Background:
I came across this exchange in the comment section of a YouTube video on a Mk7 GTI intercooler installation.
The person commenting that the FMIC reduced airflow to the radiator was not swayed by my mention that the FMIC would block less of the radiator than a stock-location IC, which would “block” most of the radiator.
I inquired how they made their comparison, but they left the conversation.
This looked to me like one of several enthusiast claims I’ve come across where there is just enough logical plausibility to make a claim seem possible. But the actual process of collecting valid evidence and analyzing it is such a rarity among social media participants that the likelihood the claim was backed up with any degree of rigorous comparison was remote.
Fortunately, I had logged my car with a stock mount IC and then with the addition of a FMIC as part of a Bicooler effect test. I hadn’t intended to analyze oil temperature as a dependent variable for the IC configuration, but I had logged it at the time, so I could go back and analyze the data without conducting a dedicated test.
Test Setup:
The test that generated the data for this evaluation looked at Intake Air Temperature during a full-throttle pull, so the evaluation window needed to be expanded to cover the duration of the data collection session. Since recording oil temperature had not been the intention of the test, some of the data was logged from a cold start, and other data was logged from a warm start. Therefore, the cold ctart comparison has fewer data points.
The coolant temperature was also logged; therefore, I’m adding it to the comparison to see if there is any sign of the coolant temperature changing due to the “blockage” that supposedly raises the oil temperature.
Analysis:
Coolant temperature from a cold start increases similarly for each configuration.
Oil temperature from a cold start increases similarly for each configuration.
The following histograms show the range of temperatures during the drive once the coolant and oil have warmed up.
The mean temperature difference in coolant temperature between the configurations is 0.6 degrees Celsius.
The mean temperature difference in oil temperature between the configurations is 0.5 degrees Celsius. This is significantly smaller than the 15-degree Fahrenheit difference stated by the YouTube commenter.
Conclusion:
Cold-start warmup rate and post-warmup steady-state temperature for both oil and coolant remain statistically indistinguishable between the Majesty Competition and Majesty Bicooler configurations.
There is no evidence that the presence of the FMIC causes an increase in the oil temperature.
The claim that an FMIC blocks airflow to the radiator under normal driving, causing oil temperature to increase by 15 degrees, is not supported by the data recorded during this test.