What Do GM’s New 5.7L and 6.7L V8 Rumors Mean for the 2027 Silverado and Sierra 1500?

Gas trucks are not dead. Far from it. But the next generation of Chevrolet and GMC Small Block V8 engines is “bigger” news for those in the market looking for more power.

While everyone on the internet screams about EVs, General Motors quietly spent close to two billion dollars freshening engine plants for a sixth-generation small block V8 that starts production in 2027. You do not pour that kind of money into Flint, Tonawanda, and St. Catharines if you plan to walk away from gas power.

That spending is what lit the fuse on the two big rumors you keep seeing: a 5.7-liter and a 6.6- to 6.7-liter V8 for the next Silverado and Sierra.

I’ve owned a 5.3 that did everything I asked, two 6.2s that absolutely rip, and I have driven the 2.7 TurboMax enough to know it is a great daily. I am not here to cheerlead for one motor. I want to lay out what we really know, what is still guesswork, and where a future plug-in hybrid might fit into the picture.

>> Join the discussion in our 2027 Silverado 1500 & Sierra 1500 Forum <<

Quick reference: what we know about GM’s next-gen V8s

Last verified: May 27, 2026. Specs marked “speculative” or “expected” are educated estimates based on the current lineup, GM’s stated efficiency targets, and supplier leaks; GM has not released official numbers.

What’s real and what’s rumor

Here are the only details that matter as of today:

• GM has publicly confirmed a sixth-gen small block V8 family for full-size trucks and SUVs.
• GM says production begins in 2027.
• GM has not confirmed any displacement, power rating, or trim mix.

Everything else about “5.7” and “6.7” comes from leaks and off-the-record chatter.

The first wave of reporting pointed to two truck engines:

• Around 5.7 liters as the volume V8
• Around 6.6 liters as the big gas option

That lines up neatly with what we have now. Think of the 5.7 as a modern replacement for the 5.3, and the 6.6 as the spiritual successor to the 6.2.

Then a second leak hit, this time out of Corvette world. An internal parts catalog listing showed an LS6 at 6.7 liters (409 cubic inches) with an aluminum block, pushrods, and both direct and port injection. That 6.7 number spread into truck circles in a hurry.

Put those two streams together and you get the rumor stew we have today:

“Next-gen trucks get a 5.7 and a 6.7.”

But is it that simple? Here’s what we know:

• A 5.7 for half-tons is very believable.
• A larger V8 in the 6.6–6.7 neighborhood is also believable.
• Whether that exact 6.7 Corvette-grade engine lands in a Silverado or Sierra is not confirmed at all.

What the new V8s will probably look and feel like

GM is not throwing out the small block recipe. The plant upgrades are for the same basic style of engine: blocks, cranks, heads, cams, rods. That points straight at another pushrod OHV family, not a fancy DOHC truck motor.

So figure on:

• Cam-in-block, two-valve heads, compact package
• New combustion chamber design and better cooling control to chase power, mpg, and emissions at the same time
• Cylinder deactivation sticking around, with updated hardware to make it live longer
• A real chance that the big motor gets dual injection like the Corvette leak suggests, which helps both emissions and long-term deposit control

I would not plan my life around a turbo V8 or a built-in hybrid motor until we see real filings or hardware. GM is talking publicly about better combustion and thermal management, not boost.

Power that actually makes sense

Let’s anchor this against the current half-ton lineup:

• 2.7 TurboMax: 310 hp / 430 lb-ft
• 5.3 V8: 355 hp / 383 lb-ft
• 6.2 V8: 420 hp / 460 lb-ft
• 3.0 Duramax: 305 hp / 495 lb-ft

With those numbers in mind, here is what I personally see power outputs a sane GM engineer is going to target.

Rumored 5.7-liter

• Around 365–410 hp
• Around 395–450 lb-ft

Enough to clearly beat the 5.3, feel stronger down low, and still sit below the top dog gas engine.

Rumored 6.6–6.7-liter

• Around 430–520 hp
• Around 480–580 lb-ft

That keeps it ahead of the current 6.2, closer in feel to the Duramax on torque, while still leaving room for the diesel to own towing efficiency and range.

Of course, these are wide speculative ranges, not hard leaked dyno sheets. They match what GM is promising publicly: more power, better mpg, lower emissions, all at the same time.

From a seat-of-the-pants view:

• If you like your 5.3, a 5.7 should feel like “the same idea, but better everywhere.”
• If you love the 6.2, the bigger Gen-6 engine is the one you will watch closely.

Where a plug-in hybrid Silverado/Sierra fits in

There is one more piece to this story. Last year we broke down GM’s work on a plug-in hybrid HD powertrain that blends a gas engine with a battery pack and electric drive. That article is here:

Next-Gen Silverado HD EV & Hybrid: What We Know So Far

The GM Defense program appears aimed at heavy duty first, but it gives us a clear look at GM’s thinking. Pair a combustion engine with electric assist for launch torque, short EV runs, and better city mpg without jumping to a full EV.

Now line that up with timing:

• 2027 is when the new V8s start production.
• Truck life cycles run long.
• Once the engines are validated in the real world, a plug-in setup built around one of them is an obvious next step.

So while 2027 is shaping up as “new small blocks” for the Silverado and Sierra 1500, 2028 starts to look like a realistic window for a PHEV half-ton. That would let GM lean on the new V8 hardware and bolt an electrified layer on top once the bugs are worked out.

