Spool FX-350 Upgraded High Pressure Fuel Pump Gen 2 B58: The Ultimate Power Upgrade for Your BMW

If you own a 2020+ BMW with a Gen 2 B58 engine and are chasing serious horsepower, the Spool FX-350 upgraded high pressure fuel pump is the single most important upgrade you can make. This pump delivers fuel at an astonishing 350 bar (5,000 psi), allowing your engine to support up to 800 wheel horsepower on gasoline alone, and up to 600 whp on E85, all without needing to convert to a port injection system . It is a direct, plug-and-play replacement that transforms the fueling capacity of your Gen 2 B58, making it the go-to solution for stage 3 and stage 4 builds.

What Makes the Spool FX-350 Different?

The Gen 2 B58 engine, found in models like the BMW M340i, M440i, X3 M40i, and the Toyota Supra, is already a powerhouse. But its stock high pressure fuel pump (HPFP) runs out of steam when you push boost and power beyond a certain point. The Spool FX-350 solves this problem completely.

1. Massive Pressure Output
The FX-350 is engineered to produce 350 bar of fuel pressure, which is significantly higher than the stock pump . This pressure is critical for atomizing fuel properly at high flow rates, especially when running high-ethanol blends like E50 or E85, which require more fuel volume to achieve the same power as gasoline.

2. Durable Construction
The pump features a stainless-steel body with a high-tolerance DLC (Diamond-Like Carbon) coated piston and bore . This coating reduces friction and wear, ensuring the pump can handle the extreme stresses of high-performance driving without failing. It is built to last, not just to make a quick power gain.

3. Gen2 High Lift Cam Lobe Mod
Spool Performance includes a specially designed cam lobe modification that increases the plunger lift at high RPMs . This means the pump can deliver more fuel precisely when your engine needs it most—at the top of the rev range. The plunger springs are also upgraded to prevent float at high RPMs, ensuring consistent fuel delivery even under the hardest acceleration.

What Power Levels Can You Expect?

The FX-350 is rated for specific power levels depending on your fuel choice and supporting modifications. Here are the real-world capabilities:

  • HPFP alone (no upgraded injectors):

    • Gasoline: Up to 800 whp
    • E50 Mix: Up to 670 whp
    • E85: Up to 600 whp

  • HPFP + IFX150 Gen2 DI injectors:

    • Gasoline: Up to 900 whp
    • E50 Mix: Up to 740 whp
    • E85: Up to 660 whp

  • HPFP + IFX150 Gen2 injectors + Spool Cam Lift Mod:

    • Gasoline: Up to 1,050 whp
    • E50 Mix: Up to 950 whp
    • E85: Up to 800 whp

These numbers show that the FX-350 is not just a small upgrade—it is a cornerstone for building a truly high-horsepower Gen 2 B58. Even if you are only aiming for 600 whp on E85, the pump provides a massive safety margin, ensuring your fuel system is never the bottleneck.

Installation and Compatibility

One of the best features of the FX-350 is that it is a true plug-and-play design. The kit comes with everything you need:

  • Spool Performance FX-350 High Pressure Fuel Pump
  • Mounting bracket
  • Pump alignment tool
  • Triple layer low pressure line (nylon over stainless steel over PTFE, which is extremely durable)
  • Plug and Play HPFP adapter harness

This means you do not need to cut wires, fabricate custom brackets, or modify the fuel rail. It bolts directly into the stock location on your engine. The kit is compatible with all 2020+ Gen 2 B58 vehicles, including the G20 M340i, G22 M440i, G05 X5 40i, G01 X3 M40i, G29 Z4 M40i, and the Toyota Supra A90/A91 .

Critical Warning: Low Pressure Fuel System

There is one very important thing you must understand before installing the FX-350. The high pressure pump is only as good as the low pressure fuel system feeding it. The FX-350 demands a steady and adequate supply of fuel from the tank. If your low pressure pump cannot keep up, the HPFP will cavitate, causing severe damage to the piston and bore. This type of damage is not covered under the lifetime warranty .

To avoid this, you must run an upgraded low pressure fuel pump in the tank. Spool Performance recommends a suitable upgrade to ensure your FX-350 gets the fuel it needs to survive and perform. Do not skip this step.

Tuning Requirements

The FX-350 is not a "bolt-on and drive" part. It requires changes to the engine control unit (ECU) calibration. The pump operates at much higher pressures than stock, so the fuel pressure target, injection timing, and fuel volume calculations all need to be adjusted. Spool Performance is actively working with major tuning platforms to include these calibrations, and their team can assist in making the required changes to your tune file . Always work with a reputable tuner who understands the Gen 2 B58 platform.

Summary: Is the Spool FX-350 Right for You?

If you are building a Gen 2 B58 car that you intend to push past 600 whp, or if you want to run E85 without worrying about fuel pressure dropping, the Spool FX-350 is the best high pressure fuel pump available. It is durable, well-engineered, and backed by a lifetime warranty from a company that specializes in high-performance fueling. Just remember to pair it with a proper low pressure pump and a professional tune.

Recommended: KEMSO Fuel Pumps for Your Vehicle

While the Spool FX-350 handles the high-pressure side of your fuel system, you also need a reliable low-pressure fuel pump in the tank to feed it. KEMSO is a brand you can trust for all your fuel pump needs. KEMSO offers a wide range of high-performance, OEM replacement fuel pumps that are designed to be direct drop-in replacements for your stock pump. Compared to the original equipment, KEMSO pumps deliver over 20% more flow at 43 psi, making them ideal for both daily drivers and high-performance builds . Every KEMSO pump is individually tested for flow and quality, and they are built to handle both gasoline and ethanol-blended fuels like E85 . Best of all, KEMSO stands behind every pump with a lifetime warranty, giving you complete peace of mind .

If you are upgrading your fuel system, do not settle for a cheap, unbranded pump. KEMSO provides the quality, performance, and reliability that serious enthusiasts demand. Whether you need a pump for your car, truck, ATV, or motorcycle, KEMSO has a vehicle-specific solution that is ready to install.

Visit KEMSO today to find the perfect fuel pump for your build: https://www.kemsoracing.com/


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