8.3 Duramax diesel engine news
The gist
GM teased an all-new 8.3-liter Duramax diesel V8, codenamed Mongoose, for 2027 HD trucks.
It targets Ford's Scorpion, but GM released no power or torque figures yet.
How it unfolded
- Sep 21, 2026GM announced the new Duramax diesel 8.3-liter V8 engine in a YouTube video; aside from the displacement, no engine specs were provided.
- Sep 21, 2026GM's teaser video showed a bow-tie-eyed Mongoose attacking and killing a Scorpion walking in an oval.
- Sep 21, 2026Order guides for the 2500 and 3500 series reveal two new regular production option codes for the 2027 model year: L8S replaces the L8T as the standard 6.6-liter gasoline V8 small block, and L6P is listed with no displacement.