Treadstone TR8C Installation

do88 + TR8C Bicooler


I’ve been experimenting with a few different bicooler combinations to try and find a pairing that cools very well. This post details a test using the do88+TR8C bicooler.

Most recently I had used the Integrated Engineering V1 stock location intercooler with a Treadstone TR8C.

Treadstone TR8C Intercooler End tank
Treadstone TR8C Intercooler End tank

This time the TR8C is being paired with the do88 stock location intercooler.

do88 Intercooler for Mk7 GTI
do88 Intercooler for Mk7 GTI

The Majesty front intercooler is removed and replaced by the TR8C.

Treadstone TR8C Installation
Treadstone TR8C Installation

Test Procedure:

The IS38 equipped GTI is operated in third gear during full-throttle acceleration. Acceleration begins around 2000-2500 RPM and concludes shortly after 6300 RPM.

The Intake Air Temperature measurement at 6000 RPM is compared with the Ambient Air Temperature and the difference is calculated. The temperature delta is used for comparison with other intercooler arrangements.

Note: This test is useful for comparing performance under typical operating conditions for my GTI, these conditions may not be as relevant for other owners.

Test Results:

Summary results for the IE and do88 test cases are shown using the boxplot:

IE vs do88 Bicooler Experiment - 6k RPM IAT over Ambient
IE vs do88 Bicooler Experiment – 6k RPM IAT over Ambient

The do88 test case spans a range of 5 to 18 degrees, prompting the use of a t-Test to assess the likelihood that there is no statistically significant difference in the results.

IE vs do88 Bicooler Experiment - t-Test of Mean IAT Delta Difference
IE vs do88 Bicooler Experiment – t-Test of Mean IAT Delta Difference

The lower temperature delta measured with the do88 holds up to the t-Test.

Although the mean temperature difference between the products is valid, I suspected another factor may be contributing to the results, with one of the most obvious potential factors being the intake air temperature when the full-throttle pull begins.

To check if this was potentially a significant contributing factor the starting intake air temperature was plotted versus the temperature delta for several bicooler configurations.

Bicooler Comparison - Overall
Bicooler Comparison – Overall

There does appear to possibly be a correlation between starting IAT and the delta temperature.

To try and make the correlation clear the data is reduced to only include the two stock location intercoolers used in the recent tests :

Bicooler Comparison - Initial
Bicooler Comparison – Initial

Finally, the data is grouped into five (5) degree Fahrenheit bins:

Bicooler Temperature Bins
Bicooler Temperature Bins

The resulting chart shows that above 100 degrees Fahrenheit starting IAT there is a strong correlation between the starting IAT and the delta temperature for each bicooler configuration.

The difference between the do88 and IE V1-based bicoolers looks less significant after processing the data.


Temperature rise during a third gear pull using a do88 stock location intercooler with Treadstone TR8C front-mounted intercooler was measured and compared with other bicooler configurations.

Results with the do88+TR8C combination were similar to other configurations, including the IE V1+TR8C.