There’s a lot of confusion when it comes to GM’s modern LT engine family. You’ve probably heard terms like LT1, LT2, or LT4 thrown around, but what do they mean? The Gen V LT engine lineup represents the latest evolution of GM’s small-block V8s, following the Gen III and IV LS engines. While some enthusiasts may associate the LT nameplate with the classic small-blocks of the 1960s and ’70s, today’s LT engines are entirely distinct.

We previously broke down the LS engine codes in detail, covering everything from the LS1 to the LS9 and beyond. That article, which you can read here, helped clarify the Gen III and IV small-block family for beginners. Now, we’re diving into the modern Gen V LT engines to help you understand how GM’s newest small-blocks are coded and what makes them different.

What Makes LT Engines Different?

All LT engines belong to GM’s Gen V small-block family and introduce several advancements over the Gen III and Gen IV LS platforms. One of the most significant changes is the move to direct fuel injection. Unlike the LS engines’ port-injected setup, LT engines inject fuel directly into the combustion chamber. This provides better fuel atomization, increased efficiency, and improved emissions control, though it also complicates tuning and maintenance.

A look inside the LT2 engine.

LT engines also retain coil-on-plug ignition and aluminum cylinder heads across the board. Most are equipped with either Active Fuel Management (AFM) or the more advanced Dynamic Fuel Management (DFM), both of which deactivate cylinders under light load to improve fuel economy. Variable Valve Timing (VVT) is another standard feature, giving LT engines more precise control over valve timing across the RPM range for better performance and drivability.

The Odd Geminis

Technically, GM’s Gen V V8 lineup includes just traditional overhead valve variants. But the Gemini twins, specifically developed for the eighth-generation Corvette, carry the sequential RPO codes LT6 and LT7. A clean-sheet design that features dual-overhead cams, a flat-plane crank, and an 8,600 rpm redline, the LT6, created for the Z06, is the largest and most powerful naturally aspirated production V8 ever created. The LT7, created for the ZR1 and ZR1X, adds stronger internals, bigger combustion chambers and twin turbochargers that max out at 24 psi of boost.

Another major improvement in LT engines is their compatibility with GM’s newer automatic transmissions. From six-speed to ten-speed units, the LT engine family was built to integrate seamlessly with modern drivetrains, making them ideal for both OEM and custom swap applications.

Breaking Down The Codes

Here are the key LT engines to know:

• LT1: The 6.2L naturally aspirated Gen V V8 introduced in the 2014 Corvette and later found in the Camaro SS and some trucks. Makes 455 horsepower and 460 lb-ft.

• LT2: A refined version of the LT1 for the C8 Corvette, featuring a dry-sump oiling system and improved intake for mid-engine packaging. Makes up to 495 horsepower.

• LT4: A supercharged 6.2L monster with 650 horsepower and 650 lb-ft, found in the C7 Z06, Camaro ZL1, and third-gen CTS-V. Uses a 1.7L Eaton blower.

• LT5: The king of the Gen V OHV lineup, the LT5 was built for the C7 ZR1 with a larger 2.65L supercharger and 755 horsepower. It also includes port injection in addition to direct injection.

• LT6: The LT6 is a clean-sheet design developed for the C8 Z06. With dual-overhead cams, a flat-plane crank, and an 8,600 rpm redline, it pumps out 670 horsepower and 460 lb-ft of torque.

• LT7: Featured in the C8 ZR1 and ZR1X, the LT7 adds stronger internals, bigger combustion chambers, port injection, and twin turbochargers to the LT6’s dual-overhead cam construction. Horsepower is 1,064 in the ZR1 and 1,250 in the ZR1X.

• L83/L84: The 5.3L truck versions of the Gen V V8. L83 is Gen V’s base truck engine, and L84 features DFM. Power ranges from 355 to 383 horsepower.

• L86/L87: 6.2L truck engines similar to the LT1 but tuned for torque and utility. L86 came first; L87 added DFM and improved cooling.

• L8T: A 6.6L heavy-duty Gen V V8 used in HD Silverado/Sierra trucks. The L8T features an iron block, direct injection, and its design prioritizes performance over high revs.

LT vs. LS: The Key Differences

While the LT and LS engines share architecture, they’re not directly interchangeable. The biggest difference is fuel delivery; direct injection requires a high-pressure fuel pump driven off the camshaft. That affects cam design, cylinder heads, and intake manifolds. Additionally, the LT family uses a different front accessory layout and often includes AFM/DFM systems, which must be deleted or tuned out in performance builds.

Now that you understand the lineup, decoding GM’s LT engines doesn’t seem so intimidating. Whether you’re swapping one into a project car or just trying to understand what’s under your hood, this knowledge gives you the tools to speak fluent Gen V.