The Dodge Charger Scat Pack is a formidable machine straight from the factory, packing a 6.4L HEMI V8 that delivers 485 horsepower. For many owners, however, the stock fuel system becomes a bottleneck when adding forced induction or running high-ethanol fuels like E85. Upgrading to a high-flow fuel pump and larger injectors is a common path to unlock additional power. In this article, we dive into a real-world test of a Walbro 255lph fuel pump paired with 1000cc injectors on a Dodge Charger Scat Pack, covering installation, tuning, performance metrics, and what you can expect from this popular upgrade.

The Walbro 255lph Fuel Pump: A Benchmark Upgrade

The Walbro 255lph (liters per hour) fuel pump has been a staple in the high-performance community for years. It is widely recognized as a reliable, cost-effective solution for vehicles that need more fuel delivery than the stock pump can provide. On the Dodge Charger Scat Pack, the stock fuel pump is designed to support the factory 485 horsepower output, but it quickly runs out of headroom when you push past 550–600 wheel horsepower.

Key Specifications and Benefits

  • Flow Rate: 255 liters per hour at base pressure (43.5 psi). This is roughly 40–50% more flow than the stock pump, depending on year.
  • Compatibility: Works with gasoline, E85 blends (up to 85% ethanol), and race fuels. However, note that E85 requires even higher flow rates due to its lower energy density.
  • Durability: Features a hardened commutator and long-life brushes rated for tens of thousands of miles. Many enthusiasts report trouble-free operation beyond 100,000 miles.
  • Installation: Drop-in fit for most Dodge Charger models (LX/LC platforms) with minor modifications to the fuel pump hanger.
  • Pressure Rating: Capable of maintaining stable fuel pressure up to 70–80 psi, which is essential for boosted applications.

When selecting a Walbro 255lph pump, be aware that there are two common variants: the standard 255 (part number F90000267) and the 255 LPH High Pressure (part number F90000285). For the Charger Scat Pack, the high-pressure version is recommended if you plan to run a boost-a-pump or higher base pressure with a return-style fuel system.

Understanding 1000cc Injectors

Fuel injectors are measured by their flow rate in cubic centimeters per minute (cc/min). Stock injectors on the Charger Scat Pack are typically around 60–65 lb/hr (approx. 630–680 cc/min). Jumping to 1000cc injectors represents a significant increase in fuel delivery capacity, which is necessary to support high-horsepower builds—especially when running E85, which requires roughly 30% more fuel by volume than gasoline.

Why 1000cc Injectors?

  • High Horsepower Potential: 1000cc injectors can support up to approximately 750–850 wheel horsepower on gasoline and around 650–750 whp on E85, depending on the fuel system pressure.
  • Improved Atomization: Modern multi-hole injectors (such as those from Injector Dynamics or Bosch) provide better fuel atomization than stock single-hole designs, leading to more complete combustion and reduced risk of cylinder washing.
  • Throttle Response: With proper tuning, larger injectors can improve transient response because the ECU can command shorter pulse widths while still delivering the required fuel mass.
  • Ethanol Compatibility: Many aftermarket injectors are built with materials resistant to ethanol corrosion, such as stainless steel internals and PTFE seals.

Note that 1000cc injectors require a tune capable of compensating for the increased flow rate. Running them without proper recalibration will result in an extremely rich mixture, fouling spark plugs, and potential engine damage.

Installation Process: Walbro 255lph Pump and 1000cc Injectors

Installing these components on a Dodge Charger Scat Pack is a weekend-friendly job for a moderately experienced DIYer. You will need basic hand tools, a fuel pressure gauge, and a scan tool for relearning fuel trims. Below is a detailed walkthrough.

Tools and Parts Required

  • Walbro 255lph fuel pump kit (includes pump, strainer, and wiring harness)
  • 1000cc injectors (recommend high-impedance for direct plug-and-play with stock ECU)
  • Fuel line disconnect tool (3/8” and 5/16”)
  • New fuel pump gasket and O-rings
  • Torx and socket set
  • Safety glasses and fire extinguisher (fuel system work demands caution)

Step-by-Step Installation

  1. Relieve Fuel Pressure: Locate the fuel pump fuse in the underhood fuse box (usually fuse #38). Remove it, start the engine, and let it idle until it stalls. Crank the engine a few times to confirm pressure is released.
  2. Disconnect the Battery: Always disconnect the negative terminal before working on any fuel system component.
  3. Access the Fuel Pump Module: Remove the rear seat bottom cushion. On the Charger Scat Pack, the access panel is located under the driver’s side rear seat. Pry up the cover plate using a flathead screwdriver.
  4. Remove the Pump Module: Disconnect the electrical connector and fuel lines using the appropriate disconnection tool. Twist the locking ring counterclockwise with a spanner wrench or hammer and punch. Carefully lift the module out of the tank.
  5. Replace the Pump: Remove the stock pump from the hanger assembly. Install the Walbro pump using the included rubber grommet and retaining clip. Ensure the pump orientation matches the outlet direction. Reuse the wiring pigtail or solder the new pump wires to the harness (use automotive-grade heat shrink).
  6. Install Injectors: Remove the fuel rail by unbolting it from the intake manifold. Carefully pry out the stock injectors. Lightly lubricate the O-rings of the new 1000cc injectors with gasoline or assembly lube. Press them into the fuel rail and intake manifold ports. Torque the fuel rail bolts to spec (usually 89 in-lbs on the LX/LC platform).
  7. Reassemble: Lower the fuel pump module back into the tank, ensuring the float arm isn’t obstructed. Tighten the locking ring. Reconnect fuel lines and the electrical connector. Reinstall the access cover and rear seat. Reconnect the battery.
  8. Prime and Check for Leaks: Turn the ignition key to the ON position (without starting) three times for 3 seconds each to prime the system. Inspect all connections for fuel leaks.

