BMW G42 M240i 700+ HP Build: Parts, Process, and Dyno Results
How much power can a BMW G42 M240i make on its stock motor? In this build, Kevin’s B58-powered M240i went from a three-run baseline average of approximately 379 wheel horsepower to a video-reported 741 wheel horsepower.
Getting there required much more than increasing boost. The car received an unlocked DME, upgraded turbo and airflow components, additional fueling, improved charge cooling, supporting ignition and crankcase modifications, and custom tuning. Before installing the major hardware, the Kies team also tested an off-the-shelf 93-octane tune and an E40 blend to show how the setup responded at several stages.
From 379 to 741 wheel horsepower
Open the full build video on YouTube →Starting Point: The M240i Baseline
Kevin’s M240i began the video on its stock engine calibration, but it was not completely stock: it already had an intake, downpipe, and full exhaust. Three back-to-back baseline pulls averaged approximately:
- 379 wheel horsepower
- 390 lb-ft of wheel torque
With that starting point established, the team tested the tuning and fuel options before installing the larger hardware package.
Step-by-Step BMW G42 M240i Build Summary
1. Unlock the DME
The DME had to be unlocked before compatible tuning software could flash the required calibrations. Kevin’s DME was unlocked at Kies Motorsports before filming.
DME eligibility can vary by production date, hardware, software version, and previous programming history. Confirm compatibility before ordering or removing a module.
2. Flash the MHD Stage 2 93-Octane Map
With the DME unlocked, the team used the MHD Super License for F- and G-Series B58 and flashed an off-the-shelf Stage 2 map for 93-octane fuel.
The Stage 2 testing averaged approximately 435 wheel horsepower and 501 lb-ft of wheel torque—reported gains of roughly 58 horsepower and 109 lb-ft over the initial averages.
3. Add Flex-Fuel Monitoring and Test E40
Next, the team installed the MHD CAN FlexFuel Analyzer QuickInstall Kit. With the system configured in MHD, the car was tested at approximately E40.
That increased the average to approximately 485 wheel horsepower and 571 lb-ft of wheel torque. Ethanol content must be measured rather than assumed, and the calibration must match the actual fuel blend and hardware.
4. Replace the Factory Turbo With a PURE900
The factory turbo was no longer appropriate for the build’s 700-horsepower objective, so it was replaced with the BMW G-Series B58 PURE900 Turbo.
During installation, the center section received Liqui Moly Pro-Line Turbocharger Additive for startup lubrication, as demonstrated in the video. Always follow the turbo manufacturer’s current installation and priming instructions.
5. Upgrade the Intake and Turbo Inlet
The build used the MST BMW B58 Cold Air Intake and Inlet System, which the video identifies as the configuration designed for the PURE900 application.
6. Increase Low-Pressure Fuel Supply
The build added the Visconti G42 M240i Stage 1 Fuel System Upgrade. In the video, the setup uses a Walbro 525 pump in conjunction with the stock low-pressure pump and supplies both the factory direct-injection system and the added port-injection system.
7. Install the Do88 Charge Cooler Manifold
The factory charge-cooling assembly was replaced with the Do88 B58 Charge Cooler Manifold.
For this build, the unit provided upgraded charge cooling plus injector provisions and a fuel rail for supplemental port injection. The video describes it as an all-aluminum assembly with an approximately four-inch Garrett core and 11 cooling rows, compared with six rows in the removed factory unit.
8. Add Six FIC Port Injectors
The team added six FIC 1000cc Injectors to the Do88 manifold’s port-injection rail. These supplement the factory direct-injection system for the upgraded turbo and ethanol blend used in the final calibration.
9. Control Port Injection With MOTIV ReFlex
The MOTIV ReFlex Port Injection Kit managed the six supplemental injectors and integrated with the MHD-based calibration strategy.
10. Upgrade the Spark Plugs
The factory plugs were replaced with the NGK B58 Spark Plug Bundle. The video identifies them as NGK 96206 iridium plugs and shows them being gapped to 0.022 inch for this specific setup. Plug selection and gap should follow the tuner’s direction.
11. Refresh the Oil and Coolant
Because turbo replacement can result in some fluid loss, the oil and coolant were refreshed before the next dyno session. The video features:
- Liqui Moly Special Tec B FE 5W-30 Oil Change Kit
- Liqui Moly MoS2 Anti-Friction Engine Treatment
- BMW Genuine OEM coolant
The oil choice was specific to this build. Verify the required specification and viscosity for the vehicle, climate, use, and tuner or engine-builder recommendation.
