Table of Contents
Background:
A little over two years ago, I installed a stock Golf R IC in my GTI to compare its performance to the GTI IC. The results showed that the GTI IC was cooling slightly better (~3 degF) than the Golf R.
As I noted at the time, the relatively few pulls made with the GTI IC were a concern that could have significantly affected the results.
Note: This dependence on the number of pulls made and the grouping of the pulls contributed to my decision to move away from using the chart format shown above and rely more upon the intake air temperature (IAT) trends during pulls. This method of data display is shown below.
Since recording the first data with the GTI IC, I have reinstalled the stock intercooler and made a series of pulls on several occasions that more closely match the Golf R IC data collection. This post compares the aggregated data from GTI IC with the Golf R IC.
Test Process:
Data is logged during a series of full-throttle third gear pulls. The engine speed at the start of the pull is around 2,000 RPM, it is around 6,500 at the conclusion.
An overview of the data collection method is shown below.
Note: The stock GTI IC is paired with an IS20 turbocharger using a Stage 2 tune, where the Golf R data was collected using a Shuenk IS38+ turbocharger.
Interestingly, the turbocharger outlet air temperature for both setups shows that the air temperature is similar for the IS20 and IS38 at the operating boost pressure of the respective tunes, approximately 375-380 degF.
After recording the intake air temperatures, the data is combined with previously recorded data from the GTI IC and compared with the Golf R data. The metric of interest is the intake air temperature above the ambient air temperature at an engine speed of 6,000 RPM.
Test Results:
The first chart shows the intake air temperature change from the stock GTI IC as the series of pulls progresses.
The following chart compares the data points from each intercooler, represented by the circles and the mean, expressed with the square.
The following box plot shows the same data points in a different format.
Then, looking at the temperature differences in histogram format.
The GTI appears to have a slight advantage over the R IC. However, the data collection with the GTI IC did not match the number of pulls made with the Golf R IC – 17 consecutive pulls during one session.
To account for the variance of the data sets, a t-Test is made with the hypothesis that the mean temperature rise is the same for both intercoolers.
At a 0.05% significance level, there is no statistically significant difference between the mean temperature rise for the two intercoolers.
Conclusions:
The Golf R IC and GTI IC were compared using data recorded on the street.
The intake air temperature from each intercooler was recorded and analyzed. The results show no statistically significant difference in the rise in intake air temperature when operated under the conditions described in this post.
Another attribute of interest is the pressure drop created by each intercooler. The slightly thicker Golf R IC has an advantage in this measure. At a pressure drop of 28″ of H2O, the Golf R IC flows approximately 39 CFM more (~19%) than the GTI IC.