A K03 is not a single, fixed-size turbocharger but rather a series of turbochargers, primarily manufactured by BorgWarner (formerly KKK) and commonly found in various Volkswagen Audi Group (VAG) vehicles. While sharing the "K03" designation, different variants within this series feature distinct compressor and turbine dimensions, optimized for specific engine power outputs and characteristics.
Understanding K03 Turbocharger Sizes
The size of a K03 turbocharger is defined by its compressor and turbine wheel dimensions, typically measured in millimeters (mm). These measurements reflect the inducer (smaller diameter where air enters) and exducer (larger diameter where air exits) sizes of the wheels. Variations in these dimensions contribute to different airflow capabilities and power potential for each K03 variant.
Here's a breakdown of common K03 turbocharger sizes and their associated engines:
| K03 Variant | Compressor Size (Inducer/Exducer) | Turbine Size (Inducer/Exducer) | Common Engines Using This Turbo |
|---|---|---|---|
| K03-005 | 36mm / 50mm | 36mm / 45mm | Primarily used in earlier 150ps 1.8T engines such as AEB, APU, ATW, ANB, and the 180ps AJL. |
| K03-029 | 36mm / 50mm | 40mm / 45mm | Found in 150ps AVJ, AWT engines, 163ps BFB, 170ps AMB, AWM, and 180ps AWP 1.8T engines. This variant often features a slightly larger turbine for improved flow. |
| K03-073 | 38mm / 51mm | 40mm / 45mm | Typically equipped in higher output 190ps 1.8T engines like the BEX and BVR, featuring a larger compressor wheel for increased airflow. |
Key Takeaways
- Compressor Size: Dictates how much air the turbo can efficiently compress and deliver to the engine. A larger compressor can support higher horsepower.
- Turbine Size: Influences the turbo's responsiveness (spool time) and its ability to expel exhaust gases efficiently. A larger turbine can reduce back pressure at higher RPMs, but might increase lag.
- Engine Application: Different K03 variants were designed to match the specific power and performance requirements of various 1.8T engines across the VAG lineup.
While the K03 series is generally considered a relatively small turbocharger, suitable for mild power gains and excellent daily drivability, the specific dimensions vary significantly enough between models to impact their peak performance characteristics.
