LS3 Engine Specs, Horsepower & LS3 vs LS2, L99

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October 4, 2026
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LS3 Engine: Specs, Horsepower and LS3 Crate Engines

The LS3 is GM’s 6.2-liter (376 cubic inch) aluminum V8 from the Gen IV LS family, introduced in the 2008 Chevrolet Corvette at 430 HP. It combines a 4.065″ bore and 3.622″ stroke with high-flow rectangular-port cylinder heads and 10.7:1 compression. Strong power, light weight and wide parts support have made it one of the most popular engines for swaps and new crate engines.

LS3 engine specs

Specification	LS3
Displacement	6.2L (376 cubic inches)
Family	GM Gen IV small block (LS)
Bore x stroke	4.065″ x 3.622″
Block	Aluminum with cast-iron cylinder liners, 6-bolt main caps
Cylinder heads	Aluminum, rectangular intake ports (L92-style)
Compression ratio	10.7:1
Camshaft	Hydraulic roller, pushrod valvetrain
Fuel system	Port fuel injection
Firing order	1-8-7-2-6-5-4-3
Factory rating	430 HP (Corvette); 426 HP (Camaro SS with manual transmission)

The LS3 crate engines we list use the same recipe: a 376 cubic inch aluminum block, 3.622″ stroke nodular iron crankshaft, hypereutectic pistons, 68cc rectangular-port heads and 10.7:1 compression. For the full LS family, see GM LS engines explained.

How much horsepower does an LS3 make?

GM rated the LS3 at 430 HP in the C6 Corvette and 426 HP in the 2010 to 2015 Camaro SS with a manual transmission. The new GM Performance LS3 crate engines are rated at:

GM Performance LS3 430 HP (part 19434636): 430 HP and 425 lb-ft, with the intake manifold included.
GM Performance LS3 495 HP (part 19434638): 495 HP and 473 lb-ft from the more aggressive LS Hot Cam.
GM Performance LS3 495 HP long block (part 19434646): the Hot Cam engine without the intake, fuel rail and injectors, for builders who supply their own top end.
GM Performance CT525 (part 19434598): an LS3-based sealed circle-track engine rated at 533 HP and 477 lb-ft, with a carbureted intake and forged pistons.

LS3 vs LS2

The LS2 is the 6.0L (364 cubic inch) engine that preceded the LS3 in the 2005 to 2007 Corvette, where it was rated at 400 HP. The LS3 has a larger 4.065″ bore (against the LS2’s 4.000″), the same 3.622″ stroke, and rectangular-port heads that flow more air than the LS2’s cathedral-port heads. Rectangular-port heads need a matching rectangular-port intake manifold, so plan heads and intake together when you mix LS parts. For the LS2 and the other 6.0L engines, see our 6.0 LS engine guide.

LS3 vs L99 and L92

L99: the 6.2L used in automatic-transmission 2010 to 2015 Camaro SS models, rated at 400 HP. It adds variable valve timing and Active Fuel Management (cylinder deactivation) and has lower compression, about 10.4:1. Swappers often convert it to LS3 specification.
L92: GM’s 6.2L truck and SUV engine introduced for 2007, which first used the rectangular-port heads that the LS3 shares. It has variable valve timing.

LS3 vs LS1 and LT1

	LS1	LS3	LT1 (Gen V)
Displacement	5.7L (346 ci)	6.2L (376 ci)	6.2L (376 ci)
Bore x stroke	3.898″ x 3.622″	4.065″ x 3.622″	4.065″ x 3.622″
Heads	Cathedral port	Rectangular port	Gen V, direct injection
Fuel injection	Port	Port	Direct
Typical factory rating	305 to 350 HP	426 to 430 HP	455 HP (Corvette, Camaro SS)

The LT1 shares the LS3’s bore and stroke but is a different engine: direct injection, a different block and heads, and few interchangeable parts. For swaps, the LS3 is usually simpler to wire and fuel. If you want a modern Gen V engine, the supercharged LT4 crate engine is rated at 650 HP. Our LT4 engine guide compares the two.

Other engines built around LS3 parts

GM Performance 6.0L LS (LS364/450): a 452 HP long block with an iron block, LS3 rectangular-port heads and an LS6 camshaft. It needs an LS3/L92-style rectangular-port intake.
GM Performance LSX 376-B15: an LSX iron block with LSX-LS3 heads and forged internals, built to handle 15 psi of boost, rated at 473 HP.
BluePrint LS 376: a new GM 6.2L aluminum block engine rated at 520 HP and 470 lb-ft as a carbureted long block, and at 530 HP and 495 lb-ft in the EFI deluxe dressed version.
For a custom build, the GM Performance 6.2L LSA aluminum block shares the LS3’s 4.065″ bore.

See every option in LS and LT crate engines, and current prices in our crate engine price guide.

Swapping an LS3

An LS3 swap needs the same supporting parts as any LS swap: engine mounts, an oil pan that clears your chassis, an EFI fuel system, engine management and an accessory drive that fits. Check whether a crate engine includes a controller before you order, since many do not. See our LS swap guide and LS accessory drive kits.

Frequently asked questions

Is the LS3 a 6.2?

Yes. The LS3 displaces 6.2 liters, or 376 cubic inches, from a 4.065″ bore and 3.622″ stroke.

How much horsepower does an LS3 have?

GM rated the production LS3 at 430 HP in the Corvette and 426 HP in the Camaro SS. The GM Performance LS3 crate engines here are rated at 430 HP and 495 HP, and the LS3-based CT525 at 533 HP.

What is the compression ratio of an LS3?

10.7:1, which is also the rating on the LS3 and CT525 crate engines we list.

What is the difference between an LS3 and an L99?

Both are 6.2L Gen IV engines. The L99 adds variable valve timing and Active Fuel Management, has lower compression and was rated at 400 HP in the automatic Camaro SS, against 426 HP for the manual-transmission LS3.

Is the LS3 better than the LS2?

The LS3 makes more power from its larger bore and better-flowing rectangular-port heads, which is why it replaced the LS2. A good LS2 is still a capable, cheaper swap engine.

What cars came with the LS3 engine?

GM used the LS3 in the 2008 to 2013 Chevrolet Corvette, the 2010 to 2015 Camaro SS with a manual transmission (automatic SS models used the similar L99), the 2009 Pontiac G8 GXP and the 2014 to 2017 Chevrolet SS sedan. It is also sold new as a GM Performance crate engine.