This is a FrankenTurbo F21 turbocharger turbine housing for the Audi 1.8T engine minus the turbine wheel.
![FrankenTurbo F21 1.8T turbine housing on flowbench](https://myaudis4.com/wp-content/uploads/f21_1pt8_turbine.jpg)
Below are the airflow test results compared against BorgWarner B5 S4/RS4 K03 and K04 turbochargers with turbine wheel installed.
![F21 1.8T Airflow Test Results](https://myaudis4.com/wp-content/uploads/f21_1pt8_turbine_housing.png)
This is a FrankenTurbo F21 turbocharger turbine housing for the Audi 1.8T engine minus the turbine wheel.
Below are the airflow test results compared against BorgWarner B5 S4/RS4 K03 and K04 turbochargers with turbine wheel installed.