Rx-7 Ls Swap Fuel System Setup: Choosing the Right Injectors, Pumps, and Regulators

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The RX-7 LS swap is a popular modification among car enthusiasts looking to enhance performance. One of the most critical components of this swap is the fuel system. Proper selection of injectors, pumps, and regulators is essential for optimal performance and reliability.

Understanding the Fuel System Requirements

Before diving into the specifics of injectors, pumps, and regulators, it is important to understand the fuel system requirements for an LS swap in an RX-7. The engine’s power output, intended use, and tuning will all influence your fuel system choices.

  • Engine power output
  • Type of fuel (pump gas, race gas, E85)
  • Intended use (street, track, racing)

Choosing the Right Injectors

Injectors play a vital role in delivering the correct amount of fuel to the engine. When selecting injectors for your RX-7 LS swap, consider the following:

  • Flow Rate: The injector flow rate should match the engine’s horsepower goals. A common range for LS swaps is between 60 to 100 lb/hr.
  • Type: High-impedance injectors are typically preferred for LS applications due to compatibility with factory ECU systems.
  • Brand: Choose reputable brands known for quality and reliability, such as Bosch, Injector Dynamics, or DeatschWerks.

Injector Sizing Calculation

To accurately size your injectors, you can use a simple formula:

  • Horsepower = (Injector Flow Rate * Number of Injectors * Duty Cycle) / 1000
  • Consider a duty cycle of around 80% for optimal performance.

Selecting the Fuel Pump

The fuel pump is responsible for delivering fuel from the tank to the engine. An adequate pump is crucial for maintaining fuel pressure and flow. Here are key factors to consider:

  • Flow Rate: Ensure the pump can support your horsepower goals. A common flow rate for LS swaps ranges from 255 LPH to 450 LPH.
  • Type: In-tank pumps are generally quieter and more efficient, while external pumps can handle higher pressures.
  • Compatibility: Ensure the pump is compatible with your fuel type and can be easily installed in the RX-7 fuel tank.

Some popular fuel pump options for RX-7 LS swaps include:

  • Walbro 255 LPH
  • Walbro 450 LPH
  • DeatschWerks DW300
  • Radium Engineering Dual Pump System

Choosing the Right Fuel Pressure Regulator

The fuel pressure regulator maintains consistent fuel pressure to the injectors. Selecting the right regulator is essential for optimal engine performance. Consider the following:

  • Adjustability: Look for adjustable regulators to fine-tune fuel pressure based on your setup.
  • Pressure Range: Common pressure settings for LS engines range from 43.5 psi to 60 psi.
  • Return Style vs. Returnless: Determine if your system will use a return line or if a returnless setup is more suitable.

Here are some recommended fuel pressure regulators for LS swaps:

  • Holley EFI Regulator
  • Aeromotive A1000
  • DeatschWerks Adjustable Regulator

Installing the Fuel System

Once you have selected the appropriate components for your fuel system, the installation process begins. Follow these steps for a successful installation:

  • Remove the Old Fuel System: Safely drain and remove the existing fuel system components from the RX-7.
  • Install the Fuel Pump: Follow manufacturer instructions for installing the new fuel pump into the tank.
  • Set Up Fuel Lines: Use high-pressure fuel lines and fittings to connect the pump to the fuel rail.
  • Install the Fuel Pressure Regulator: Mount the regulator and connect it to the fuel rail and return line if applicable.
  • Test the System: Before starting the engine, check for leaks and ensure proper fuel pressure.

Tuning the Fuel System

After the installation, tuning the fuel system is crucial for achieving optimal performance. Consider the following:

  • ECU Tuning: A proper tune is necessary to ensure the engine runs efficiently with the new fuel system.
  • Monitoring: Use wideband O2 sensors to monitor air-fuel ratios and adjust as needed.
  • Dyno Testing: Consider a dyno session to verify performance and make any final adjustments.

In conclusion, setting up a fuel system for an RX-7 LS swap requires careful consideration of injectors, pumps, and regulators. By understanding your requirements and making informed choices, you can ensure a reliable and high-performing fuel system.