How to Run an LT Gen V Engine on an LS Gen IV Computer - ICT Billet

How to Run an LT Gen V Engine on an LS Gen IV Computer

August 22, 2025
Cuota Correo Correo electrónico

Want LT Gen V power with LS Gen IV tuning simplicity? You can run an LT on an LS ECU without tearing the engine apart. Just a few key changes and you’re ready to go.

Whether you’re a die-hard SBC fan or loyal to LS/LT, this swap is worth looking at. Salvage yard builds are all about creativity — mixing and matching parts that weren’t meant to live together. Sure, some people will say,

“It’s not worth it,” or “The LT is perfect already,” or “Why not just tune the DI system?”

That’s fine if you’ve got deep pockets and experience in tuning DI (aka direct injection), but for many of us, wiring and modern electronics are the intimidating part.

Here’s the good news: with the right adapters, running an LT on an LS ECU is as simple as throwing a LS Holley Terminator X system on a LT engine. The LT already has the same LS 58X crankshaft reluctor wheel signal and camshaft signal, so the LS ECU can read them. You just need to connect them — which is where ICT Billet comes in.

We make the wire connectors and harnesses to adapt these three sensors:

Note: LT engines don’t use ignition coil sub-harnesses like LS engines do, so you’ll need ICT Billet part WEC0I35X2 or equivalent to connect the coil packs to the main harness.

Mechanical Differences & Required Changes

1) Camshaft

If you’re keeping the stock LT cam, then you will need to lock out the camshaft phaser with BTR-AMP-VVTLOLT.

2) Direct Injection Removal

Since you’re going to be running port injection, the LT’s DI system needs to be blocked off with the following parts.

  • Dummy injectors: Measure the lower Teflon seal on your factory injectors —
    • 7.5 mm = use kit 551333-L83 (2020 & older, most cases)
    • 6.0 mm = use kit 551333-L84 (common on newer L84/L86)
      GM has mixed injector sizes within the same RPO codes, so measure before ordering.
  • Remove the valley cover and DI high pressure fuel pump lifter. Plug the lifter hole with 551965-PLUG.
  • Add a new valley cover (551168) with oil pressure sensor adapters (551166), or use just use 551171 plate if you want to keep the stock valley cover.

3) Intake Manifold & Port Injection

Choose the correct ICT Billet intake adapter, unless you are going carbureted.  If so then ignore this step and use Holley’s carb intake HLY-300-940BK:

Then install your LS intake manifold, LS throttle body, LS fuel rails, and injectors.

4) Transmission

The LS, LT, and SBC/BBC use slightly different bellhousing bolt patterns (mainly the top bolt position):

  • LS = 12 o’clock
  • LT = slightly right of 12 o’clock
  • SBC/BBC = 2 o’clock

Just leave that one bolt out, it’s fine.

For torque converter to flexplate connection, use the following two parts:

Both LS and LT use M10 bellhousing bolts.

5) Engine Mounts

LS mounts won’t bolt directly to the LT block.  This is fixed with a simple adapter plate to add the LS engine mount hole locations to the LT engine.  Thus converting the LT to now have the available 4 bolt pattern on each side of the engine.

·         Engine Mount Adapter 551367

6) Accessory Drive & Water Pump

First lets start with the most universal LT water pump that GM used.  This pump has the central pulley location, similar to LS engines, which allows the greatest amount of accessory brackets to fit your ride.

·       WAT311
Accessory Brackets

7) Exhaust Headers

LT exhaust ports are different from LS.  You will need to source LT headers for your build.

Conclusion 

Running an LT Gen V engine on an LS Gen IV ECU is surprisingly straightforward. There’s no crank swap, no complicated direct injection electronics, and no mystery wiring.  Just the right adapters, brackets, and a few key parts.

Luckily, we've got those key parts together so you can ensure you're covered with just one click!

Our L83/L86 - Gen V Engine to Gen IV ECM Conversion Kit | L83-LS-CNVKIT01.

With this setup, you get modern LT performance with the tuning simplicity of the LS. Whether you’re building a daily driver or a track car, this swap lets you keep things simple, reliable, and easy to maintain.

 

Author: Alan Burdue