LS vs LT engines: what changed?

"LS" usually means the Gen III (1997–2007) and Gen IV (2005–2020) small-blocks; "LT" means the Gen V engines from 2014 on (LT1, LT2, LT4, L83, L86, L8T…). From our engine table:

• Direct injection: 11 of 12 Gen V V8s in our table are direct-injected (DI, or port + direct on the LT5). Gen III/IV LS engines are port-injected.
• Compression: Gen V V8s run 10.00:1 to 11.50:1 compression, higher than most Gen III/IV engines.
• VVT and AFM: standard on most Gen V engines; on Gen III/IV only certain engines had them.
• Dimensions carried over: the 5.3 and 6.2 keep the same 3.78 in / 4.065 in bores and 3.622 in stroke as their LS predecessors.

For swappers: treat LT as its own family — check that the mounts, accessory drive, fuel system and engine controller you buy are listed for Gen V, not just "LS". Compare both in the donor finder.

Specs are GM ratings as published; power varied by year and vehicle. Confirm any engine by the RPO code on the glovebox/console sticker.