Table of Contents
Background:
The G-Plus intercooler is a small front-mounted intercooler (FMIC) that has silicone connector hoses with a branch that connects with the Mk7 GTI stock location intercooler to form a bicooler.
Of the bicooler setups that I have tried the G-Plus is the first that I have encountered that uses a Tube and Fin style core.
Previously the G-Plus with Stock GTI IC was flow tested, and not surprisingly the pair of intercoolers flows very well.
In this post measurements of temperature and pressure recorded while operating on the street will be reviewed.
Test Procedure:
The GTI is operating primarily with a Shuenk IS38+ turbocharger and a custom E30 tune from Stratified with a boost curve shown on the chart below. The operating range of interest begins at around 2,000 RPM and concludes at around 6,300 RPM. The vehicle’s starting speed for the timed interval is 47 mph and the ending speed is 84 mph.
Full throttle acceleration will be repeated several times.
The difference between the intake air temperature and the outside air temperature will be calculated at an engine speed of 6,000 RPM.
For a comparison of boost onset, a Mabotech M520 turbocharger is utilized. The rate of boost building when using the stock IC alone and then when the G-Plus and Stock IC are used together will be compared.
G-Plus Test Results:
A series of fifteen (15) full-throttle pulls are made. An overview of the data collection session is shown below.
- T_Out is the temperature exiting the turbocharger
- OAT is the outside air temperature
- IAT is the intake air temperature inside the intake manifold
The trend of the IAT above OAT during the session is shown below:
Summarizing this temperature data into a boxplot is shown next:
The pressure drop between the turbocharger outlet and intake manifold is shown in the next boxplot:
The next chart compares the G-Plus bicooler configuration with the stock GTI IC alone, and also with the G-Plus paired with an AMS stock location intercooler.
The next charts show the time for the boost to build when using the stock IC and then the stock IC with G-Plus as a bicooler.
This shows the boost onset data in a more common format.
The dashed lines are of the stock GTI IC and the solid lines are the G-Plus/Stock IC.
Conclusions:
The Stock GTI IC along with the G-Plus FMIC was installed on a Mk7 GTI to record temperature and pressure data during a series of full-throttle pulls.
Fifteen pulls were recorded and the average intake air temperature over ambient was approximately 20 degrees Fahrenheit at 6,000 RPM. This difference varied with the amount of recovery time in between pulls and the time during the data collection.
The peak pressure drop during the pulls averaged approximately 1.9 psi.
In comparison with the stock GTI IC alone, the addition of the G-Plus lowered the IAT on average by 11 degrees Fahrenheit, which approaches 15-20 degrees cooler toward the later part of the collection session.
Replacing the stock GTI IC with an AMS stock location IC and pairing that with the G-Plus led to an average 10 degF further reduction in the temperature, although making a pull-to-pull comparison, the temperature difference was around 7 degF for individual pulls.
Comparing trend lines of boost onset data shows a maximum difference in boost onset time of 0.1 seconds. (This is likely less than the margin of error for this measurement as it was shown during the duct testing that the pre-turbocharger intake air temperature can affect boost onset more than this amount, and the pre-turbo air temperature was not recorded.)
Overall the G-Plus addition to the stock Mk7 GTI IC led to a 33% (33 to 22 degF) reduction of the intake air temperature above the ambient temperature and a reduction of pressure drop by 42% (3.3 to 1.9 psi). No adverse effects were observed on the boost onset time.