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ECU & Engine Management
ECU & Engine Management — Standalone EFI and LS Swap Solutions Engine management is the brain of a modern fuel-injected powertrain. The ECU processes data from dozens of sensors, calculates optimal fuel delivery and ignition timing thousands of times per...
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Holley EFI 550-942
Holley EFI Terminator X Max - Universal MPFI Kit - Universal MPFI Main Harness
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-959
Holley EFI Terminator X Max - Universal MPFI Kit - Universal MPFI Main Harness
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,271.98 inc VAT£1,893.32 ex VAT -
Holley EFI 550-945
Holley EFI Terminator X Max - Ford MPFI Kit - Universal MPFI Main Harness
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-944
Holley EFI Terminator X Max - Ford MPFI Kit - Universal MPFI Main Harness
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-943
Holley EFI Terminator X Max - Ford MPFI Kit - Universal MPFI Main Harness
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-1611
Holley EFI Terminator X Max GM Gen V LT Direct Injection Kit - Late
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£3,406.99 inc VAT£2,839.16 ex VAT -
Holley EFI 550-1631
Holley Terminator X for GEN V LT Engines - Late DI
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£3,677.99 inc VAT£3,064.99 ex VAT -
Holley EFI 550-1621
Holley Terminator X Max Kit - GEN V LT Late
ECU is not recommended for marine applications, but...
Part TypeFuel Injection System£3,406.99 inc VAT£2,839.16 ex VAT -
Holley EFI 550-1610
Holley EFI Terminator X Max GM Gen V LT Direct Injection Kit - Early
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£3,406.99 inc VAT£2,839.16 ex VAT -
Holley EFI 550-1620lsd
Holley EFI Terminator X Max GM Gen V LT Direct Injection Kit - Early
ECU is not recommended for marine applications, but...
Part TypeFuel Injection System£3,406.99 inc VAT£2,839.16 ex VAT -
Holley EFI 550-1630
Holley Terminator X Max for GEN V LT Engines - Early DI
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£3,677.99 inc VAT£3,064.99 ex VAT -
Holley EFI 550-1620
Holley EFI Terminator X Max GM Gen V LT Direct Injection Kit - Early
ECU is not recommended for marine applications, but...
Part TypeFuel Injection System£3,406.99 inc VAT£2,839.16 ex VAT -
Holley EFI 554-153
Holley EFI Terminator X Max Service ECU - Compatible with all Terminator X Harnesses
ECU is not recommended for marine applications, but...
Part TypeEngine Control Module (ECM)£1,433.99 inc VAT£1,194.99 ex VAT -
Holley EFI 550-1601
Holley EFI Terminator X GM Gen V LT Direct Injection Kit - Late
No Drive-by-Wire or Transmission Control
Part TypeFuel Injection System£2,859.98 inc VAT£2,383.32 ex VAT -
Holley EFI 550-1600
Holley EFI Terminator X GM Gen V LT Direct Injection Kit - Early
No Drive-by-Wire or Transmission Control
Part TypeFuel Injection System£2,859.98 inc VAT£2,383.32 ex VAT -
Holley EFI 554-152
Holley EFI Terminator X Service ECU - Compatible with Terminator X Harnesses
ECU is not recommended for marine applications, but...
Part TypeEngine Control Module (ECM)£1,015.99 inc VAT£846.66 ex VAT -
Holley EFI 550-1219
Holley EFI Terminator X - Ford Mod Motor 4V Kit - Compatible w/ Stock Coils and EV6 injectors
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£2,136.98 inc VAT£1,780.82 ex VAT -
Holley EFI 550-1218
Holley EFI Terminator X - Ford Mod Motor 4V Kit - Compatible w/ Stock Coils and EV1 injectors
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£2,136.98 inc VAT£1,780.82 ex VAT -
Holley EFI 550-1217
Holley EFI Terminator X - Ford Mod Motor 2V Kit - Compatible w/ Stock Coils and EV6 injectors
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£2,136.98 inc VAT£1,780.82 ex VAT -
Holley EFI 550-1216
Holley EFI Terminator X - Ford Mod Motor 2V Kit - Compatible w/ Stock Coils and EV1 injectors
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£2,136.98 inc VAT£1,780.82 ex VAT -
Holley EFI 550-1221
Holley EFI Terminator X - Ford Mod Motor 2V/4V Kit - Compatible w/ Smart coils and EV6 injectors
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£2,136.98 inc VAT£1,780.82 ex VAT -
Holley EFI 550-1220
Holley EFI Terminator X - Ford Mod Motor 2V/4V Kit - Compatible w/ Smart coils and EV1 injectors
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£2,136.98 inc VAT£1,780.82 ex VAT -
Holley EFI 550-1319
Holley EFI Terminator X Max - 4V Ford Mod Motor - Stock Coils
ECU is not recommended for marine applications, but...
