More Cubes, More Power: Meet GM’s Gen 6 Small Block

Nick Adams September 24, 2026 4 min read 0

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General Motors is finally putting some real numbers behind the Gen 6 small-block V8s that will power the redesigned 2027 Chevrolet Silverado 1500 and GMC Sierra 1500. While the new engines have been part of the conversation for a while, GM had held back some of the finer details, including the official regular production option codes for the new 5.7-liter and 6.6-liter V8s. Now we know what these new small-blocks are bringing to the table, and the numbers show a pretty serious jump over the engines they replace.

Meet The Gen 6 L76 And L78

The smaller of the two new engines carries the L76 designation and replaces the outgoing 5.3-liter small-block. The 5.7-liter engine features a 3.780-inch bore paired with a 3.858-inch stroke and produces 402 horsepower at 5,500 rpm and 428 lb-ft of torque at 4,300 rpm.

For buyers looking for more displacement, the L78 adds another 50 cubic inches via a larger 4.065-inch bore. The 6.6-liter engine produces 481 horsepower at 5,800 rpm and 501 lb-ft of torque at 4,000 rpm, making it the most powerful naturally aspirated V8 gasoline engine currently offered in the half-ton segment.

Both engines make significant gains over the V8s they replace. The 5.7-liter L76 beats the previous 5.3-liter engine by 47 horsepower and 45 lb-ft of torque. The 6.6-liter L78 improves on the outgoing 6.2-liter by 61 horsepower and 41 lb-ft.

More Air, More Fuel, And More Oil Control

GM also gave the new V8s more capability to move air. Higher compression, larger throttle bodies, and new intake manifolds with tuned runners handle the additional airflow, while both engines now use dual injection.

That means the Gen 6 small-blocks combine direct fuel injection and port fuel injection. According to the information surrounding the new engines, this dual-injection setup is also purportedly the reason GM moved away from a traditional engine oil dipstick in favor of an oil level sensor.

The oil level sensor isn’t exactly a new idea. German manufacturers have used similar systems for years now for several reasons, including manufacturing modularity and strict crankcase ventilation requirements, while also directing customers back toward the dealership when something goes wrong.

Underneath, the Gen 6 small-block architecture was introduced by the LS6 for the 2027 model year Corvette Stingray, Grand Sport, and Grand Sport X. The Corvette also brought back the 409-cubic-inch displacement, with that 6.7-liter engine remaining exclusive to the C8 Corvette starting with the 2027 model year.

All three members of the Gen 6 family share 4.40-inch bore-center spacing, a dimension GM has continued to use across millions of small-block engines produced since the 1950s.

The Truck Numbers Matter

The new engines aren’t just about dyno numbers. GM has also released towing and payload figures for the 2027 half-ton trucks. A properly equipped 2027 Silverado 1500 with the 5.7-liter engine can tow up to 13,700 pounds, while the 6.6-liter version maxes out at 9,700 pounds. The Sierra 1500 is rated for 13,500 pounds with the 5.7-liter and 9,400 pounds with the 6.6-liter. Maximum payload follows a similar pattern. The 5.7-liter Silverado 1500 is rated for 2,170 pounds, compared with 1,510 pounds for the 6.6-liter version.

Despite the move away from the traditional dipstick, GM is carrying over Dynamic Fuel Management cylinder deactivation technology. DFM uses eight solenoids in the valley, just like the previous generation, to shut down any combination of cylinders as needed to help save fuel. The oiling system also receives a major overhaul. The Gen 6 small-block uses a continuously variable oil pump that adjusts oil flow and pressure according to driving conditions instead of switching between two fixed stages. That revised system is backed by larger lifter galleries, bigger main-bearing feeds, and an oil cooler built directly into the oil pan.

With the new 5.7-liter L76 and 6.6-liter L78, GM is giving the 2027 Silverado 1500 and Sierra 1500 a pair of naturally aspirated V8s with more displacement, more power, more torque, and revised engine technology across the board. For truck owners who still want a V8 under the hood, the Gen 6 small-block looks like a substantial step forward from the engines it replaces.