The 5.7L LS6 is the most powerful Gen. 3 small block engine as it came from the factory. It is an improved version of the LS1 produced for the 2001 Z06 Corvette.

The LS6 powered the 2001-04 Corvette Z06 and the 2004-05 Cadillac CTS-V.

Mechanically similar, General Motors’ LS and LS-based Vortec engines wound up on almost every branch of the GM family tree: Chevy, Pontiac, GMC, Cadillac, Buick—heck, even Saab, Hummer, and Isuzu got some LS love.

Since LS and Vortec engines are so common, they’ve become the go-to performance and swap engines of the modern era.

These motors are capable of making a lot of horsepower, and respond well to upgrades like turbos, superchargers, high-flow cylinder heads, intake systems, cams, and nitrous oxide.

The aftermarket is strong, crate engines are available, and used motors are often cheaply sourced through junkyards.

Summit Racing has created a series of comprehensive guides for each engine in the LS family, so engine builders and tuners can have a handy reference for their projects.

This specific guide is for the GM LS6 engine.

[Looking to upgrade your LS6 engine? Check out LS6 Engine Upgrade Guide: Expert Advice for LS6 Mods to Maximize Performance.]

You can see all of our LS engine spec guides and LS-related information here.

(Summit Racing’s Brian Nutter and Paul Spurlock contributed to this article.)

Chevy LS6 Engine Specs

LS6 Performance Specifications

Engine Ratings
Compression Ratio10.5:1
Horsepower Rating385-405 hp
Torque Rating385-400 ft./lbs.

LS6 Applications

VIN 8th DigitYearMakeModel
S2001-04ChevyCorvette Z06

LS6 Engine Blocks

LS6 Block Specs
Casting Number12561168
MaterialAluminum - Sand Cast
Displacement5.7L / 346 cid
Bore Dia. 3.898 in.
Stroke3.622 in.
Deck Height9.240 in.
Bore Spacing4.400 in.
Thrust Bearing Location#3 Main
Main Cap Style6-Bolt
Main Housing Bore Dia.2.751 in.
Cam Housing Bore Dia. (2002-03)Bore 1/5 = 2.326, Bore 2/4 = 2.317, Bore 3 = 2.307
Cam Housing Bore Dia. (2003-04)Bore 1/5 = 2.346, Bore 2/4 = 2.326, Bore 3 = 2.307
Cam-to-Crank Centerline4.914 in.

LS6 Rotating Assembly

LS6 Rotating Assembly Specs
Piston MaterialHypereutectic Cast Aluminum Alloy M142
Piston StyleFlat Top
Piston Volume0cc
Wrist Pin Dia.
(2001-late 2004)
0.9449 in (Press Fit)
Wrist Pin Dia.
(Late 2004-05)
0.9435 in (Full Floating)
Connecting Rod MaterialPowdered Metal
Connecting Rod StyleI-Beam
Connecting Rod Length6.098 in.
Connecting Rod BoltsM9 x 1 x 43
Crankshaft MaterialCast Iron
Crankshaft Main Journal2.559 in.
Crankshaft Rod Journal2.100 in.
Reluctor Wheel24X
Flywheel Mounting Flange0.857 in.

LS6 Cylinder Heads

LS6 Cylinder Head Specs
2001-04 Casting Numbers12564243
Combustion Chamber Volume65cc
Intake Port ShapeCathedral
Intake Runner Volume210cc
Exhaust Port ShapeD-Port
Exhaust Runner Volume75cc
Intake Valve Diameter2.000 in.
Exhaust Valve Diameter1.550 in.
Cylinder Head Bolt StyleTorque to Yield (TTY)
Cylinder Head Bolt Size 1997-2003(8) M11 x 2 x 155, (2) M11 x 2 x 100, (5) M8 x 1.25 x 45
Cylinder Head Bolt Size 2004(10) M11 x 2 x 100, (5) M8 x 1.25 x 45

LS6 Cam Specifications

Duration @.050
Duration @.050
Int. LiftExh. LiftLobe Separation
2001Corvette Z06204°211°0.525"0.525"116°
2002-04Corvette Z06204°218°0.555"0.551"117.5°

LS6 Valvetrain

LS6 Valvetrain Specs
Lifter StyleHydraulic Roller
Lifter Link StylePlastic Lifter Tray
Lifter Body Diameter0.842 in.
Pushrod Length7.385 in.
Rocker Arm Mounting StylePedestal
Rocker Arm StyleDie-Cast, Roller Fulcrum
Rocker Ratio1.7
Rocker OffsetNone
Valve Spring StyleBeehive
Valve Spring ColorBlue (2001), Yellow (2002-04)
Valve Spring PressureYellow = 90 lbs. Seat / 260 lbs. Open
Valve Angle15 Degrees
Intake Valve MaterialSteel - Solid Stem
Intake Valve Dia.2.000 in.
Exhaust Valve MaterialSteel - Sodium Filled Stem
Exhaust Valve Dia.1.550 in.

Other Key LS6 Specs

Throttle Body, Fuel Injectors, Oil Pan Specs & More
Intake ManifoldLS6
Throttle Body78mm, 3-Bolt
Throttle ControlElectronic, Drive-by-Wire
Fuel Injector Flow30 lbs./hr.
Fuel Injector Length (between O-Rings)2.5 in.
Fuel Injector ConnectorEV1
Crankshaft Reluctor Ring24x
Camshaft SensorRear Mount, 1x on Cam
Oil Pan
Bat Wing, Rear Sump
Oil Pan
Rear Sump
Oil PumpStandard Volume

NOTE: You can find engine specs and detailed engine upgrade advice for every LS and LS-based Vortec truck engine in one place: The Definitive Guide to LS Engine Specs and LS Engine Upgrades.

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