LS Engines

LQ9 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More

twin-turbo LQ9

This LQ9 was swapped into a 1966 Buick Gran Sport and outfitted with twin turbos. (Image/thepicta.com)

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 LQ9 engine.

[Looking to upgrade your LQ9 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 LQ9 Engine Specs

The LQ9 is a Gen. 3 small block engine used in GM trucks between 2002 and 2007. For marketing purposes, it was also known as the Vortec HO 6000 or VortecMAX. The information listed here is for the stock engine.

LQ9 Performance Specifications

Engine Ratings
Compression Ratio10.1:1
Horsepower Rating345 hp
Torque Rating380 ft./lbs.

LQ9 Applications

VIN 8th DigitYearMakeModel
N2002-06CadillacEscalade
N2002-06CadillacEscalade EXT
N2002-06CadillacEscalade ESV
N2003-07ChevySilverado SS
N2004-06ChevySilverado HO Edition
N2004-06GMCSierra HO Edition
N2006-07ChevySilverado Classic VortecMAX
N2006-07GMCSierra 1500 Classic VortecMAX

LQ9 Engine Blocks

LQ9 Block Specs
Casting Numbers12551364, 12573581, 12577184
MaterialIron
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. (2002-03)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.

LQ9 Rotating Assembly

LQ9 Rotating Assembly Specs
Piston MaterialHypereutectic Cast Aluminum Alloy
Piston StyleFlat Top
Piston Volume0cc
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 Flange0.857 in.

LQ9 Cylinder Heads

LQ9 Cylinder Head Specs
Casting Numbers035, 317
MaterialAluminum
Combustion Chamber Volume71cc
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 2002-03(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

LQ9 Cam Specifications

LQ9 Cam Specs
Part Number12561721
Duration @ .050 in. (int./exh.)196/201
Valve Lift (int./exh.)0.467 in./0.479 in.
Lobe Separation Angle116°
Cam Gear Attachment3-Bolt

LQ9 Valvetrain Specs

LQ9 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 LQ9 Specs

LQ9 Throttle Body, Fuel Injectors, Oil Pan Specs & More
Intake ManifoldTruck Style
Throttle Body80mm, 3-Bolt
Throttle ControlElectronic, Drive-by-Wire
Fuel Injector Flow25.2 lbs./hr.
Fuel Injector Length (between O-Rings)1.9 in.
Fuel Injector ConnectorEV6
PCMWarren
Crankshaft Reluctor Ring24x
Camshaft SensorRear Mount, 1x on Cam
Oil Pan
Deep Rear Sump
Oil PumpStandard Volume
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7 Comments

  1. Pingback: LS Engines 101: An Introductory Overview of the Gen III/IV LS Engine Family - OnAllCylinders

  2. Larry Childers says:

    I’m putting a 2005 lq9 together, and the wrist pins are discolored. It looks like they got extremely hot? Any input? The bearings, all looked good. And blocked chk”d out good.

    • The LQ9s had full floating rods so there should have been less friction than the press-fit.
      The factories do run pin-to-piston clearance tight, in an effort to reduce noise. They will often have a .0002 in. press fit that opens up under running conditions when the aluminum pin bore expands more than the steel pin.
      Check the pin bores and see if there is any sign of metal transfer–this will appear as a tear in an otherwise smooth surface. You can also check the small end rod bushing.
      Check for excessive wear–you should be able to slide the pin in when it’s completely square and you should feel *almost* no vertical movement at the ends of the pin when you push them up and down.
      The pins being discolored isn’t good and it would be good to replace them.
      The diameter on the full floating rod Gen. 4 models is about .9431 inch, which is smaller than the old .9449 in. press fit pins.

  3. were all lq9 engines full floating pistons
    Bill

    • Hi Bill, we have found no evidence that LQ9s ever came with anything other than full floating piston pins. Of note, the LS6 came along in 2001 (one year earlier) and had the same.

  4. Is there any difference between a 2002 LQ9 and a 2006 LQ9? Is a 4l60e or 4l80e better to go behind it? And last how much boost can a stock LQ9 handle? I want to install a turbocharger and don’t want to push it over the edge! Thanks

  5. Hello Marcus,

    I have a built 4L60E behind my turbo LQ9 installed in an 08 Tahoe. I have no problems up to 7-8 psi (which is all I’m running for now).

    All stock rotating assembly and valvetrain too.

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