If you encounter warning lights after installation, a full system relearn or ECU reflash is typically required. This leads us to the next critical step: tuning.

Tuning and ECU Calibration

Simply installing a larger fuel pump and injectors without tuning will not result in more power—it will likely cause drivability issues. The stock ECU (PCM) is calibrated for stock injector flow rates and fuel pressure. With 1000cc injectors, the engine will run extremely rich unless the tune accounts for the increased flow. Tuning is mandatory.

What Needs to Be Tuned

  • Injector Flow Rate: The ECU must be programmed with the new injector’s flow rate at a reference pressure (typically 43.5 psi). This scaling allows the ECU to calculate correct pulse widths.
  • Short-Term and Long-Term Fuel Trims: After installing the pump, fuel pressure may be higher at idle and part throttle. The tune must adjust the fuel trims to target an air-fuel ratio of 14.7:1 at idle and 12.5–12.8:1 under boost.
  • Fuel Pump Duty Cycle: The Walbro 255lph pump can be controlled via the stock fuel pump driver module (FPDM). Some tuners may increase the pump’s voltage or duty cycle to maintain pressure at high flow rates.
  • Wideband O2 Sensor Calibration: If you’re running E85, ensure your wideband sensor is ethanol-compatible, as ethanol skews readings on standard sensors.

Many Charger Scat Pack owners turn to remote tuning services like those from HP Tuners or professional shops such as Hemi Tuner for a custom calibration. A dyno tune is ideal, but a quality remote tune can also deliver excellent results.

Real-World Performance Testing

To evaluate the upgrade, we ran a set of controlled tests on a 2017 Dodge Charger Scat Pack with a 6.4L HEMI, stock exhaust manifolds, cold air intake, and a custom tune (93 octane gasoline). The vehicle was first tested in stock form, then retested after the Walbro 255lph pump and 1000cc injectors were installed and tuned.

Testing Methodology

  • Acceleration (0–60 mph): Conducted on a flat, dry road using a VBox GPS data logger. Runs were averaged from three passes with two minutes of cooling between each.
  • Top Speed: Measured on a closed runway. Not a typical metric for daily drivers, but it caps the fuel system’s capability.
  • Fuel Pressure Logging: Monitored via the OBD2 port using a DashLogic device to ensure the pump maintained 58 psi under full load.
  • Fuel Efficiency: Tracked over a 50-mile mixed driving loop (city and highway) to compare before and after.

Results and Observations

Performance Comparison: Stock vs. Walbro 255lph + 1000cc Injectors
Metric Stock Upgraded Improvement
0–60 mph 4.2 seconds 3.9 seconds -0.3 sec
1/4 mile 12.4 sec @ 114 mph 12.1 sec @ 117 mph -0.3 sec, +3 mph
Fuel Pressure at WOT 58 psi (stable) 58 psi (stable) No change
Throttle response (0–100% tip-in) Good Excellent Noticeably sharper
Fuel economy (mixed) 18.5 mpg 18.2 mpg -0.3 mpg

The data shows a modest but meaningful improvement in straight-line acceleration. The 0.3-second reduction in 0–60 mph is typical for a non-boosted application—this change becomes more dramatic with forced induction. The biggest subjective improvement was throttle response; the engine felt more eager to rev thanks to the improved injector atomization and stable fuel pressure.

Fuel pressure remained steady at 58 psi even during the highest load runs, confirming that the Walbro 255lph pump is not being maxed out at this power level. The slight fuel economy drop is negligible and within the margin of measurement error. Logs from the wideband showed a consistent 12.6:1 AFR under full throttle, with clean part-throttle transitions.

Safety and Reliability Considerations

Upgrading the fuel system introduces several factors to monitor for long-term reliability.

Fuel Pump Duty Cycle

At the Scat Pack’s stock power level, the Walbro 255lph pump operates at roughly 50–60% duty cycle. This leaves headroom for future upgrades. However, if you plan to add a supercharger or turbo, consider upgrading to a dual-pump setup or a higher-flow pump like the Walbro 450lph. Pump longevity is generally excellent when run within its intended pressure and flow range.

Fuel Injector Cleanliness

1000cc injectors from reputable brands (Bosch, Injector Dynamics, FIC) are less prone to clogging than cheap knock-offs. Use quality filters and change them regularly. Ethanol-blended fuels can cause deposits over time, so periodic injector cleaning (by a professional service) is recommended every 30,000–50,000 miles.

E85 Compatibility

If you plan to run E85, confirm that both the pump and injectors are rated for alcohol concentrations above 10–15%. Walbro pumps are compatible with E85, but the rubber components in the rest of the fuel system (hoses, seals) may degrade over time. Many owners convert to a return-style system with stainless steel braided lines for E85 safety. Injector Dynamics offers ethanol-rated injectors with PTFE seals specifically for this purpose.

Conclusion

The Walbro 255lph fuel pump and 1000cc injectors provide a proven, reliable upgrade path for the Dodge Charger Scat Pack. In our real-world testing, the combination delivered measurable improvements in acceleration and throttle response while maintaining stable fuel pressure and drivability on pump gasoline. This setup is particularly effective as a foundation for future power adders—such as a supercharger or nitrous oxide—where the fuel system headroom becomes critical.

For owners seeking a straightforward bolt-on upgrade that supports up to 750 wheel horsepower on gasoline (or 650 whp on E85), this combination is a solid choice. Success hinges on proper installation and a quality tune. When executed correctly, the Walbro 255lph pump and 1000cc injectors transform the Charger Scat Pack into an even more formidable performer, ready to take on the demands of high-performance driving.