Next-Gen Duramax Keeps Its 305 Horsepower — and That's Fine

The optional 3.0-liter I6 LZ0 turbodiesel Duramax in the 2027 trucks will make 305 horsepower and 495 lb-ft of torque, according to sources familiar with the matter cited by GM Authority. If those figures sound familiar, they should. They're identical to what the diesel delivers in the current 2026 Silverado and Sierra, where the LZ0 is rated at 305 horsepower at 3,750 rpm and 495 pound-feet at 2,750 rpm.

In other words, the generational changeover reportedly leaves the diesel untouched. No power bump, no torque bump, no drama.

On paper, a carryover diesel looks underwhelming next to the gasoline fireworks GM has lined up for 2027. But the LZ0 didn't need the help. It's already among the strongest powertrains in the lineup, and per the article it posts the highest towing rating of the bunch for the 2026 model year at 13,300 pounds, edging out the L87 V8 at 13,200 pounds.

Buyers cross-shopping the diesel are chasing torque and towing, both of which it already delivers in spades. Leaving it alone is a defensible call.

For context, the outgoing 2026 Silverado 1500 fields four engines: the turbocharged 2.7-liter I4 L3B TurboMax (310 hp, 430 lb-ft), the naturally aspirated 5.3-liter V8 L84 (355 hp, 383 pound-feet), the naturally aspirated 6.2-liter V8 L87 (420 hp, 460 lb-ft), and the LZ0 Duramax.

The two V8s are the ones getting retired. The 5.3-liter L84 and 6.2-liter L87 will step aside for a pair of new Gen 6 Small Blocks: a 5.7-liter V8 wearing the L76 code and a 6.6-liter V8 badged L78. Both RPO codes are throwbacks, dusted off for the new generation.

GM says the L78 will be "the most powerful naturally aspirated V8 in the full-size pickup segment," a claim the automaker has made without publishing exact figures. GM Authority reports that language likely points to something north of 470 hp, though GM hasn't committed to a number yet. The TurboMax four-cylinder is also getting enhanced for the new generation, per GM.

So the story here is a familiar one for anyone tracking full-size trucks: the halo numbers go to the gas V8s, while the diesel quietly does the heavy lifting it was always good at. The LZ0 doesn't get a headline, but it keeps the tow rating that matters. For a segment that treats spec sheets like leaderboards, holding serve counts for something.

Whether the carryover diesel stays priced as a premium option worth its upcharge is a separate question, and one GM hasn't answered. For now, the takeaway is straightforward: the 2027 pickups reinvent nearly everything under the hood except the engine that arguably needed it least.

[Image: General Motors]

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