WATCH: As Diesel Prices Push $10 A Gallon GM Launches The 8.3 Liter Mongoose Turbo Diesel
Posted on 9/22/2026 by Agent009
Detroit's heavy-duty truck segment has a new displacement champ. General Motors teased an 8.3-liter mammoth of a turbo diesel V8 by means of a short video that stars a mongoose and a scorpion. To be sold under Duramax branding, the newcomer will be offered in the 2027 Chevrolet Silverado HD and technically similar 2027 GMC Sierra HD.
The order guides for the 2500 and 3500 series reveal two regular production option codes that are completely new for the 2027 model year. L8S replaces the L8T as the standard 6.6-liter gasoline V8 small block, with General Motors listing direct injection and variable valve timing. The other RPO code that captured our attention is L6P, and neither order guide reads anything about its displacement.