BMW 135i Stage 2 Tune (2013) – 380 HP & 520 Nm | N55 Performance Upgrade

The BMW 135i (2013) equipped with the N55 engine is one of the best platforms for Stage 2 tuning.

With the right hardware and a properly developed calibration, this setup delivers 380 HP and 520 Nm while maintaining OEM-level smoothness and reliability.

This Stage 2 tune focuses on usable torque, clean combustion, and long-term engine safety rather than chasing peak dyno numbers.

Why Stage 2 on the BMW 135i N55?

The N55 responds exceptionally well to increased airflow and optimized boost control.

Stage 2 allows the turbocharger to operate more efficiently, unlocking strong mid-range torque and a much sharper throttle response.

Key benefits include:

- Strong pull from low RPM

- Linear power delivery

- Improved top-end performance

- Safe ignition and AFR control

Required Hardware for BMW 135i Stage 2

To safely achieve 380 HP, the following hardware is recommended:

- High-flow downpipe

- Upgraded chargepipe (OEM units are known to fail under higher boost)

- Fresh spark plugs, correctly gapped for tuned boost levels

- Optional front-mount intercooler to stabilize intake air temperatures

BMW N55 Stage 2 Calibration Details

Boost Control:

Higher sustained boost in the mid-range.

Faster spool-up.

Smooth boost taper to keep exhaust gas temperatures under control.

Fueling and AFR:

Clean and stable wide-open throttle AFR.

Corrected load and torque targets.

Stable fuel trims under all operating conditions.

Ignition Timing:

Knock-safe ignition maps.

Zero timing pull across the full dyno sweep.

Crisp and immediate throttle response.

Torque and Daily Driveability

Despite the significant power increase, the car remains easy to drive on a daily basis.

Strong mid-range torque without surge.

Linear and predictable acceleration.

Improved gearbox behavior in both D and S driving modes.

Performance Results – BMW 135i Stage 2

Power output: 380 HP

Maximum torque: 520 Nm

The result is a noticeably more aggressive driving character while retaining factory-like refinement and reliability.

Dyno and Log Validation

All critical parameters were validated under real driving load:

- Air-fuel ratio

- Ignition timing

- Wastegate duty cycle

- Intake air temperature

This ensures:

- No knock

- No boost overshoot

- No fuel cut

- Stable AFR across the entire pull

ACE Tuning File Service