Precision Raceworks BMW G8X S58 & G2X B58 Stand Alone Auxiliary Fuel System

The Precision Raceworks BMW G8X S58 & G2X B58 Stand Alone Auxiliary Fuel System is the ultimate solution for enthusiasts and tuners seeking the most stable, high-performance low-pressure fueling setup available for modern BMW engines. Designed specifically for the BMW G8X M3/M4 and G2X M240i/M340i/M440i platforms, this advanced auxiliary system delivers rock-solid fuel pressure, seamless integration, and unparalleled reliability—making it the most complete and technically refined port injection fueling solution on the market.

Now featuring plug-and-play connectors and AN8 adapters for your fuel rail, installation is easier and cleaner than ever—no cutting or modification to your factory harness is required.

Revolutionary Stand-Alone Fueling Technology

Traditional low-pressure fuel upgrades increase the output of the factory pump, but this method introduces limitations due to BMW’s OEM PWM-controlled fuel pressure system. These systems reduce output when target fuel pressure is exceeded, causing instability and oscillations that can compromise fueling accuracy, especially under load or boost.

Precision Raceworks eliminates these issues by providing a fully independent, stand-alone low-pressure system dedicated to your port injection. This ensures consistent, scalable fuel pressure that directly tracks boost levels, removing fluctuations and fuel starvation common with modified setups.

The result? Unmatched stability, cleaner fuel delivery, easier tuning, and more power potential.

Key Features & Benefits

• Billet Aluminium Top Hat:
  CNC machined from high-grade aluminium with three high-flow fuel ports for optimal configuration flexibility.

• Dedicated Fuel Pumps for Port Injection:
  Isolated fueling system designed to support port injection without interference from factory fuel pressure regulators.

• Fully Adjustable Billet Fuel Pressure Regulator:
  Allows 1:1 boost reference scaling, ensuring consistent fuel pressure relative to manifold boost for precision tuning.

• USA-Made 10-Micron Microglass Fuel Filter:
  Designed specifically for E85 and ethanol-based fuels, providing clean, consistent flow.

• Smooth Bore PTFE Fuel Lines (AN6):
  High-flow, ethanol-compatible lines ensure maximum durability and minimal flow restriction.

• Plug-and-Play Installation:
  Now includes factory-style connectors both inside and outside the top hat—no cutting or splicing required.

• Optimal Pump Location:
  Strategically positioned to prevent fuel starvation under hard acceleration or cornering.

• Configurable Pump Activation Harness:
  Customisable control over auxiliary pump activation for flexible tuning and setup.

• Ethanol Compatible Components:
  Every part of the system, from seals to fittings, is 100% ethanol-safe.

• Easily Expandable & Upgradeable:
  Supports future performance increases with multi-pump configurations and scalable hardware.

Available Configurations

• AFS.425: Single Walbro 450 (F9000274) fuel pump – flows 425 LPH @ 3 bar

• AFS.460: Single Walbro 535 (F9000295) fuel pump – flows 460 LPH @ 3 bar

• AFS.640: Dual Walbro 450s (F9000274) – combined 640 LPH @ 3 bar

• AFS.745: One Walbro 450 (F9000274) + one Walbro 535 (F9000295) – combined 745 LPH @ 3 bar

• AFS.800: Dual Walbro 535s (F9000295) – combined 800 LPH @ 3 bar

(Note: Male AN8-ORB to Female AN6-ORB adapter may be required for compatibility with some aftermarket fuel rails – not included.)

Compatibility

• BMW G80 / G81 M3

• BMW G82 / G83 M4

• BMW G20 / G21 M340i

• BMW G22 / G23 / G26 M440i

• BMW G42 M240i

Compatible with both S58 and B58 engines.

Why Choose Precision Raceworks?

Precision Raceworks is renowned for its innovative approach to fueling solutions, and this system represents the pinnacle of plug-and-play engineering for modern BMW performance. By isolating port injection from factory controls, this auxiliary fuel system ensures consistent AFRs, stable fuel pressure, improved injector resolution, and easier calibration for tuners. It’s the perfect foundation for any high-power, ethanol-fueled, or hybrid port/direct injection build.

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It is the responsibility of the customer to check with all federal, state local and environmental laws before ordering and installing a product. R44 Performance Limited is not responsible for any fees, fines or costs that a customer may incur as a result of failing to check with federal, state, local or environmental laws before ordering and installing a product.

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We totally understand if you're not certain a part will be compatible with your car, so we highly recommend contacting us here with your query. Our friendly sales team will then be in touch to confirm if this part is the correct part you are looking for.

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All of our products come with a standard warranty of 1-3 years. This is dependant on the type of product however. For more details please see our warranty page here.