GM LS engine
From Wikipedia, the free encyclopedia
The LS is Generation III and Generation IV, the latest evolution of General Motors' line of small-block V8 engines. The LS series was a clean sheet design, drawing on the heritage of the classic small-block, but is all-aluminum and has 6-bolt main bearing caps. The LS engine has been the sole powerplant of Chevrolet Corvette since 1997, and has seen use in a wide variety of other General Motors vehicles ranging from pony cars to full size trucks.
Contents |
[edit] Generation III
The Generation III small-blocks replaced the LT family in 1997. These shared the same rough displacement and bore spacing (4.4") as their cast iron predecessors but almost everything else was changed. The bore was reduced to 3.9 in and the stroke longer at 3.62 in for greater low end torque. The engine blocks were cast in aluminum for car applications, and iron for most truck applications (notable exceptions include the Chevrolet TrailBlazer). The engine also introduced coil-on-plug ignition to the small-block V8. The traditional five-bolt pentagonal cylinder head pattern was replaced with a square four-bolt design, and the pistons are of the flat-topped variety. The cylinder firing order was changed to 1-8-7-2-6-5-4-3, so that the LS series now corresponds firing pattern of other modern V8 engines.
[edit] LS1
The LS1 shares little other than similar displacement, external dimensions, and rod bearings, with the earlier small-block V8 engines. It is an all-aluminum 5.7 L (346 in³) pushrod engine and was rated between 305 - 350 hp (227 to 261 kW) and 335-365 ft·lbf (454-498 N·m) of torque in North America, depending on the application. In Australia, continuous modifications were made to the LS1 engine throughout its lifetime, reaching 382 hp (285 kW) in the HSV's YII series and a Callaway modified version, named C4B, was fitted to HSV GTS models producing 402 hp (300 kW). The version fitted to the Pontiac GTO featured a higher-lift camshaft to produce 350 hp (261 kW) and 365 ft·lbf (494 Nm) of torque. Beginning in 2001, the LS1 received the higher-flowing intake (from the LS6), and a smaller camshaft to keep power at the same level; this also allowed GM to remove the exhaust gas recirculation (EGR) system (Camaro/Firebird only; 97-00 Corvette LS1 never used an EGR system). The block is very similar to that of the higher-output LS6; beginning in 2002, some LS1 engines were actually built using the LS6 block instead. The LS1 was on the Ward's 10 Best Engines list for 1998.
Applications:
- 1997-2004 Chevrolet Corvette C5, excluding Z06
- 2001-2005 Chevrolet Corvette C5-R, powered by a 7.0 L variation of the LS1
- 1998-2002 Chevrolet Camaro Z28, SS
- 1998-2002 Pontiac Firebird Formula and Trans-Am
- 2004 Pontiac GTO
- 1999-2005 Holden Commodore (VT, VX, VY, VZ)
- 1999-2005 Holden Statesman (WH, WK, WL)
- 1999-2005 Holden Caprice (WH, WK, WL)
- 1999-2004 Holden Special Vehicles (all V8 models)
- 2001-2005 Holden Monaro CV8
- 2006-2007 Elfin MS8 Streamliner
[edit] LS6
- LS6 can also refer to a 454 in³ Chevrolet Big-Block engine of the 1970s
The LS6 is a higher-output version of Chevrolet's small-block LS1 engine. It is an all-aluminum 5.7 L (346 in³) pushrod engine. The initial 2001 LS6 produced 385 hp (287 kW) and 385 ft·lbf (522 N·m), but the engine was modified for 2002 through 2004 to produce 405 hp (302 kW) and 400 ft·lbf (542 N·m) of torque. The LS6 was originally only used in the high-performance C5 Corvette Z06 model, with the Cadillac CTS V-Series getting the 405 hp engine later. The V-Series used the LS6 for two years; it was replaced with the LS2 in 2006. For 2006, the Z06 replaced the LS6 with the new 7.0L LS7.
The LS6 shares its basic block design with the GM LS1 engine, but other changes were made such as windows cast into the block between cylinders. An improved intake manifold, higher-lift cam, and higher compression ratio boost output compared to the LS1, and a new oiling system is better suited to high lateral acceleration.