12. Address Crankcase Ventilation
Before tuning, the team installed BMR B58 PCV Block-Off Pins and a BMR Gen 2 B58 Catch Can Kit. The video recommends reviewing the PCV modification when operating above 30 psi; the correct setup should be confirmed with the vehicle’s tuner.
13. Develop the Custom MOTIV Calibration
Chris from MOTIV calibrated the completed hardware combination with the MOTIV ProTUNING B58 Tune.
The process progressed from a new 93-octane baseline to several 93-octane revisions, then to measured ethanol fuel. The revised 93-octane map produced 519 wheel horsepower and 520 lb-ft of wheel torque before the E74 calibration.
14. Record the Final E74 Result
With the PURE900, upgraded intake and inlet, charge cooling, low-pressure fuel upgrade, port injection, ReFlex controller, supporting modifications, and custom tune, the M240i recorded:
- 741 wheel horsepower
- 668 lb-ft of wheel torque
The video reports gains of 363 horsepower and 277 lb-ft over the rounded baseline figures used in its final comparison. This was a stock-motor result, but it was not an otherwise stock vehicle.
Dyno Results
| Configuration | Fuel | Wheel horsepower | Wheel torque |
|---|---|---|---|
| Initial baseline: stock calibration with existing intake, downpipe, and exhaust | 93 octane | Approx. 379 hp average | Approx. 390 lb-ft average |
| MHD off-the-shelf Stage 2 map | 93 octane | Approx. 435 hp average | Approx. 501 lb-ft average |
| MHD off-the-shelf ethanol calibration | E40 | Approx. 485 hp average | Approx. 571 lb-ft average |
| Upgraded hardware, initial custom-tune baseline | 93 octane | 476 hp | 490 lb-ft |
| Upgraded hardware, revised MOTIV calibration | 93 octane | 519 hp | 520 lb-ft |
| Upgraded hardware, final MOTIV calibration | Measured E74 | 741 hp | 668 lb-ft |
The video uses slightly different rounded baseline references at different points: approximately 379/390 for the initial three-run averages and 378/391–392 in later graph comparisons.
Complete Featured Build List
- Kies Motorsports USA DME Unlock Service
- MHD Super License for F- and G-Series B58
- MHD CAN FlexFuel Analyzer QuickInstall Kit
- BMW G-Series B58 PURE900 Turbo
- MST BMW B58 Cold Air Intake and Inlet System
- Do88 B58 Charge Cooler Manifold
- MOTIV ReFlex Port Injection Kit
- Visconti G42 M240i Stage 1 Fuel System Upgrade
- FIC 1000cc Injectors
- Liqui Moly Special Tec B FE 5W-30 Oil Change Kit
- Liqui Moly MoS2 Anti-Friction Engine Treatment
- Liqui Moly Pro-Line Turbocharger Additive
- NGK B58 Spark Plug Bundle
- BMR Gen 2 B58 Catch Can Kit
- BMR B58 PCV Block-Off Pins
- MOTIV ProTUNING B58 Tune
- BMW M240i G42 Valvetronic Valved Sport Exhaust System
Key Takeaways
- The car began with a stock calibration but already had an intake, downpipe, and exhaust.
- The 93-octane MHD Stage 2 test averaged approximately 435 wheel horsepower.
- E40 and flex-fuel monitoring increased the average to approximately 485 wheel horsepower.
- The final result required a larger turbo, more low-pressure fuel supply, six port injectors, a controller, improved charge cooling, supporting ignition and crankcase changes, and custom tuning.
- The final 741-wheel-horsepower result used a measured E74 blend and applies only to this car, hardware combination, fuel, calibration, dyno, and test conditions.
Safety, Fitment, Emissions, and Warranty Disclaimer
This article summarizes one modified vehicle; it is not a universal installation or tuning manual. Turbocharger work, fuel-system changes, ethanol fuels, electrical wiring, DME programming, and dyno testing can cause fuel leaks, fire, drivetrain damage, personal injury, or property damage if completed incorrectly. Installation and calibration should be completed or supervised by qualified professionals.
Confirm every component using the vehicle’s VIN, chassis, engine, production date, DME version, drivetrain, existing modifications, and current product-page information. Hardware and software compatibility can change.
Downpipes, exhaust components, calibrations, fuel-system changes, and other emissions-related modifications may not be legal for public-road use. Follow all applicable laws. Modifying or tuning a vehicle may also affect warranty coverage. No power level, reliability outcome, or engine life is guaranteed.