Bicooler with Air Conditioning On


This post discusses evaluating temperature from the bicooler with air conditioning on.

Several weeks ago a comparison was made of a front-mounted intercooler and stock location intercooler when the GTI air conditioning system is running. The intercooler outlet air temperature in the cold side charge pipe was compared between the two during a ~30-minute drive that simulated stop-and-go driving.

This comparison raised a question about how a bicooler with air conditioning on would perform under similar operating conditions. This post discusses the investigation that was conducted and the outcome.

eBay Bi-cooler Intercooler Install
Majesty Bi-cooler Install

Test Procedure:

The GTI is equipped with a Majesty front-mounted intercooler and a do88 stock location intercooler with the two connected in a bicooler configuration.

The remainder of the setup, route and operating speeds are the same as was described in the prior test.

Test Results:

The intercooler outlet temperate, intake air temperature, and operating speed are shown for the drive in the chart below.

Bicooler AC On Temperatures
Bicooler AC On Temperatures

The next chart shows a histogram of the IC outlet temperature over ambient during this drive. The bins are the temperature delta in degrees F.

Bicooler AC On Histogram
Bicooler AC On Histogram

The next three charts compare all three intercooler configurations; FMIC only, SMIC only, and Bicooler.

This chart shows the IC Outlet air temperature over ambient over the drive route.

Bicooler AC On vs SMIC & FMIC
Bicooler AC On vs SMIC & FMIC

The IC Outlet temperature over ambient data is summarized with a bar chart showing the percent of data points in each of the 5 degrees Fahrenheit bins:

Bicooler AC On Summary Histogram
Bicooler AC On Summary Histogram

The data points are further combined into box plots:

Bicooler AC On vs SMIC vs FMIC Boxplot
Bicooler AC On vs SMIC vs FMIC Boxplot

This chart shows the bicooler temperature delta minus the FMIC temperature delta throughout the drive:

Bicooler AC On vs FMIC
Bicooler AC On vs FMIC


The addition of the FMIC to the stock location intercooler results in a slight increase to the outlet air temperature as compared to the stock location intercooler alone. The average difference over this test route is 3 degF.

The difference between the average temperature from the FMIC to the Bicooler is 13 degF.

As the last chart illustrates, the Bicooler minus FMIC temperature difference varies by approximately 5 to 15 degF after the mid-point of the drive. This is where the peak speeds increase to around 45 mph, as shown in the first chart.

Overall the results with the air conditioner operating are not surprising. The stand-alone FMIC has the lowest average outlet temperature. The stock location intercooler has slightly higher outlet temperatures, and the FMIC along with the stock location IC has the highest outlet temperature.

3 thoughts on “Bicooler with Air Conditioning On”

  1. Thanks Jeff. Great stuff and good guidance.for those of us with FMIC who might consider bicooler.

  2. Im so glad you fully rounded out this test. Great data. Pretty much what I suspected.

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