GM's New LS6 Small-Block V8: A Nerdy Look at What's Inside and Where It's Headed

• GM's sixth-generation small-block starts with the new 6.7-liter LS6 V8.
• The LS6 will make its way into the Corvette Stingray as well as the reborn Grand Sport and new Grand Sport X models.
• Expect this modern V8 to show up in more GM products soon, including the Chevy Silverado and GMC Sierra pickups, as well as the automaker's full-size SUVs.

By now you've probably heard that the Corvette Grand Sport is back and Chevy is expanding the name to span its own mini lineup of two models: the rear-drive Grand Sport and the hybrid all-wheel-drive Grand Sport X, which outdoes and replaces the E-Ray. Both GS models will use a new small-block V8 called LS6, the first of GM's sixth generation, that will also replace the LT2 in Corvette Stingrays starting next year.

Because new small-blocks don't come along very often, and since this mill will find its way into more mainstream models like the Chevy Silverado and GMC Sierra pickups, plus the Chevy Suburban and Cadillac Escalade, we're taking a deeper dive into what makes this new engine tick and how it will stack up to what powers competitor sports cars, trucks and SUVs. First, some nerding out.

Inside the LS6 small-block

According to tradition, for GM to call this new pushrod engine a small-block, it had to have 4.4-inch bore centers — that's the distance from the center of one cylinder to the adjacent cylinder's. While that spec hasn't changed, plenty of others have. For instance, the LS6 keeps the LT2's 103.25-millimeter bore diameter but ups the stroke length from 92 mm to a numerically pleasing 100 mm. That results in a displacement of 6.7 liters (the LT2's was just 6.2 liters) — or 409 cubic inches for fans of classic GM metal and the songs it inspired.

Inside each of those eight roughly 837-cc pots, you'll find forged pistons connected to forged rods. The cylinder heads have a new two-piece water jacket to keep heat in check, apparently necessary to allow for a wild compression ratio of 13.0:1. Lubrication has also been improved compared to the LT2's setup.

To jam more air into those larger cylinders, the engineers increased the size of the throttle body — 95 mm vs. 87 mm on the LT2 — and refined the intake plumbing to speed up flow. This engine also marks the first use of both port and direct fuel injection; the LT2 had only direct injection. GM calls the new setup PDI.

Final totals: 535 horsepower and 520 lb-ft of torque. Chevy claims the LS6 makes more torque than any other production naturally aspirated V8.

Sports car rivals

Yes, we're about to compare the Corvette's engine to those of cars costing at least twice as much as a base Corvette Stingray. (It's not the first time, nor will it be the last.) That's the thing about the Corvette; it's a bargain with no real direct competitor in terms of price. Performance, however? The 'Vette has plenty of that, and the LS6 will only add to it.

The table below includes the current Stingray's LT2 for reference and pits the LS6 — both unassisted and with an electric boost — against the powertrains from the Porsche 911 Carrera S and the hybrid 911 GTS. We threw in the McLaren GTS' 3.8-liter V8 because that engine sits in the middle of the car. And for fun.

The LS6 is certainly the biggest engine of this bunch and the only one that does its job without forced induction. This big-displacement engine nets very competitive horsepower numbers and a whole lot of torque. GM hasn't divulged how much torque the front electric motor adds to the system total, but the engine alone already has more than the hybridized 911 six-cylinder. Assuming weight stays roughly the same, the new Stingray and Grand Sport should reach 60 mph in less than the 3.4 seconds it takes for the current base Corvette with the Z51 package. The Grand Sport X will certainly outdo the E-Ray's 2.8-second run.

Also of note: Unlike today's Stingray, which offers a performance exhaust that boosts output to 495 hp and 470 lb-ft, the LS6 will come just one way. Buyers will, however, be able to spec a four-cannon center-exit exhaust like those on the Z06 and ZR1, but its advantages are aesthetic and aural, not performance-enhancing.

New trucks and SUVs versus competitors

Now let's look at where the sixth-gen small-block is headed next. After the Corvette, we expect the new V8 to appear in two redesigned full-size trucks, the 2027 Chevrolet Silverado (pictured above) and the 2027 GMC Sierra. From there it's a natural extension that Chevy, GMC and Cadillac will introduce new SUVs — Tahoe, Suburban, Yukon, Escalade — that will also take advantage of the big engine.

The engine we see in those products will be a little different than the LS6 and likely carry a different name. GM tends to tune its truck and SUV engines a little differently from those in the Corvette, so we're estimating output based on today's engines. A new smaller-displacement V8 is likely to join the 6.7-liter in the trucks — today's L84 displaces 5.3 liters — but GM isn't talking about that yet.

And then there are the competitors, many of which have moved away from V8s, although Ram is running back to its Hemi. These are not necessarily the largest-displacement engines offered by each manufacturer, but they represent the top of their mainstream portfolios. (We're ignoring stuff like the Cadillac Escalade-V's supercharged 6.2-liter and the blown V8 in the Ford F-150 Raptor R.)

GM's current 6.2-liter is already competitive. Whatever the new 6.7-liter truck engine is called, it should outdo all current domestic rivals except for the high-output versions of Stellantis' Hurricane, but who knows how long that engine will last in Rams. Among V8s, the sixth-gen engine should be king — big displacement will do that.

The Corvette is just the first of what will be a series of new GM vehicles powered by the sixth-generation small-block. It's an interesting time for engines in general, especially big V8s, and this new engine family (and the investment behind it) is a sign that internal combustion isn't going away anytime soon.