The casting number, located on the top rear edge of the block, is 12561168.
[edit] Generation IV
In 2004, the Generation III was superseded by the Generation IV. These big-bore engines are some of the largest small-blocks yet, and were quickly phased in to replace the previous generation. Displacement ranges up to 7.0 L and output to 505 hp (373 kW). Building upon the Generation III design, Generation IV was designed with displacement on demand in mind, a technology that allows one bank of cylinders to be deactivated. It can also accommodate variable valve timing. A 3-valve per cylinder design was originally slated for the LS7, which would have been a first for a pushrod engine; but the idea was shelved owing to design complexities and when the same two-valve configuration as the other Generation III and IV engines proved to be sufficient to meet the goals for the LS7.
[edit] L76
- See also the Vortec 6000 L76
L76 was originally Holden's version of the 6.0 L Generation IV engine. While early models lacked the displacement on demand technology found on some versions, this feature is enabled on the 2008 Pontiac G8. The engine also meets Euro III emissions requirements. Output is 348 hp (260 kW) at 5600 rpm and 376 ft·lbf (510 N·m) at 4400 rpm for the Holden variant, and 362 hp (270 kW) and 391 ft·lbf of torque (530 N·m) for the version to be used in the G8.[1]
Applications:
- 2006-present Holden VZ Commodore
Future Applications:
- 2008 Pontiac G8
[edit] L98
- For the tuned-port Generation I engine of the same RPO, see Chevrolet L98
The L98 is a slightly modified version of the L76, devoid of some redundant hardware relating to displacement on demand. Power increased to 362 hp (270 kW) at 5700 rpm and 391 ft·lbf (530 Nm) at 4400 rpm.
Applications:
- 2006-2007 Holden VE Commodore
- 2006-2007 Holden WM Statesman / Holden WM Caprice
[edit] LS2
The LS2 was introduced as the Corvette's new base engine for the 2005 model year. It produces 400 hp (298 kW) at 6000 rpm and 400 ft·lbf (542 N·m) at 4400 rpm from a slightly larger displacement of 6.0 L (364.3 in³). It is similar to the high-performance LS6, but with an improved power peak and more torque throughout the rpm range. The E-series HSV's are equipped with a 412 hp (307 kW) and 406 ft·lbf (550 Nm) version.
Applications:
- 2005-2007 C6 Chevrolet Corvette
- 2005-2006 Pontiac GTO
- 2005-2006 Chevrolet SSR
- 2006-2007 Chevrolet TrailBlazer SS
- 2006-2007 Cadillac CTS-V
- 2004-2007 Holden Special Vehicles (all V8 models)
- 2005-2006 Vauxhall Monaro VXR
[edit] LS4
The LS4 is a smaller 5.3 L (325 in³) version of the Generation IV block. Though it has the same displacement as the Vortec 5300 LH6, it differs in that it has an aluminum block rather than an iron one and it uses the same cylinder head as the Generation III LS6 engine.
A version of this engine is adapted for transverse front-wheel drive application. In order to fit into the smaller engine compartments designed for V-6s, in the front-wheel drive Pontiac Grand Prix GXP, for instance, the LS4 engine block had to be shortened by one inch. Displacement on Demand is also used. Output of this version is 303 hp (226 kW) and 323 ft·lbf (438 N·m).
Applications:
- 2006-2007 Chevrolet Impala/Monte Carlo SS
- 2005-2008 Pontiac Grand Prix GXP
[edit] LS7
The LS7 is the latest high-power LS engine. It is a 7.0 L (427.6 in³) unit, based on the Gen IV architecture. The block is changed, with a larger 4.125 in (104.9 mm) bore and longer 4.00 in (101.6 mm) stroke than the LS2. The small-block's 4.4 in (111.8 mm) bore spacing is retained, requiring pressed-in cylinder liners. The crankshaft and main bearing caps are forged steel for durability, the connecting rods are forged titanium, and the pistons are hypereutectic, possibly to keep the relatively small mass pistons in check when they thermally expand at operating temperature. The two-valve arrangement is retained, though the titanium intake valves by Del West have grown to 2.20 in (55.9 mm) and sodium-filled exhaust valves are up to 1.61 in (40.9 mm). The LS7 is also the only current Gen IV engine to feature dry sump lubrication.
