page_title: General Motors LS-based small-block engine
section_title: Generation III (1997–2007)
hierarchical_section_title: General Motors LS-based small-block engine / Generation III (1997–2007)
context_page_description: The LS based small-block engine is the primary V8 used in General Motors' line of rear-wheel-drive cars and trucks. Introduced in January 1995, it is a "clean sheet" design with only rod bearings, lifters, and bore spacing in common with the longstanding Chevrolet small block V8 that preceded it as the basis for GM small-block V8s. The basic LS variations use cast iron blocks, while performance editions are all aluminium with cast iron cylinder liners.
  The LS small-block has been manufactured in three Generations – III, IV, and V – with preceding Generations I and II of modular GM small-block engines having been based on the Chevrolet small-block V8 originally released in 1954. GM recycled the "LT" designation beginning with the LS Generation V "LT1" in 2014.
  Several versions of the LS were used in the Chevrolet Corvette, beginning with the LS1 in 1997 through the LS9 and others in 2013. Variants of the LT version of the GM small-block have been used since.
  Most of the credit for this engine family must go to Ed Koerner, GM's Powertrain vice president of engineering operations at the time.
context_section_description: The GM Generation I and Generation II (LT) engine families are both derived from the longstanding Chevrolet small block V8. The Generation III small-block V8 was a "clean sheet" design, which replaced the Gen I and Gen II engine families in 2002 and 1995 respectively.
  Like the previous two generations, the Buick and Oldsmobile small blocks, the gen III/IV can be found in many different brands. The engine blocks were cast in aluminium for car applications, and iron for most truck applications (notable exceptions include the Chevrolet TrailBlazer SS, Chevrolet SSR and a limited run of Chevrolet/GMC Extended Cab Standard Box Trucks).
  The architecture of the LS series makes for an extremely strong engine block with the aluminium engines being nearly as strong as the iron generation I and II engines. The LS engine also used coil-near-plug style ignition to replace the distributor setup of all previous small-block based engines.
  The traditional five-bolt pentagonal cylinder head pattern was replaced with a square four-bolt design (much like the 64-90 Oldsmobile V8), and the pistons are of the flat-topped variety (in the LS1, LS2, LS3, LS6, LS7, LQ9 and L33), while all other variants, including the new LS9 and LQ4 truck engine received a dished version of the GM hypereutectic piston.
  The cylinder firing order was changed to 1-8-7-2-6-5-4-3, so that the LS series now corresponds to the firing pattern of other modern V8 engines (for example the Ford Modular V8).
caption: GM LS1 engine in a Chevrolet Corvette C5
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