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Top > Engine Components > Gen III, LS1 - LS6 - LS7 - LSX > The LS Family Tree |
Untitled Document
The
LS Engine Family Tree
Everything you wanted to know about GM’s 21st-century Small-Block,
but were afraid to ask!
Gen III / IV Small-Block crate engines
LS heritage
The engine family commonly called the LS Series debuted in 1997. General
Motors called it the Gen III Small-Block, with the iron-block versions in trucks
and the all-aluminum LS1 version introduced in the then-new C5 Corvette. A
year later, the LS1 replaced the LT1 Small-Block in Camaros and Firebirds. The
LS1 displaced 5.7 liters, similar to the previous-generation Small-Block, but
the
cubic-inch measurement differed slightly: 346 for the LS1 versus the traditional
350 cubes.
In 1999, the Gen III platform spawned the higher-performance LS6 that was
standard in the Corvette Z06. In 2005, the Gen IV branch of the LS family was
born, differing from the Gen III with cast-in provisions for fuel-saving cylinder
deactivation,
larger displacements and revised camshaft sensing. The performance
versions of the Gen IV include the LS2, LS3, LS7 and LS9 supercharged.
GM has continued to refer to its modern V-8 engine family as Gen III and Gen
IV, but to the enthusiasts who quickly grasped the tremendous performance
potential of the engines, every engine based on the platform is nicknamed “LS.”
The range of production engines from the LS platform is wide. On the truck side,
iron-block engines have included 4.8L and 5.3L versions, as well as all-aluminum
6.0L and 6.2L premium engines. Car engines include 5.3L, 5.7L, 6.0L, 6.2L and
7.0L displacements–including some configured for front-wheel-drive.
Gen II versus Gen IV
Despite some significant differences between Gen III and Gen IV cylinder
blocks, all LS engines share common traits that include:
• 4.40" bore centers (like the original Small-Block)
• Six-bolt, cross-bolted main bearing caps
• Center main thrust bearing
• 9.24" deck height
• Four-bolt-per-cylinder head bolt pattern
• 0.842" lifter bores
• Distributorless, coil-near-plug ignition system
The most distinguishing differences between Gen II and Gen IV cylinder
blocks are larger bores (on some engines), different camshaft position sensor
locations—front timing cover area on Gen IV blocks and top-rear position
on Gen
III blocks—and, on most Gen IV blocks, cast-in provisions for GM’s
Active Fuel
Management cylinder deactivation system.
There is great interchangeability between all LS engines (including between
Gen III and Gen IV versions). Cylinder heads, crankshafts, intake manifolds and
more can be mixed and matched—but the devil is in the details. Not every
head matches every intake manifold and not every crankshaft works with every
engine combination. Will Handzel’s “How to Build High-Performance
Chevy
LS1/LS6 V-8s”P/N 88958786 is a great reference source that outlines the
more
specific differences and interchangeability among Gen III-based engines.
LS4
Perhaps the most unique application of the LS engine in a car, the LS4 is a 5.3L
version used in the front-wheel-drive Chevrolet Impala SS and Pontiac Grand Prix
GXP. The LS4 has an aluminum block and unique low-profile front-end accessory
system, including a “flattened” water pump to accommodate the transverse
mounting position within the Impala and Grand Prix. It is rated at 303 horsepower
and 323 lb-ft of torque.
LS1/LS6
LS1 5.7L (346-cu-in) engines were produced between the 1997 and 2004 model
years in the United States (Corvette, Camaro, Firebird and GTO) and stretching
into 2005 in other markets (primarily Australia). The LS6 was introduced in 2001
in the Corvette Z06 and was manufactured through 2005, when it also was
found in the Cadillac CTS-V. The LS1 and LS6 share a 5.7L displacement, but
the LS6 production engine uses a unique block casting with enhanced strength,
greater bay-to-bay breathing capability and other minor differences. The heads,
intake manifolds and camshaft also are unique LS6 parts.
LS2
In 2005, the LS2 6.0L (364 cubic inches) engine and the Gen IV design changes
debuted. In GM performance vehicles, it was offered in the Corvette, GTO and
even the heritage-styled SSR roadster. Its larger displacement brought greater
power. The LS2 is one of the most adaptable engines, as LS1, LS6, LS3 and L92
cylinder heads work well on it.
LS3/L99
Introduced on the 2008 Corvette, the LS3 brought LS base performance to an
unprecedented level: 430 horsepower from 6.2L (376 cubic-inches)—making
it
the most powerful base Corvette engine in history. The LS3 block not only has
larger bores than the LS2, but a strengthened casting to support more powerful
6.2L engines. The LS3 is offered in the Pontiac G8 GXP and is also the standard
V-8 engine in the new, 2010 Camaro SS. The L99 version is equipped with GM’s
fuel-saving Active Fuel Management cylinder deactivation system and is standard
on 2010 Camaro SS models equipped with an automatic transmission.
LSA
The baby brother to the LS9, this supercharged 6.2L engine is standard in the
2009 Cadillac CTS-V. It is built with several differences when compared to the
LS9, including hypereutectic pistons versus the LS9’s forged pistons and
a
smaller, 1.9L supercharger. The LSA also has a different charge-cooler design
on
top of the supercharger. Horsepower is rated at 556 in the super-quick Caddy.
LS9
The most powerful production engine ever from GM, the LS9 is the 6.2L supercharged
and charge-cooled engine of the Corvette ZR1. It is rated at an astonishing
638 horsepower. The LS9 uses the strengthened 6.2L block with stronger,
roto-cast cylinder heads and a sixth-generation 2.3L Roots-type supercharger.
Like the LS7, it uses a dry-sump oiling system. It is the ultimate production
LS
engine. It is built by hand at the GM Performance Build Center in Wixom, Mich.
LS7
A legend in its own time. The LS7 is the standard engine in the Corvette Z06
and its 7.0L displacement (427 cubic inches) makes it the largest small block
engine offered in a production car. Unlike LS1/LS6, LS2 and LS3 engines, the
LS7 uses a siamese-bore cylinder block design—required for its big, 4.125-inch
bores. Competition-proven heads and lightweight components, such as titanium
rods and intake valves, make the LS7 a street-tuned racing engine, with 505
horsepower. LS7 engines are built by hand at the GM Performance Build Center
in Wixom, Mich.
Gen II and Gen IV Vortec truck engines
Although performance car engines have typically carried “LS” designations,
truck engines built on this platform have been dubbed Vortec. They are generally
distinguished by iron cylinder blocks and smaller displacements than car
engines. Interestingly, a 5.7L Vortec “LS” engine has never been offered.
Here’s
a quick rundown of the previous and current-production LS truck engines:
• 4.8L—The smallest-displacement LS engine (293 cubic-inches);
it uses
an iron block with 3.78-inch bores and aluminum heads.
• 5.3L—The most common LS truck engine, it uses the
same iron block
with 3.78-inch bores as the 4.8L, but with a larger, 3.62-inch stroke
crankshaft (327 cubic inches). Later versions are equipped for Active
Fuel Management. Manufactured with iron and aluminum cylinder
blocks.
• 6.0L—Used primarily in ¾-ton and one-ton
trucks, the 6.0L (364 cubicinches)
uses an iron block (LY6) or aluminum block (L76) and aluminum
heads, with provisions for Active Fuel Management; some equipped
with variable valve timing.
• 6.2L—Commonly referred to by its L92 engine code,
the 6.2L (376
cubic-inches) engine uses an aluminum block and heads, and incorporates
advanced technology including variable valve timing. The L92 is
used primarily as a high-performance engine for the Cadillac Escalade
and GMC Yukon Denali.
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