Occasionally I’ll use the stock GTI airbox with a stock air filter, and after having the same air filter for a few years I decided to purchase a new Mann air filter and flow test it against the used stock filter to see how the airflow rates compare.
Since I was comparing these two air filters I figured I would add in the aFe Power air filter and 034 Motorsports air filter that I also have on hand.
The aFe filter also has some miles on it since I use it when conducting street tests with the stock intake
The configuration of the stock airbox for this test includes the removal of the stock air duct, removal of the snow guard/baffle, changing out the stock accordion hose for a 034 Motorsport silicone intake hose, and the 034 Motorsport turbo inlet elbow.
After checking the flow bench calibration the intake is attached to the flow bench using an adapter that simulates the stock IHI IS20 and IS38 turbocharger compressor inlets.
Airflow is measured through the intake system at a depression of 28″ of H2O.
The different air filters are swapped into the airbox and the test is repeated.
Next, a different flow bench adapter is used that simulates the compressor inlet of a hybrid turbocharger. This results in a change to the inlet inside diameter increasing from 49 mm (stock) to 56 mm (hybrid).
A turbo inlet elbow with a stock inlet diameter but a larger outlet diameter compared to the 034 elbow is used.
The rest of the test setup remains the same.
Next is a test with the stock air duct attached to the airbox to see what effect it may have at the higher airflow rate using the hybrid adapter.
The aFe air filter is used in the stock airbox for this test with the stock air duct attached.
The panel air filter flow rates with the stock IHI turbocharger adapter without the air duct attached to the airbox are shown in the chart below:
Notable is that the used stock air filter flows the same as the new stock filter.
Also notable is that the used aFe filter flows slightly less than the stock air filters, which is a change from the last time that I compared these two about four years ago.
Next is the comparison of air filters while using the hybrid turbocharger adapter:
The relative performance ranking between the air filters is the same order when using the hybrid adapter as it is with the stock adapter.
Finally, the stock air duct is added to the airbox while using the hybrid turbo adapter and aFe air filter.
A decrease of 5 CFM is observed with the addition of the stock air duct.
Four panel style air filters for the Mk7 GTI stock air box were tested to measure airflow rates through the intake system.
A lightly used aFe filter flowed slightly less than a used stock filter and a new stock filter.
A new 034 Motorsport air filter measured the highest air flow rate for both configurations tested.
The addition of the stock air duct decreased the airflow by 5 CFM when tested using a hybrid-turbo adapter.