for maximum performance on a highly boosted turbocharged vehicle (no duh right?). However, just putting an intercooler into the system does not guarantee it will cool down the charge air (air compressed by the turbocharger) efficiently. A number of variables contribute to the efficiency of an intercooler: size, design, end tank design, and volume of cooling air moving through the intercooler to name the big variables. You can try to calculate efficiency, or you can just measure it. Ain’t nothing better than the real thing, so I opted to measure it using a portable thermocouple data logger.
This is the Greddy intercooler on Project Evo X GSR. The design of the end tanks along with their internal features affects the efficiency of the intercooler. The Greddy IC has internal air diverters in the end tanks to better distribute the airflow through the core to improve cooling. In other words, good luck trying to guess the efficiency of an intercooler just by looking at the outside of it.
In order to calculate the basic intercooler efficiency value, we needed to measure three temperatures: the temperature of the charge air going into and out of the intercooler, and the temperature of the ambient air flowing externally through the intercooler.
This is the portable data logger I picked up which can record up to four temperatures at once.
A basic intercooler efficiency calculation is the change in the charge air temperature going through the intercooler divided by the difference in the temperature of the hot charge air and ambient air temperature: efficiency = (‘charge air into IC’ – ‘charge air out IC’)/(‘charge air into IC’ – ‘ambient air’). If the intercooler does no cooling at all, then you end up with zero efficiency. If the charge air is cooled down to ambient, the intercooler would be 100% efficient (which is impossible).