LS Engines

LM7 5.3L Vortec 5300 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More

The LM7 is a 5.3L, Gen. 3 small block engine used in GM trucks between 1999 and 2007. For marketing purposes, it was also known as the Vortec 5300. The information listed here is for the stock LM7 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.

[Trying to find an LS engine? Check out Part 1 and Part 2 of our LS Spotter’s Guide.]

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 Chevy LM7 LS truck engine.

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

GM LM7 Engine Specs

LM7 Engine Ratings
Compression Ratio9.5:1
Horsepower Rating270-295 hp
Torque Rating315-335 ft.-lbs.
LM7 Applications
VIN 8th DigitYearMakeModel
T1999-2007ChevroletSilverado 1500
T1999-2007GMCSierra 1500
T1999-2006ChevroletTahoe
T1999-2006ChevroletSuburban 1500
T1999-2006GMCYukon
T1999-2006GMCYukon XL 1500
T2002-2005CadillacEscalade (2WD)
T2002-2006ChevroletAvalanche
T2003-2007ChevroletExpress
T2003-2007GMCSavana
LM7 Block Specs
Casting Numbers12567392, 12567393, 12551358
MaterialIron
Displacement5.3L / 325 c.i.d.
Bore Dia. 3.780 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.
LM7 Rotating Assembly Specs
Piston MaterialHypereutectic Cast Aluminum Alloy
Piston StyleDished
Piston Volume+8cc
Wrist Pin Dia. (1999-2004)0.9447 in., 0.9448 in. (Pressed)
Wrist Pin Dia. (2005-07)0.9429 in., 0.9431 in (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 Journal Dia.2.559 in.
Crankshaft Rod Journal Dia.2.100 in.
Reluctor Wheel24X
Flexplate Mounting Flange0.857 in.
LM7 Cylinder Head Specs
Casting Numbers862, 706
MaterialAluminum
Combustion Chamber Volume61cc
Intake Port ShapeCathedral
Intake Runner Volume200cc
Exhaust Port ShapeOval
Exhaust Runner Volume70cc
Intake Valve Diameter1.890 in.
Exhaust Valve Diameter1.550 in.
Cylinder Head Bolt StyleTorque 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 (2004-06)(10) M11 x 2 x 100, (5) M8 x 1.25 x 45
LM7 Camshaft Specs
Years19992000-06
Duration @ .050 in. (int./exh.)191°/190°191°/190°
Valve Lift (int./exh.)0.457 in./0.466 in.0.457 in./0.466 in.
Lobe Separation Angle115.5°114°
Cam Gear Attachment3-Bolt3-Bolt
LM7 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.1.890 in.
Exhaust Valve MaterialSteel, Solid Stem
Exhaust Valve Dia.1.550 in.
LM7 Throttle Body, Fuel Injector Specs & More
Intake ManifoldTruck Style
Throttle Body78mm, 3-Bolt
Throttle Control (1999-2002)Throttle Cable
Throttle Control (2003-04)Electronic, Drive-by-Wire (most models)
Fuel Injector Flow (1999)21.8 lbs./hr.
Fuel Injector Flow (2000)24.8 lbs./hr.
Fuel Injector Flow (2001-07)25.2 lbs./hr.
Fuel Injector Length Between O-Rings 1.9 in.
Fuel Injector Connector Mini-Delphi / Multec2
PCMWarren
Crankshaft Reluctor Ring24x
Camshaft Sensor LocationRear 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.

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