Holley Terminator X LS kit — 58x, EV1 (550-910T)

What Terminator X is

Terminator X is Holley’s entry-level standalone engine management for LS engines. It replaces the factory computer outright, which is why it is the usual answer for an LS swap: one controller and one harness that plug into the engine, instead of a factory ECU and its wiring transplanted from a donor car.

This version, 550-910T, is for engines with a 58x crank trigger and EV1 injectors. It comes with a USB/CAN tuning cable in place of Holley’s 3.5-inch handheld screen, so setup and tuning happen on a laptop in Holley’s free software, which ships with base calibrations for naturally aspirated and boosted LS combinations.

What it controls

Fuel and spark, with a real-time learning fuel strategy that trims the fuel table toward the air-fuel ratio you target. Four programmable inputs and four outputs handle the things a swap usually needs — electric fans, a boost solenoid, nitrous activation, a trans brake — and there are custom tables for anything else, such as a flex-fuel offset or an oil-pressure safety.

• Boost control by time, gear, rpm or speed, with safeties
• Nitrous: one channel, wet or dry, progressive or not, with rich and lean safeties
• Diagnostic LEDs for ECU power, engine run, wideband, TPS, crank and cam signal
• Plug-and-play with Holley’s digital dashes, gauges and shift lights

Will it fit your engine? Check these three things

Crank trigger, injector connector and throttle. Get any one of them wrong and the harness does not plug in. If the answer to any of these is no, Holley makes a version that fits — ask us which one before you buy.

• 58x crank reluctor and 4x cam. Gen IV LS engines including the LS3 are 58x; 24x engines need a different kit.
• EV1 injector connectors. Running EV6 / USCAR injectors? Holley’s EV6 version of this kit is a different part number.
• Cable throttle. This kit does not run a drive-by-wire throttle body.

Self-learning gets it running. A calibration makes it safe at full load

The learning fuel strategy is genuinely good at getting an engine started and close on fuel. It does not decide how much timing the engine will take, what happens when the tank is hot, or how the car behaves at the top of third gear with the throttle pinned — and those are the parts that hurt engines.

We install Terminator X, build or finish the harness, and calibrate it on our hub dyno with the full sheet at the end. Shop labor is $265 an hour and the calibration is priced on the standalone tuning page; the hours depend on the car, so we quote the job against yours.