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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 550-936
Holley EFI Terminator X Universal MPFI Kit - Universal MPFI Main Harness
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£1,643.99 inc VAT£1,369.99 ex VAT -
Holley EFI 550-937f
Holley EFI Terminator X - Foxbody Mustang 5.0 EFI Kit - 1979-1993 Ford Mustang
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£1,699.00 inc VAT£1,415.83 ex VAT -
Holley EFI 550-937
Holley EFI Terminator X - Ford MPFI Kit - Universal MPFI Main Harness
Terminator X ECU's are designed to be mounted...
Part TypeFuel Injection System£1,643.99 inc VAT£1,369.99 ex VAT -
Holley EFI 550-1633-6
Holley EFI Terminator X Max GM Gen V LT4 Direct Injection Kit - Early
ECU is not recommended for marine applications, but...
Part TypeFuel Injection System£3,947.99 inc VAT£3,289.99 ex VAT -
MSD 2906
Atomic TBI, ECU Only - Atomic TBI, ECU, Early Version
**Early version using EV6 Injector Connector** **Later Version...
Part TypeEngine Control Module (ECM)£577.00 inc VAT£480.83 ex VAT -
MSD 8884
Harness, Dodge/Chrysler 98-03
Easy install for your MSD 6 series ignition...
Part TypeEngine Wiring Harness£88.00 inc VAT£73.33 ex VAT -
MSD 8877
Harness, MSD To Late Model '96-On GMs - MSD to Late Model 96-On GM Harness
Easy install for your MSD 6 series to...
Part TypeEngine Wiring Harness£95.99 inc VAT£79.99 ex VAT -
Holley EFI 550-1634-6
Holley EFI Terminator X Max GM Gen V LT4 Direct Injection Kit - Late
ECU is not recommended for marine applications, but...
Part TypeFuel Injection System£3,947.99 inc VAT£3,289.99 ex VAT -
Holley EFI 550-1624
Holley EFI Terminator X Max GM Gen V LT4 Direct Injection Kit - 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 550-1623
Holley EFI Terminator X Max GM Gen V LT4 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 550-919
TERMINATOR X MAX MPFI WTRANS LS1 WEV6 - Holley EFI Terminator X Max - LS1/LS6
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-916
Holley Terminator X Max ECU Kit - LS1 - 24X - W/ Trans Control
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-920
Holley EFI Terminator X Max - Gen IV 4.8/5.3/6.0 GM Truck Engines and LS2/LS3 - 58x Crank
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-918
Holley Terminator X Max ECU Kit - LS2/LS3 - 58X - W/ Trans Control
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-917
Holley Terminator X Max ECU Kit - Early GM Truck - 24X - W/ Trans Control
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,054.99 inc VAT£1,712.49 ex VAT -
Holley EFI 550-934
Holley EFI Terminator X Max - LS1/LS6 - 24x Crank
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,271.98 inc VAT£1,893.32 ex VAT -
Holley EFI 550-926
Holley Terminator X Max ECU Kit - LS1 - 24X - W/ DBW & Trans Control
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,271.98 inc VAT£1,893.32 ex VAT -
Holley EFI 550-935
Holley EFI Terminator X Max - Gen IV 4.8/5.3/6.0 GM Truck Engines and LS2/LS3 - 58x Crank
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,271.98 inc VAT£1,893.32 ex VAT -
Holley EFI 550-928
Holley Terminator X Max ECU Kit - LS3 - 58X - W/ DBW & Trans Control
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,271.98 inc VAT£1,893.32 ex VAT -
Holley EFI 550-927
Holley Terminator X Max ECU Kit - Early GM Truck - 24X - W/ DBW & Trans Control
Not recommended for 4x4 applications with electronic transfer...
Part TypeFuel Injection System£2,271.98 inc VAT£1,893.32 ex VAT -
Holley EFI 550-932
Holley EFI Terminator X Max - LS1/LS6 - 24x Crank
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 550-929
Holley Terminator X Max ECU Kit - LS1 - 24X - W/ DBW
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 550-933
Holley EFI Terminator X Max - Gen IV 4.8/5.3/6.0 GM Truck Engines and LS2/LS3 - 58x Crank
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 550-931
Holley Terminator X Max ECU Kit - LS3 - 58X - W/ DBW
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 550-950
Holley EFI Terminator X Max - Universal 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
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.



