Package/bundle discounts may be available, contact us at sales@efisupply.com for custom system quotes


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Note: Many different Holley Terminator EFI systems and options are available, please be sure to scroll down to see all listed items and Holley HPEFI products.

Not sure which aftermarket EFI system is best for you? Click here to view our aftermarket EFI buyer's guide.

Looking for a summarized feature listing? Click here to view a list of features of our aftermarket efi systems



  • 4-barrel carburetor to fuel injection conversion kits for 250-600 HP V8 engines
  • No laptop required
  • Fits any square (Holley 4150™) flanged intake
  • Self-tunes while you drive
  • 950 CFM Throttle Body with CFD computer designed venturi taken from Holley’s NASCAR® throttle body
  • 80 lb/hr injectors (@ 43 PSI)
  • Connections for Ford, GM TH350 and 700R4, and other transmission linkages
  • Provides ignition timing control on engines with GM Computer-Controlled Small Cap HEI and Ford TFI distributors (requires adapter)
  • Self-tunes to deliver the perfect air/fuel mixture in real time for optimized fuel economy and power
  • Virtually maintenance free - keeps your vehicle reliable and ready to drive
  • Patent pending annular discharge fuel ring for maximum flow and optimum fuel atomization - No restrictions or delay in fuel flow like booster designs
  • Trouble-free performance with today’s fuels –eliminate vapor lock and fuel varnish problems
  • Serviceable sensors integrated into throttle body and pre-wired for a simple one-click connection - don’t get stranded by competitive designs
  • ECU fully potted and sealed for protection from vibration, dust and moisture
  • Terminator ECU can be EASILY updated to Holley “HP” ECU specs with a free online software download.
  • ECU can then be used for LSX, boosted, nitrous, and many other applications in the future as you desire!
  • Trouble-free performance with today’s fuels - put an end to vapor lock and fuel varnish problems!


All EFI systems purchased from efisupply.com include a ECU calibration matched to your application. We have a large library of naturally aspirated and power adder calibrations and are likely to have the file you need. If we don't already have it, we'll work with you to develop a new calibration for your combination.


Holley Terminator EFI Systems (click description to see kit contents)
P/N 550-405, Terminator EFI - w/ raw cast TBI
P/N 550-405K, Terminator EFI - w/ raw cast TBI & fuel system
P/N 550-406, Terminator EFI - w/ hardcore gray TBI
P/N 550-406K, Terminator EFI - w/ hardcore gray TBI & fuel system
We work hard to provide competitive pricing on our entire offering of aftermarket electronic fuel injection systems and components, if you find anything we sell somewhere else for less contact our sales staff at sales@efisupply.com and we'll do out best to match or beat their price!


Take control of your engine with Terminator X! Don't settle for a factory ECU with a cumbersome tuning interface when you can have complete control of your engine, self-learning fuel strategies and the proven, race-winning technology of Holley EFI at a budget-friendly price! Terminator X features real-time fuel learn, high impedance injector drivers, an integrated 1bar MAP sensor, and 4 programmable inputs and outputs. The inputs and outputs are ideal for electric fans, boost control solenoids, progressive nitrous control, and much more. Terminator X comes fully loaded with base maps for common V8 engine combinations to get you out of the garage and on the road/track fast. The 3.5" touch screen LCD handheld contains an easy to use calibration wizard as well as tuning and gauge display functions. Also included is Holley EFI's industry-leading, easy to use software suite that allows full laptop access for advanced users. Whether you are building a budget beater or a boosted race car, Terminator X has the features and technology you need at a price that won't break the bank!
  • Features:

    • Plug and play Domestic V8 engine control, such as conventional push rod Chevrolet and Chrysler engines.
    • Includes EV1 Injector Harness
    • High Impedance Injector Drivers will safely power most Stock injectors, and Holley EFI Injectors. Injector support chart provided in the instructions (Will not control Low Impedance Injectors)
    • Bosch LSU 4.9 wideband to relay AFR information to the ECU for accurate reading and precise tuning control.
    • Built in 1bar MAP Sensor, vacuum hose adapters included (1/8th – ¼ and 3/16ths) - or for Boosted applications, you can disable the internal MAP sensor, and utilize an external MAP Sensor, the harness comes with the connector terminated, making the install
    • MAP Sensor vacuum hose adapters (1/8th – ¼ and 3/16ths)
    • Plug and plug ignition capability with Dual Sync and HyperSpark Distributors, adapter 558-323 required for HyperSpark Distributors.
    • 4 Inputs – 12v, Ground, 5v, and Frequency, for things such as additional pressure sensors, or activation triggers for nitrous activation, or a trans brake
    • Boost Control – Boost vs Time, Boost vs Gear, Boost vs RPM, Boost vs Speed, Boost Safeties
    • Nitrous Control – Single Channel of Wet or Dry, Progressive or Non-Progressive, Rich/Lean Safeties, and target Closed Loop AFR
    • Advanced Tables – 4x 1D Tables, 1x 1D per Gear Table, 4x 2D Tables, 1x 2D per Gear Table, can be used for any custom tables you can dream up, such as Flex Fuel Sensor Offset Table, or a custom fuel or oil pressure safety!
    • On-Board Diagnostic LEDS for: ECU Power – Engine Run – Wideband Status – TPS Calibration – Crank Signal –Cam Signal. Allow you to identify any Critical engine issues at a glance
    • The included 3.5" Touchscreen Handheld contains a calibration wizard, that allows you to quickly build a base tune for any domestic V8 engine. Additionally the handheld provides internal data-logging and a fully customizable gauge display.
    • The compact ECU size allows you to mount it virtually anywhere. Remember, diagnostic LEDS must face up!
    • Plug and play compatible with more Holley EFI accessories such as; analog style gauges, shift lights, various modules, and coming soon, 12.3" digital dash support!
    • Free EFI Tuning Software for complete control of your Terminator X power plant
Holley Terminator X EFI Systems
P/N 550-950, TERMINATOR X UNIVERSAL MPFI KIT, drive by wire (DBW)


Click here to download a Holley EFI Product Catalog