LQ4 engine, GM 6.0LS

The LQ4 is a 6.0L LS (Gen. 3) small block engine used in GM trucks between 1999 and 2007. For marketing purposes, it was also known as the Vortec 6000. The engine specs and information listed here is for the stock LQ4 engine.

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 guide is specifically for the GM LQ4 engine.

[Looking to upgrade your LQ4 engine? Check out LQ4/LQ9 Engine Upgrade Guide: Expert Advice for LQ4 & LQ9 Mods to Maximize Performance.]

You can explore all of our LS engine spec guides and LS tech resources here.

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

Chevy LQ4 Engine Specs

LQ4 Performance Specifications

Engine Ratings
Compression Ratio9.4:1
Horsepower Rating300-330 hp
Torque Rating360-370 ft./lbs.

LQ4 Applications

VIN 8th DigitYearMakeModel
U1999-04ChevySilverado 2500
U2001-07ChevySilverado 1500 HD
U2001-07ChevySilverado 2500 HD
U2001-07ChevySilverado 3500
U2002-04GMCSierra 1500 Denali
U2001-06GMCSierra 1500 HD (+2007 Classic)
U1999-04GMCSierra 2500
U2001-06GMCSierra 2500 HD (+2007 Classic)
U2001-06GMCSierra 3500 HD (+2007 Classic)
U2001-06GMCYukon Denali, XL1500, XL2500

LQ4 Engine Blocks

LQ4 Block Specs
Casting Numbers12551364, 12573581, 12577184
Displacement6.0L / 364 c.i.d.
Bore Dia. 4.000 in.
Stroke3.622 in.
Deck Height9.230 - 9.240 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. (1999-2003)Bore 1/5 = 2.326, Bore 2/4 = 2.317, Bore 3 = 2.307
Cam Housing Bore Dia. (2003-07)Bore 1/5 = 2.346, Bore 2/4 = 2.326, Bore 3 = 2.307
Cam-to-Crank Centerline4.914 in.

LQ4 Rotating Assembly

LQ4 Rotating Assembly Specs
Piston MaterialHypereutectic Cast Aluminum Alloy
Piston StyleDished
Piston Volume+ 6.7cc
Wrist Pin Dia.
0.9447 in., 0.9448 in.
(Press Fit)
Wrist Pin Dia.
0.9429 in., 0.9431 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
Flexplate/Flywheel Mounting Flange (1999-2000)1.250 in.
Flexplate/Flywheel Mounting Flange (2001-07)0.857 in.

LQ4 Cylinder Heads

LQ4 Cylinder Head Specs
Casting Numbers373, 873317, 035
Combustion Chamber Volume71cc71cc
Intake Port ShapeCathedralCathedral
Intake Runner Volume200cc210cc
Exhaust Port ShapeOvalD-Port
Exhaust Runner Volume70cc75cc
Intake Valve Diameter2.000 in.2.000 in.
Exhaust Valve Diameter1.550 in.1.550 in.
Cylinder Head Bolt StyleTorque to Yield (TTY)Torque to Yield (TTY)
Cylinder Head Bolt Size 1999-2003(8) M11 x 2 x 155, (2) M11 x 2 x 100, (5) M8 x 1.25 x 45
Cylinder Head Bolt Size 2004-07(10) M11 x 2 x 100, (5) M8 x 1.25 x 45

LQ4 Cam Specifications

Duration @ .050 in. (int./exh.)191/190196/207
Valve Lift (int./exh.)0.457 in./0.466 in.0.467 in./0.479 in.
Lobe Separation Angle114°116°
Cam Gear Attachment3-Bolt3-Bolt

LQ4 Valvetrain Specs

LQ4 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 ColorNatural
Valve Angle15 Degrees
Intake Valve MaterialSteel - Solid Stem
Intake Valve Dia.2.000 in.
Exhaust Valve MaterialSteel - Solid Stem
Exhaust Valve Dia.1.550 in.

Other Key LQ4 Specs

Throttle Body, Fuel Injectors, Oil Pan Specs & More
Intake ManifoldTruck Style
Throttle Body80mm, 3-Bolt
Throttle Control (1999-02)Cable-Operated
Throttle Control (2003-04)Electronic, Drive-by-Wire (for most models)
Fuel Injector Flow24.8 lbs./hr.
Fuel Injector Length (between O-Rings)1.9 in.
Fuel Injector ConnectorEV6
Crankshaft Reluctor Ring24x
Camshaft SensorRear Mount, 1x on Cam
Oil Pan
Deep 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.