The Forge Motorsport intercooler for the Mk7 GTI that Forge kindly loaned for testing is up for the bench cooling test.
The Forge intercooler is attached to the flow bench and hot air sources are attached to the inlet pipe. A cooling fan is positioned to blow air directly onto the core once two minutes of heating have passed. The output air temperature is recorded for three minutes total. The test is then repeated twice with a cooling period between each test run.
The output air temperature from the Forge intercooler is shown on the chart with the blue line. Also shown are measurements that were recorded from the stock GTI intercooler, the Unitronic intercooler, and the AMS Performance intercooler.
All three aftermarket intercoolers perform very similar for the first 35 seconds of the test. The Unitronic and Forge intercoolers follow similar trends with the Forge intercooler producing slightly cooler output temperatures from about 60 seconds through the end of the test.
The AMS IC cools similar to the Forge IC showing approximately a 1 degree advantage for about 10 seconds, then after the 90 second mark the Forge IC shows a clear advantage for the remainder of the test.
Combining the Forge bench cooling results with the previous flow test the location on the composite performance chart is shown below:
Note: The bench cooling test criteria of temperature rise at two minutes was selected based upon the difference in airflow and temperature between this bench test and the operating vehicle. On the car the quantity and temperature of air exiting the turbocharger will exceed the conditions of the bench test. For this reason the bench test measurement is made at two minutes, to allow time for the intercooler to heat up, something that would occur more rapidly on the car when under boost. It is likely that as more bench data is recorded and can be compared with vehicle data logs for different intercoolers that the time that the measurement should be taken, to better approximate on vehicle performance, will change.
The Forge intercooler is the best performing on the bench cooling test of the products tested thus far. Performance on the air flow test lagged the other intercoolers. My goal is to identify an intercooler that performs well at both maximizing cooling and minimizing pressure drop across the IC. The Unitronic continues to best meet the criteria I have set.
The criteria for comparison on the composite chart is airflow at 28″ of H2O and degrees of temperature increase in output air after two minutes with high temperature internal airflow and no external cooling airflow. Other criteria could have been selected and while probably would not alter the results of the airflow comparison, the cooling comparison would be different depending on the criteria chosen. For instance, had 60 seconds been selected as the time to record temperature rise then the AMS IC would have ranked higher in cooling performance than the Unitronic and Forge intercoolers.
Another consideration is that the tests are not being made under the same conditions that the vehicle operates. Use of these results to draw conclusions about on vehicle performance depends on the confidence each person gives to the test methods. With four product data points for the bench tests and one product data point on my GTI there isn’t sufficient information to determine how well the bench cooling test correlates with on vehicle cooling performance. As more bench data is recorded and additional on vehicle data logs are recorded a better picture will form for how the bench test correlates with vehicle data.