Nothing official on that yet, but when you look at the history of how GM typically rolls out new product and the V8 timeline together, that path makes the most sense.

What this means if you are actually buying one

Here is how I’d look at it as an owner:

• If you daily a 5.3 now and it does the job, a 5.7 with more torque and smarter fuel control is the natural upgrade.
• If you live for the way a 6.2 pulls, the bigger Gen-6 V8 is your next target, as long as the towing and cooling package matches your use.
• If uptime is money for you, be careful with first-year engines. Let 2027 run, watch what breaks, then order a 2028 or 2029.
• If you are PHEV-curious, keep 2028 in the back of your mind. A plug-in 1500 built around one of these V8s fits the pattern GM is already setting and uses tech already on the shelf from the Silverado EV and Sierra EV, already on the market.

Frequently asked questions

Is Chevrolet bringing back the 5.7 engine?

Effectively, yes , but not the classic 5.7L 350 small block from the Vortec era. GM has confirmed a sixth-generation small block V8 family for 2027 production, and the most consistent leaks point to a 5.7-liter displacement as the volume engine, replacing the current 5.3L L84. It will be a modern OHV pushrod V8 with current GM technology, direct injection, cylinder deactivation, modern emissions controls — not a revival of the old 350.

Will the 2027 Silverado have a V8 engine?

Yes. GM has publicly committed to gas V8 power in the 2027 Silverado 1500 and Sierra 1500. The current 2.7L TurboMax four-cylinder will likely continue as the base engine, but V8 power is staying. The expected lineup is the new 5.7L V8 as the volume option, a larger 6.6L (possibly 6.7L) V8 as the premium gas option, and the 3.0L Duramax inline-six diesel continuing as the efficiency play.

How much horsepower does a 2027 GM 5.7 engine have?

GM has not released official numbers. Based on the current 5.3L L84 (355 hp / 383 lb-ft), supplier leaks, and GM’s stated efficiency targets, realistic estimates land between 365–410 hp and 395–450 lb-ft of torque. Dealer communications circulating in spring 2026 have cited approximately 400 hp as the working target. Treat all of these as estimates until GM publishes official figures.

What is the new GM motor for 2027?

It’s the sixth-generation small block V8 family, an evolution of the current Gen V architecture (the L84 5.3L and L87 6.2L), not a clean-sheet design. The new family will use the same fundamental layout (pushrod OHV, two-valve heads, cam-in-block) with updated combustion chambers, improved thermal management, refined cylinder deactivation hardware, and likely dual injection on the larger displacement. GM has invested approximately $2 billion across its Flint, Tonawanda, and St. Catharines engine plants to support production.

What’s a better engine, a 5.3L V8 or 2.7L turbo?

It depends on use. The 2.7L TurboMax (310 hp / 430 lb-ft) actually has more torque than the current 5.3L V8 (355 hp / 383 lb-ft) and is competitive in real-world acceleration. The 2.7 is also more fuel-efficient in light-duty use. The 5.3L V8 is the better choice for sustained towing, hot climates, hard work, and owners who plan to keep the truck past 150,000 miles where V8 durability advantages compound. The forthcoming 5.7L V8 will likely shift the equation further in favor of the V8 by adding power without sacrificing efficiency.

Will the 2027 Silverado look different from the 2026?

Patent drawings published by GM in late 2025 show a refreshed front-end design with revised lighting and grille treatments. The bones of the current T1XX platform are expected to carry over, with a styling refresh rather than a clean-sheet redesign. Major changes are likely to focus on the powertrain (new V8 family) and interior technology, with exterior changes more incremental.

What’s the difference between the new 5.7L V8 and the old Chevy 5.7L 350?

Almost everything. The classic Chevy 5.7L was the 350-cubic-inch Gen I and Gen II small block produced from 1967 through the Vortec 5700 (L31) in 2002. The new 2027 5.7L is part of an entirely different architecture — the sixth-generation small block, descended from the LS / Gen V / Gen VI line. They share displacement and “small block” branding, and that’s about it. The new engine has modern direct injection, electronic throttle, cylinder deactivation, and emissions controls the old 350 never had.

Staying current as the story develops

We will keep tracking every filing, leak, and official announcement inside the community:

• Discussion hub for the trucks: 2027 Silverado 1500 & Sierra 1500 Forum
• Engine deep dive and rumor control: Sixth Generation Small Block Forum

Gas power is not going away in the next Silverado and Sierra. It is evolving, and if GM sticks the landing, these new V8s plus a future plug-in option could give truck buyers more real choice, not less.

This is an evolving story. We update this article as new information confirms or disproves the rumors. Most recent update: May 27, 2026.

Zane Merva

Zane Merva is the Executive Editor of GM-Trucks.com and the President of the New England Motor Press Association (NEMPA). A veteran automotive journalist with over 26 years of experience, Zane is a designated ‘Car Talk’ Expert and has been a contributor to The Boston Globe. He possesses a unique evaluative perspective, having road-tested more than 2,000 vehicles across every major manufacturer. While he is a recognized authority on General Motors truck platforms—including the Silverado, Sierra, and Colorado—his expertise is grounded in decades of deep competitive analysis that few in the industry can match. His commentary has been featured by major OEMs and media outlets, including Hyundai and PR Newswire