Spool BMW B58 Gen 2 Auxiliary Split Fuel System
Spool BMW B58 Gen 2 Auxiliary Split Fuel System
Spool BMW B58 Gen 2 Auxiliary Split Fuel System separates the direct-injection and port-injection fuel feeds for more stable, boost-referenced fueling on higher-output BMW B58 builds.
- Dual Walbro 450 pumps supplied as the base configuration
- Optional dual Walbro 525 configuration for higher fuel demand
- OEM fuel-pump top-hat integration using precision-machined fittings
- Plug-and-play ReFlex controller compatibility
- Triple-layer PTFE fuel plumbing with stainless reinforcement
- Compact boost-referenced Spool fuel-pressure regulator
Fitment: BMW B58 Gen 2 applications listed by Spool: M340i/M340i xDrive 2020+, M440i/M440i xDrive 2021+, X3 M40i 2020+ and X4 M40i 2020+.
Important: Spool's solid-state PWM relay harness is a separate option. Confirm pump choice, port-injection controller, injector size and base pressure with the tuner.
Dispatch: Special order — allow 3–4 weeks.
Supplier
Spool Performance
Product System
- Fuel System
Vehicle Fitment
- BMW 340I M340I G20 G21 B58
- BMW 4 Series G22 B58
- BMW 4 Series G23 B58
- BMW 4 Series Gran Coupe G26 B58
- BMW X3 G01 B58
- BMW X4 G02 B58
Confirm chassis, engine, drivetrain and production-year compatibility before ordering.
Available Options
Pump
- Walbro 450 with check valves
- Walbro 525 with check valves
Supplier Part Numbers
SP-B58G2AUXF450, SP-B58G2AUXF525
Built by Boost & Tune Support
BBT can assist with fitment review, installation, supporting modifications, configuration and calibration requirements where applicable.