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Chevrolet’s 755-hp Gen-V LT5 is the most powerful small-block in the company’s engine timeline. That title needs a qualifier: the LT5 is supercharged, while the 505-hp LS7 holds Chevrolet’s separate distinction as the most powerful naturally aspirated small-block in GM history and the largest small-block factory-installed in a production vehicle.
Which GM small-block is the most powerful?
By Chevrolet’s published timeline, the answer is the Gen-V LT5: it powered the C7 Corvette to 755 hp, with a 2.65-liter Eaton supercharger. Chevrolet describes the LT5 as its most powerful small-block. The LS7 is a different record-holder, not a rival for that same unqualified horsepower title: its 505 hp came without forced induction, and Chevrolet calls it the most powerful naturally aspirated small-block in GM history.
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Those figures describe different approaches to output. The LS7 uses 7.0 liters of displacement to make naturally aspirated power; the LT5 makes more horsepower from a 6.2-liter engine with supercharging. Chevrolet’s claims are manufacturer specifications, not the results of an independent comparison test. Chevrolet’s small-block timeline and LS7 crate-engine guide provide the relevant distinctions.
How the LS7 and LT5 compare
| Engine | Generation and displacement | Induction | Published output | Distinction and application |
|---|---|---|---|---|
| LS7 | Gen IV, 7.0L (427 cu. in.) | Naturally aspirated | 505 hp | Chevrolet identifies it as the most powerful naturally aspirated small-block in GM history and the largest small-block factory-installed in a production vehicle; used in the 2007 Corvette Z06. |
| LT5 | Gen V, 6.2L (376 cu. in.) | 2.65L Eaton supercharger | 755 hp | Chevrolet’s most powerful small-block, used in the C7 Corvette. |
Specifications and distinctions are from Chevrolet’s engine timeline and LS7 materials and the LT5 installation sheet. The LT5 installation sheet specifies a 6,600-rpm maximum engine speed.
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Why the LT5 claimed the overall small-block horsepower record
The small-block’s long production life has involved successive generations and different engineering priorities. The family began with a 265-cubic-inch (4.3-liter) engine built at Flint on July 9, 1954, and introduced for the 1955 Corvette, where it made up to 195 hp. GM says Flint built more than 40 million small-blocks through 1999 and reports that it has produced more than 100 million small-block V8s overall.
Chevrolet’s timeline places the Gen-III LS1 in 1997 and LS6 in 2001, then the Gen-IV LS7 in 2005. The LS7’s 505 hp was a landmark for naturally aspirated small-block output. Chevrolet also lists the 2005 LS9, at 638 hp and 604 lb-ft, as a factory-installed small-block in the C6 Corvette ZR1. The later Gen-V LT5, listed for 2019, surpassed that figure with 755 hp by adding a large supercharger to a 6.2-liter package.
The contrast is the key to the title: the LS7 pursued high output through a larger naturally aspirated engine, while the LT5 used forced induction to set Chevrolet’s overall small-block horsepower mark. The LT5’s supercharger is a 2.65-liter Eaton unit, according to Chevrolet’s timeline.
What “factory-installed” means for the LS7
Chevrolet identifies the LS7 as the largest small-block factory-installed in a production vehicle. That wording matters: it refers to an engine fitted by the manufacturer in a production application, including the LS7-powered 2007 Corvette Z06. It should not be conflated with a crate engine sold separately for a project or custom build.
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Chevrolet also features an LS7-powered 1970 Chevelle in its Heritage Collection, but describes that car as re-powered. It is not evidence that the LS7 was factory-installed in a 1970 Chevelle.
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Why the ZZ632 does not take the small-block title
GM’s 2021 ZZ632/1000 makes 1,004 hp and 876 lb-ft, but it is a naturally aspirated 632-cubic-inch big-block crate engine—not a small-block and not a production-car installation. Its much higher horsepower therefore does not contradict Chevrolet’s LT5 claim. The engine’s classification and launch figures come from GM’s ZZ632 announcement.
What newer small-blocks mean for the record
GM’s September 2026 announcement described sixth-generation truck small-blocks: the 5.7-liter L76 and 6.6-liter L78. GM reported 481 hp and 501 lb-ft for the L78. Chevrolet separately reported a 6.7-liter LS6 for 2027 Corvette models, rated at 535 hp and 520 lb-ft with 13.0:1 compression. These announcements show the small-block family continuing into new applications, but neither overturns Chevrolet’s LT5 claim of 755 hp for its most powerful small-block.
GM says the sixth-generation engines retain the family’s 4.40-inch bore-center spacing. The new truck engines increase displacement over earlier 5.3- and 6.2-liter engines with a 6 mm longer stroke, and use higher compression, larger throttle diameters, tuned intake runners, dual direct/port injection, and a continuously variable oil pump. These are details of the newer truck-engine designs, not specifications for the LS7 or LT5. See GM’s September 2026 announcement and Chevrolet’s 2027 Corvette engine story.
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Can you buy an LS7 as a crate engine?
Chevrolet offers LS7 crate-engine materials for builders, but a crate engine is a standalone package, not a plug-in replacement guaranteed to fit every vehicle. Confirm the exact configuration, supporting parts, installation requirements and vehicle compatibility before planning a build. Chevrolet also warns that some emissions-related parts are intended for competition use and may not comply with road-vehicle emissions laws. Consult the applicable Chevrolet LS7 guide and Chevrolet Performance catalog for product-specific information.
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