Table of Contents
Background:
Prior testing of some duct configurations to determine their effect on the turbocharger inlet air temperature evolved into testing a pair of popular open-style intakes.
In this post, I discuss using an Eventuri closed intake with an MST silicone inlet hose and recording pre-turbocharger air temperature during full-throttle acceleration to compare with the other tested configurations.
Although the GTI is equipped with an intercooler, the air temperature entering the turbocharger is important to the power required by the compressor to increase the pressure of the air. Warmer air is less dense and this raises the power requirement for compression.
Test Procedure:
The Eventuri intake with a silicone MST turbo inlet hose is installed in my GTI. The car is driven for several minutes to bring the engine oil up to normal operating temperature and then a series of third-gear full-throttle pulls are made to record the pre-turbo air temperature at an increased airflow rate.
During this session, a total of three (3) full-throttle pulls are made to support averaging the air temperature data.
Test Results:
An overview of the data collection session including the turbocharger inlet air temperature (TIT) is shown below.
A close-up of the data during the third gear pulls is shown next.
Configurations being compared in the remaining charts are:
| Duct Configuration Label | Duct Configuration |
|---|---|
| D1 | CTS Intake / Stock Air Duct |
| D2 | CTS Intake / Stock Duct w/ Open Driver’s Side |
| D3 | CTS Intake / Stock Duct w/ Open Drv. Side and Covered Rear Pax Side |
| D4 | CTS Intake w/ Foam Around Heat Shield / D3 Configured Air Duct |
| D5 | CTS Intake Without Heat Shield / D3 Configured Air Duct |
| IE V2 (D6) | IE v2 Intake / IE v2 Air Duct |
| APR PEX (D7) | APR PEX / D3 Configured Air Duct |
| Eventuri (D8) | Eventuri Intake / MST Hose |
The first chart shows the Turbo inlet air temperature versus the outside air temperature at the start of the pull.
The gray circles are the individual data points. The square symbol is the mean temperature difference value. All temperature measurements are in degrees Fahrenheit.
The next chart shows the pre-turbo air temperature rise, or fall (if below zero), during the pulls:
The final chart shows how high the pre-turbo air temperature is above the outside air temperature at the end of the pull.
Conclusions:
The pre-turbocharger intake air temperatures were measured with the GTI equipped with an Eventuri intake and MST silicone turbo inlet hose. Temperatures during full-throttle pulls were compared with several other configurations that have been tested.
The starting temperature difference is similar to other intakes, although slightly higher than the IE V2 and APR PEX open intakes. It’s possible that the small number of data points (3) factored into producing this unexpected result.
The decrease in pre-turbo air temperature during the pull is greatest with the Eventuri intake. This can partially be explained by the slightly higher-than-expected starting temperature, but not completely. It is evident that the closed intake design also contributes to the large temperature drop.
The final temperature above ambient is tied with the APR PEX for the lowest recorded thus far.