Holley EFI

Holley EFI — Standalone Engine Management & Fuel Injection Systems

Holley EFI is the dedicated engine management division of Holley Performance, producing the most comprehensive lineup of standalone ECUs, throttle body injection systems, and fuel injection conversion kits available for performance and classic engine applications. Whether you're converting a carbureted small block to modern EFI, managing a built LS swap, or running a full race engine management system on a dedicated track car, Holley EFI has a platform engineered for the application.

Sniper EFI — Self-Learning Throttle Body Injection

The Holley Sniper EFI system is the most popular carb-to-EFI conversion on the market. Replacing a standard four-barrel carburetor with a modern throttle body injection unit, the Sniper self-learns fuel maps using wideband O2 feedback — delivering cold-start reliability, consistent fuel delivery across all operating temperatures, and improved throttle response without requiring professional ECU tuning. The system is compatible with most existing intake manifolds and fuel systems with minimal modification.

Sniper Stealth configurations replicate the visual profile of a carburetor or Quadrajet for builds where period-correct appearance is a priority. Multi-port Sniper systems extend individual cylinder fuel delivery capability for higher-output applications where throttle body injection reaches its limits.

Terminator X — Standalone ECU for Engine Swaps

The Terminator X and Terminator X Max are Holley's purpose-built standalone ECU platforms for LS, LT, Coyote, and other modern engine swap applications. Terminator X manages fuel and ignition with self-learning capability and full Holley EFI software access for advanced tuning. The Terminator X Max adds integrated transmission control for 4L60E, 4L80E, 6L80E, and other popular automatics — providing complete powertrain management from a single ECU without additional transmission controllers.

Plug-and-play harness kits are available for the most popular engine and transmission combinations, significantly reducing wiring complexity for swap builds and allowing builders to focus on the mechanical side of the project rather than custom wiring.

HP EFI & Dominator ECU — Advanced Engine Management

For builds requiring advanced engine management beyond the Terminator X platform, Holley's HP EFI and Dominator ECU systems provide professional-grade control over fuel, ignition, boost, nitrous, transmission, and ancillary outputs. The Dominator is Holley's flagship race ECU, capable of managing the most complex engine combinations with full data logging, real-time tuning, and CAN bus integration for dash and data acquisition systems. Both platforms use Holley's EFI software for PC-based tuning with a large library of base maps and community tuning resources.

Fuel System Components

Holley EFI produces the supporting fuel system hardware required for EFI conversions — in-tank and inline fuel pumps, fuel pressure regulators, fuel rails, and complete returnless fuel system kits. Proper fuel system support is critical for EFI performance — the pump must maintain consistent pressure at all engine loads, and the regulator must hold the correct set point across the full operating range. Holley EFI fuel system components are matched to the flow and pressure requirements of their ECU and throttle body platforms.

Common Applications

Holley EFI systems cover GM LS (LS1 through LS9 and LSX), GM LT (LT1, LT4, LT5), Ford Coyote (5.0L Gen 1–3), Ford Modular, and classic carbureted V8 platforms across GM, Ford, and Mopar. Engine swap applications are the primary use case for Terminator X and HP/Dominator ECU platforms, while Sniper systems target carbureted classic and muscle car conversions where simplicity and self-learning capability are the priority.

Installation Notes

Sniper EFI installations require an in-tank or inline fuel pump capable of maintaining 58–60 PSI — most OEM electric pumps are insufficient and must be upgraded. Terminator X and standalone ECU installations require a complete engine harness, sensor suite, and initial base map calibration before startup. Holley provides detailed installation documentation, video resources, and tech support for all EFI products. Professional tuning is recommended for Dominator and HP ECU applications to maximize the capability of the platform.

Shop Holley EFI at Ozkonic Kustomz

Browse the full Holley EFI lineup below — Sniper systems, Terminator X, HP EFI, Dominator ECU, fuel system components, and accessories. If you need help selecting the right EFI platform for your engine, swap, or race application, reach out. We'll help you spec the right system and get your build running on modern fuel injection.