Peak output is 505 hp (377 kW) at 6300 rpm and 470 ft·lbf (637 N·m) at 4800 rpm with a 7000 rpm redline. During GM's reliability testing of this engine in its prototype phase, the LS7 was remarked to have been repeatedly tested to be 8000 rpm capable, although power was not made at that rpm level, due to the restraints of the camshaft's profile and the intake manifold ability to flow required air at that engine speed.
The LS7 is hand-built by the General Motors Performance Build Center in Wixom, Michigan. Most of these engines are installed in the Z06, but some are also sold to individuals by GM as a crate engine. No other vehicles are currently confirmed to use the LS7 in the future.
The 7.0 L mark had already been reached by the LS-series of racing engines, famously in the 24 Hours of Le Mans Corvette C5R. GMMG Berger Camaro ZL1s made late in 2002 and GMMG Berger Dick Harrell Camaros (inspired by the Roger Penske Mark Donahue concept car) also featured variations of the 7.0 L size.
Applications:
- 2006-2007 Chevrolet Corvette Z06
Chevrolet previously used the LS-7 designation (note the hyphen) to name a higher horsepoweer version of the 454 cubic inch (7.4 L) Mark IV engine in 1970. However given the anti-performance regulations looming in the near future, the LS-7 as a whole never left the drawing board. Essenstially the stillborne LS-7 was to have an improved intake manifold escalating output to 465HP (versus the famed LS-6's 450HP). However an unknown quantity of LS-7 intake manifolds were produced by the factory and sold by dealers as in-house performance options. The 1970 LS-7 was in no way related to the present day LS7—the two engines are completely different designs.
[edit] LS7.R
The LS7.R motor is a variation of the LS7 used in the highly successful C6.R American Le Mans Series racecar. It was crowned as Global Motorsport Engine of the Year by a jury of 50 race engine engineers on the Professional Motorsport World Expo 2006 in Cologne, Germany.
[edit] LSX
At the 2006 SEMA show, GM Performance Parts introduced the LSX engine, an all-new cast-iron racing block based on the LS7 engine. It was designed with help from drag racing legend Warren Johnson, and despite being based on GM's small-block design, it offers displacements ranging from 364 cubic inches to 511 cubic inches (4.25" Bore x 4.5" Stroke) and is capable of withstanding 2500 bhp. This block incorporates two extra rows of head-bolt holes per bank for increased clamping capacity. The six bolt steel main caps are the same ones used on the LS7 engine. The engine debuted at the auto show in a customized 1969 Camaro owned by Reggie Jackson. The LSX will be available starting the second quarter of 2007, set to be available in authorized dealerships and retailers on March 31, 2007.[2]
[edit] LS9
Early reports indicate that a 6.2 L LS9 derivative is due in 2008. Displacement was a reportedly decreased for a thicker cylinder wall, to promote a stronger cylinder to deal with the rigors of possibly forced induction. A picture of this motor was seen drifting around on the internet, and it seems to be equipped with a positive displacement supercharger and is stated to produce 650 hp (485 kW).
[edit] Vortec engines
- Versions of both the Generation III and Generation IV V8 have also been used in trucks and SUVs. These are usually branded as GM Vortec engines. For information on GM Vortec engines in Wikipedia, see GM Vortec engine.
[edit] Problems
In the early production run of the LS-series engine, some engines encountered abnormal amounts of 'piston slap' - a problem caused by too much clearance between the cylinder bore and the piston. [3] However, the scope of the problem appears to be fairly limited as no recall has been issued by General Motors, and the majority of owners of these engines do not report this issue.[citation needed] Additionally, it appears that this issue is confined only to a small number of the engines produced between 1997 and 2002.[citation needed]
'Piston Slap' should not be confused with a light ticking sound often produced by some of these engines that often goes away when the engine warms up. This is usually the sound of the lifters ticking. 'Piston Slap' sometimes sounds more like a nock or the sound of a diesel engine running. The noise of 'Piston Slap' often is louder when listening for it below the oil pan.
[edit] See also
- GM Small-Block engine - Generation I
- GM LT engine - Generation II
- Chevrolet Corvette
