BMW M140i / M240i (F20,F21,F22)

Tuning guide

The 40i BMW engine range are equipped with the B58 engine, a 3.0 single turbo (Twin Scroll) straight 6, equipped with dual Vanos, Valvetronic (Variable cam lift) direct injection engine.
Which quite frankly is a little gem, producing full torque under 2000rpm yet still able to peak power at the top end of the rev range. Usually paired with the equally as impressive ZF8 automatic gearbox which makes gearchanges effortless, removing all negativity we usually expect with automatic gearboxes.

Released with official figures of 340hp by the manufacture, this is rarely the case on the dyno - with most companies including ourselves regularly seeing 360-370hp prior to tuning.

The straight 6 engine is part of BMW's modular engine family (B38/B48). The B58 which you will find installed on most the current models (3 Series, X3, X5 etc) this post is relevant to most models equipped with this engine also.

With no real common weak links yet apparent, the main limitation will come from inlet temperatures as the charge cooler is built into the inlet manifold as a one piece unit. Currently there are only upgrades for the charge cooler radiator to improve cooling.

B58 Engine ECU tuning can be offered across two options, our standard CustomPro tune with its proven calibrations, alternatively we can offer  BM3 (Bootmod3) software for the end users who like to fine tune some settings themselves. TCU (Transmission) tuning can also be offered on the ZF8 Automatic gearboxes by XHP, for the perfect combination.

For the power hungry folks, or those who simply want to improve their soundtrack - plenty of upgrades can be offered from MOT legal exhaust systems, full track system (Not road legal) can be offered, along with Hybrid turbo chargers and engine cooling upgrades.

For those Track Addicts, Nurburgring goers or simply for those who have increased their power and need to match chassis we can offer simple upgrades from lowering springs, performance pads to full coilover systems. anti roll bars and limited slip differential upgrades.

Stage 1

The first step with extracting power from the B58 engine requires no hardware changes, this is software only upgrade. The ECU software follows the linear torque delivery  like stock through the low to mid range while adding a flat 50lbf still, in the higher rpm at the point the standard power curve starts to flatten off we keep the power climbing, peaking and holding the power to the limiter where as much as 430HP can be seen.

We retain this flat torque delivery for driveability reasons, most of the 40i models do not come equipped with an LSD, with this in mind additional torque / spikey delivery can provoke unwanted wheel spin, and show up chassis limitations.
On request additional torque can be offered on request (Limited slip differential advised) with a TCU tune.

With our 'Stage' software upgrades the following features are included:

  • Vmax Removal (Speed limiter removed)
  • Sports Displays recalibrated to suit new outputs
  • Enhanced over run (Optional)
  • Switchable map modes (Certain Software versions only)

Expected Results, based on our Dyno Dynamics rolling Road:

+70-90HP (410-430HP)

+ 50-60LBFT (450-460LBFT)



Stage 2

The final step with maximizing the efficiency of the stock turbochargers is removing the catalyst in the downpipes, Removal of the standard catalyst upgrade is recommended to install a sports cat to retain MOT legal status, or decatted for optimal gains (Track use only) . With the free flowing downpipe installed fueling can be optimized and new lambda targets set, and slight increase of boost and ignition timing taking into account the less restrictive exhaust system.
Standard cat back can be still retained, how ever optimal results are based on free flowing turbo back system.
Low end response is improved and turbo lag is reduced, torque levels will be held similar to stage 1, but power in higher RPM will increase by 10-20hp.

This stage 2 includes option for, GPF delete, cold start delete (Removal of high / loud idle) along with Catalyst code removal to avoid EML lights.

Expected Results, based on our Dyno Dynamics rolling Road:

+100-120HP (440-460HP)

+ 50-60LBFT (450-460LBFT)

Stage 3

The stock turbochargers are the limiting factors when it comes to the next stage of performance, with compressor / turbines limiting any more flow. With larger compressor and turbines installed into the stock turbo housings, these 'Hybrids' allow much great flow of air flow, and exhaust gas flow. High flow downpipes are must at this state of tune, and with a cat back system advised for optimal gains.
Charge temperatures start to creep up, when increasing the boost pressures - so depending on target HP and usage we would advise a charge cooler radiator upgrade as well.
Water Methanol would also be a upgrade when pushing to the upper figures. Wide range of power is given at this stage due to several factors.

TCU Flash is highly recommended at this level of tune.

Expected Results, based on our Dyno Dynamics rolling Road:

+160-260HP (500-600HP)

+ 60-100LBFT (460-500LBFT)


Dyno Testing

All ECU remaps are carried out on our State of the Art Dyno Dynamics Dynotech rolling road, which can read upto 1200HP

Data Logging

Each car is hooked up to a Wide band lambda sensor to ensure correct air to fuel ratio, along with data logging tools to ensure Boost, Ignition timing parameters are all incheck

Diagnostic Check

We carry out a pre and post tuning ECU diagnostic trouble code check (DTC) to ensure no faults are present before or after tuning