Part TypeFuel Injection System£2,487.98 inc VAT£2,073.32 ex VAT -
Holley EFI 550-1318
Holley EFI Terminator X Max - 4V Ford Mod Motor - Stock coils
ECU is not recommended for marine applications, but...
Part TypeFuel Injection System£2,487.98 inc VAT£2,073.32 ex VAT -
Holley EFI 550-1317
Holley EFI Terminator X Max - 2V Ford Mod Motor - Stock Coils
ECU is not recommended for marine applications, but...
Part TypeFuel Injection System£2,487.98 inc VAT£2,073.32 ex VAT
ECU & Engine Management — Standalone EFI and LS Swap Solutions
Engine management is the brain of a modern fuel-injected powertrain. The ECU processes data from dozens of sensors, calculates optimal fuel delivery and ignition timing thousands of times per second, and adjusts in real time to maintain performance, efficiency, and engine protection across all operating conditions. Choosing the right engine management system — and ensuring it's correctly wired and calibrated — is one of the most consequential decisions in any performance build or engine swap project.
With over 200 engine management products from Holley EFI, Haltech, MSD, and related specialists, Billy's Speed Shop stocks a comprehensive range of ECUs, engine wiring harnesses, and control modules for everything from plug-and-play LS swap solutions to fully configurable standalone systems capable of managing the most complex race engine combinations.
Standalone EFI Systems — Complete Engine Management
Standalone EFI systems replace the factory engine management entirely, providing full user-configurable control over fuel delivery, ignition timing, launch control, boost control, and ancillary functions. The major advantage of a standalone system over a factory ECU is the ability to tune freely without dealer-level tools, integrate non-factory sensors and components, and expand the system's capabilities as the build evolves.
For LS swap applications, standalone systems eliminate the complexity of adapting a factory LS ECU to a non-factory vehicle — avoiding the need for security bypass modules, instrument cluster integration challenges, and the limitations of tuning a system that wasn't designed for aftermarket modification. A quality standalone ECU provides a clean, known starting point with full tuning capability from day one.
Engine Wiring Harnesses — Clean Installation
The engine wiring harness connects the ECU to every sensor, actuator, and control system on the engine. On LS swap and EFI conversion projects, a quality harness is the difference between a professionally executed installation with reliable long-term function and a problematic build where the wiring is a constant source of intermittent faults and troubleshooting. Our harness range includes pre-terminated, labelled harnesses designed for specific engine and ECU combinations, eliminating the time and risk associated with building a custom harness from scratch.
Engine Control Modules and Brackets
Factory LS ECUs — used in applications where a factory-based tune is preferred — require correct mounting solutions that protect the module from vibration, heat, and moisture. ECU mounting brackets position the module securely in a suitable location within the engine bay or interior, with appropriate ventilation and protection. Wiring harness extensions and bulkhead connectors facilitate clean harness routing through firewalls and between engine and interior.
EFI Conversion Kits
Complete EFI conversion kits provide everything needed to convert a carburetted engine to fuel injection in a single package — throttle body, ECU, harness, sensors, and fuel system components selected and matched for compatibility. These kits dramatically simplify what would otherwise be a complex multi-component sourcing exercise and are available in configurations suited to both traditional carburetted V8 engines and LS-based builds.



