Item # 22861 BRAND: Holley

Holley HP EFI 4bbl Multi Port Fuel Injection System 550-810

HP EFI Multi-Port Fuel Injection System V8 4 bbl, Single Plane Small Block Chevy, Early to Late Heads
HP EFI Multi-Port Fuel Injection System V8 4 bbl, Single Plane Small Block Chevy, Early to Late Heads
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HP EFI Multi-Port Fuel Injection System V8 4 bbl, Single Plane Small Block Chevy, Early to Late Heads

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Holley HP EFI 4bbl Multi Port Fuel Injection System 550-810

Product Overview:


HP Multi-Port EFI systems for small or big block Chevys are ready for the street or strip with the simple swap of an intake! Whether you have a stock engine, crate or custom-built engine, HP Multi-Port systems can help you maximize performance! By utilizing a laptop (or the optional 5.7" full color touch screen LCD) along with the HP's self-tuning capabilities, the HP Multi-Port EFI system will get you to the cruise or race in no time. HP Multi-Port Systems include: intake manifold, billet throttle body, ECU, wiring harness, fuel rails, and related small parts. Fuel pump and injectors are available separately to fit your requirements.


  • “Quick Start” ignition and fueling strategy for LS x Engines
  • Data Logger. Scalable axes, Smoothing, Multiple graph view ability, Pre-defined notes fields and many more
  • Strip Chart Real-Time Data Viewer
  • Integrated Boost Control - Boost vs Time, Boost vs Gear (Time or RPM), Boost vs RPM, Boost vs Speed, Launch control. Boost launch builder, Over-boost safeties, Boost scramble
  • Traction Control - Power reduction via timing, nitrous percentage or boost (Requires Davis Technologies Holley Module)
  • “Quick Start” fueling for all engines
  • Option for VE based fueling strategy
  • Fuel Map and Learn Function Smoothing
  • Configurable User Password Protection
  • Fully Configurable lap top Gauge Panel
  • Optional 5.7” full-color touchscreen LCD allows easy on-the-fly tuning,data-logging or can be used as an easy to see graphical gauge panel
  • Eight sequentially driven 8:2 peak and hold injector drivers, capable of driving up to 16 low or high impedance injectors as a standard feature. Multiple staged injector strategies
  • Eight channel Distributorless Ignition (DIS)outputs capable of directly driving “Smart” ignition coils or Holley DIS coils. Will drive 2 wire coils with the addition of PN 554-112 high current coil driver module
  • Plug and Play control of factory GM 24x and 58x LSx engines
  • Integrated single channel wide band oxygen sensor control. Works with NTK or Bosch sensors
  • Internal data-logging standard with a huge 2GB of memory
  • 4 Stage progressive nitrous control
  • Turbo boost control
  • Integrated water/methanol injection control
  • Self-tuning fuel table strategy greatly simplifies tuning process
  • Individual cylinder fuel and spark control allows you to unlock your engine’s potential
  • Works with 4, 6, 8 cylinder engines
  • Unique lb/hr based fueling strategy greatly simplifies and commonizes tuning
  • Advanced idle, closed loop, and enrichment strategies allow for very stable operation
  • ECU is fully potted and can be mounted in the engine compartment or interior
  • Sealed automotive and marine grade connectors
  • Allows for use of common OEM sensors as well as customer sensor calibration input
  • Ignition Plug and Play with GM 24x and 58x LSx engines, GM HEI, Ford TFI, magnetic and hall effect trigger, and other ignition systems. New Plug and Play applications in process. Custom settings can be configured to allow many other applications
  • 1-5 Bar MAP sensor capability
  • Two channel knock control sensor Inputs for both one or two wire knock sensors
  • Dedicated fuel and oil pressure inputs
  • Controls both stepper and PWM Idle Air Control (IAC) motors
  • Speed density, Alpha-N, or combination fueling strategies
  • 4 Programmable high or low Pulse Width Modulated (PWM) outputs and 4 fully configurable inputs can be configured for use
  • 4 Stage nitrous oxide control
  • Fully featured nitrous control eliminates the need for a separate nitrous controller device
  • Can be configured “Wet” or “Dry” with closed loop feedback


1 Year Manufacturers Warranty


Brand: Holley EFI<br> Emission Code: 3<br> Product Type: HP EFI Kit<br> Part Number: 550-810<br> <b>EMMISIONS</b><br><br> <p>This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles and Racing Use Only Vehicles.</p><br /> <p>The following vehicles are considered Uncontrolled (Non-Emissions Controlled) Vehicles:</p><br /> • 1965 and older U.S. manufactured California Certified vehicles<br /> • 1967 and older U.S. manufactured Federally Certified vehicles<br /> • 1967 and older Foreign manufactured vehicle<br /><br /> The following vehicles are considered Racing Use Only Vehicles: <br /><br /> • Racing Use Only Vehicles are vehicles that are used exclusively for competition and that are not registered and that may never be used on the street<br /><br /> <b><u>WARNING: It is against the law to install this part on an Emissions Controlled Vehicle</u></b><br /><br /> The following vehicles are considered Emissions Controlled Vehicles: <br /><br /> • 1966 and newer U.S. manufactured California Certified vehicles<br /> • 1968 and newer U.S. manufactured Federally Certified vehicles<br /> • 1968 and newer Foreign manufactured vehicle

In the Box


(1) Holley HP EFI 4bbl Multi Port Fuel Injection System 550-810

Guides & Accessories


<p><a href="" target="_blank"><i><b>Instructions for 550-810</b></i></a></p><br /> <p><a href="" target="_blank"><i><b>Crank & Cam Sensor Requirements for 550-810</b></i></a></p><br /> <p><a href="" target="_blank"><i><b>ECU Warning for Part# 550-810</b></i></a></p><br /> <p><a href="" target="_blank"><i><b>Information for Part# 550-810</b></i></a></p><br /> ***The following sensors are included: *TPS - IAC - MAP - CTS - MAT - Wideband O2 *ECU is certified to ISO 8846, SAE J1171 & United States Coast Guard Requirements for Ignition Protection & Fire Resistance. *Holley HP EFI systems are equipped with 4 programmable inputs and 4 programmable outputs that are ideal for most vehicles with a single power adder. This feature allows the user to configure the system to support a wide range of controls including boost control, progressive nitrous, water/meth injection, speed inputs, fuel pump control, AC inputs, timing retard inputs and various other uses. When selecting an ECU, users need to ensure their planned controls can be run with the 4 inputs and 4 outputs as certain combinations may use more I/Os than are available. If more I/Os are required, users should choose the Dominator VMS. MPFI Systems do not include injectors or a fuel pump. They need to be sized for the application and can be purchased seperately from Holley. *These kits require the use of a small diameter distributor, such as a small cap GM HEI or most MSD distributors. A large cap GM HEI will not fit with these kits.


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Questions & Answers

1-ST DOSE this come with 2 02 sensors To read each bank 2- If I have intake with Mutli port Injection TBI fuel rails Would the ECU and wiring harness be bought seperatly If it would work

Asked by: Dave73
Holley sells it as an entire kit in this instance not separate.
Answered by: Anonymous
Date published: 2023-03-29
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Holley HP EFI 4bbl Multi Port Fuel Injection System 550-810
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