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

LQ4 Applications

LQ4 Engine Blocks

LQ4 Rotating Assembly

LQ4 Cylinder Heads

LQ4 Cylinder Head Specs
Years1999-20002001-07
Casting Numbers373, 873317, 035
MaterialIronAluminum
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

LQ4 Valvetrain Specs

Other Key LQ4 Specs

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.