Holley Dominator EFI Kit – LS1 Main Harness w/ Transmission Control (EV1 Injectors) - 550-656

The Holley Dominator EFI Kit (550-656) is the ultimate engine and vehicle management solution for high-performance LS builds. Designed for non-emissions street vehicles and race applications, the Dominator system offers nearly unlimited control over fuel, spark, transmission, boost, nitrous, water/meth injection, drive-by-wire throttles, and data acquisition—all from a single ECU.

Whether you’re running a naturally aspirated LS street car, a turbocharged drag setup, or a nitrous-assisted track build, the Dominator EFI system eliminates the need for multiple standalone controllers. With integrated electronic transmission control, advanced boost strategies, self-learning fuel tables, and extensive I/O expandability, this system adapts to virtually any performance combination you can imagine.

The ECU is fully potted for durability and can be mounted in the engine bay or interior, while sealed automotive-grade connectors ensure long-term reliability in demanding environments.

Key Features & Benefits

Engine & Fuel Management

• Individual cylinder fuel and spark control

• Self-learning fuel strategy that improves as you drive

• Supports naturally aspirated and boosted setups (1–7 bar MAP)

• E85 compatible

• Quick-Start strategies for improved cold starts

Transmission Control

• Integrated electronic transmission control

• Supports GM 4L60E & 4L80E transmissions

• Eliminates the need for a separate transmission controller

Boost, Nitrous & Power Adder Control

• Fully integrated boost control (time, RPM, gear, speed-based)

• 8-stage nitrous oxide control (wet or dry)

• Progressive control by time, RPM, or boost

• Integrated water/methanol injection control with precision flow scaling

• Boost Builder & anti-lag functionality

Data Logging & Visualization

• Built-in 4GB internal data logger

• Real-time strip chart and laptop gauge display

• Dual wideband O₂ sensor support (Bosch or NTK)

• Learn table smoothing and advanced data analysis tools

Drive-By-Wire & Safety

• Integrated drive-by-wire throttle control (up to two throttle bodies)

• Supports GM, Ford, Chrysler, and Nissan DBW throttle bodies

• Lean/rich safety cutoffs and system protection strategies

• Two-channel knock sensor inputs

Kit Includes

• Holley Dominator ECU

• ECU Power Harness

• LS1 Engine Main Harness

• EV1 Injector Harness

• Bosch Wideband Oxygen Sensor

• USB Communication Cable

• ECU Mounting Hardware

Technical Specifications

• Brand: Holley EFI

• Product Type: Dominator ECU / ECM / VCM

• Emission Code: 3 (Race / Uncontrolled Vehicles Only)

• CAN-BUS Support: Yes

• Boost Control: Yes

• Traction Control: Yes

• Self-Tuning: Yes

• Datalogging: Yes (4GB internal memory)

• Nitrous Control: Wet & Dry, Multi-Stage

• Ignition Control: Coil-per-cylinder supported

• Dimensions:

  • Length: 13.14"

  • Width: 6.10"

  • Height: 1.00" – 1.84"

• UPC: 090127137161

Emissions & Legal Information

This product is legal for sale and use only on Uncontrolled (Non-Emissions Controlled) Vehicles, including:

• 1965 and older U.S. California-certified vehicles

• 1967 and older U.S. federally certified vehicles

• 1967 and older foreign-manufactured vehicles

Not legal for use on emissions-controlled vehicles.