An aftermarket turbo inlet elbow is a part I’ve used for a while due to the increase in airflow the aftermarket versions provide compared to the stock GTI part.
A benefit frequently attributed to using an elbow is quicker turbocharger spool up. Although I have seen this benefit mentioned, I have not seen it quantified.
I decided to conduct a test to see what difference there is between an aftermarket turbo inlet pipe (TIP) and the stock GTI inlet pipe.
For this test, I am comparing the stock GTI TIP and the 034 Motorsport TIP.
The starting condition is in third gear and engine operating speed between 1500-3000 rpm. At the start the accelerator is depressed enough to maintain steady-state speed and then it is fully depressed.
After the boost pressure rises past 20 psi the accelerator is let off and the GTI is slowed. This process is then repeated several times.
39 data points were recorded using the stock inlet elbow and 47 data points were recorded using the 034 inlet elbow.
The time for the boost pressure to increase from 1 psi to 20 psi is recorded and plotted against the engine speed when 1 psi was reached. This post addresses why this method of comparison is used.
Data for each turbo inlet elbow is shown in the chart:
The 034 Motorsport turbo inlet elbow promotes slightly faster boost onset times when compared with a stock GTI turbo inlet elbow.
Trend lines show that the test case with the 034 elbow is reaching 20 psi slightly less than 1/10th of a second faster than when using the stock GTI elbow.
The variation among data points is greater than the difference between the data trend lines, suggesting that the difference in performance would not be noticeable to a driver.