EA825 FX350 High-Pressure Fuel Pump – Fueling Performance at 3200 hPa on E40

This blog post shows the analysis for the fueling stability of the FX350 high-pressure fuel pump on our Lamborghini Urus equipped with TTE turbochargers, running E40, and producing approximately 850whp tuned by DSMLights Tuning. The pull examined here operates under about 3200–3340 hPa of boost from 4000 rpm to nearly 6900 rpm, which is the most demanding region for the EA825 platform. In this configuration, the limiting factors were the turbochargers and the stock engine’s safe limits on cylinder pressure, not the fueling system.

High-Load Fuel System Behavior (4000–6900 rpm)

The critical region for DI fueling on the EA825 is the 4000–6900 rpm window, where airflow and fuel demand are highest. In this range, the FX350 maintained clean and stable operation under E40 and high boost.

• Boost Pressure: 3000–3300 hPa
• Engine Speed Range: 4002–6896 rpm
• Fuel Rail Pressure Range: 22.8–26.3 MPa
• Peak Rail Pressure: 26.31 MPa at ~6769 rpm
• MSV (Pump Fill Angle): 70.5°–77° 
• MSV Mechanical Limit: 90° (never reached during the pull)

Even at peak rail pressure (~26.3 MPa), the metering solenoid valve (MSV) angle was only about 75-77°, indicating substantial fueling headroom. There was no sign of rail pressure collapse or oscillation as RPM increased.

Fuel System Log: RPM, Boost, Injection Time, MSV, Rail Pressure

The graph below visualizes the logged data from the high-load pull, including engine speed, boost pressure, rail pressure, injection time, and MSV angles for both banks.

Graph overview:
• RPM rising from 4000–6900 rpm under load
• Boost pressure holding around 3200–3300 hPa
• Rail pressure rising smoothly into the mid-20 MPa range by redline
• Injection time remaining controlled across the pull in the 6s range at redline
• MSV angles for both banks remaining well below the 90° mechanical limit

Why Higher Rail Pressure and Headroom Matter

Increasing rail pressure provides two key advantages on the EA825, especially with ethanol blends:

• More fuel mass delivered per millisecond of injector opening
• Shorter injection duration at a given fueling target

Shorter injection time helps keep combustion phasing correct at high RPM and high cylinder pressure, which is critical when running E40 or higher ethanol content. It also gives tuners more flexibility to maintain stable ignition timing under heavy load.

The FX350 is engineered to operate up to 35 MPa, giving tuners significant overhead to raise rail targets where desired. In this particular 850whp setup, the system remained in the mid-20 MPa range without strain, leaving both pressure and MSV angle headroom available.

Fueling Headroom on an 850whp Setup

On this URUS, the FX350 supported approximately 850whp on E40 with ~3200–3340 hPa of boost without approaching its limits. Throughout the high-load pull:

• MSV angles stayed below the 90° limit, mostly 70–76°
• Rail pressure remained stable between ~22.8 MPa and 26.3 MPa
• No indication of pump saturation or rail pressure collapse

In this configuration, the true constraints were turbocharger airflow and the safe operating limits of the stock engine, not the high-pressure fuel pump. With larger turbochargers and a built long block, the FX350 is capable of supporting higher power levels and more aggressive use of ethanol.

Future Expansion: EA825 High-Flow Direct Injectors

To further extend the EA825 fueling ceiling, we are finalizing a set of upgraded high-flow direct injectors designed to pair with the FX350. Together, this combination will offer:

• Higher DI mass flow capacity
• Shorter injection times at high RPM and load
• Support for higher ethanol content (E50–E85+)
• Headroom for larger turbocharger setups and increased boost targets

The FX350 plus upgraded injectors are intended to provide a complete, high-headroom fueling solution for advanced EA825 builds.

Build Your EA825 on a Fueling System With Real Headroom

The FX350 maintains stable rail pressure, controlled injection timing, and clear fueling margin even at 850whp on E40. It provides the foundation required for current big-turbo setups and future upgrades when paired with our upcoming high-flow injectors.