LS Engines

LH9 5.3L Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More

(Image/GTcarlot.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 specific guide is for the GM LH9 5.3L engine.

You can find more LS engine spec guides and LS-related information here.

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

LH9 5.3L Engine Specs

The LH9 engine is a 5.3L, Gen. 4, aluminum small block engine used in GM trucks and SUVs between 2010-2012, including the 2010 Hummer H3.

In 2010, the LH8 was replaced by the LH9. The LH9 was upgraded with VVT and flex fuel capability. It was available in the H3 for 2010. It was also available in the mid-size pickups until 2012. Like the other 5.3L engines, it was known as the Vortec 5300.

The information listed here is for a stock engine.

LH9 Performance Specifications

LH9 Engine Ratings
Compression Ratio9.6:1
Horsepower Rating300 hp
Torque Rating320 ft.-lbs.

LH9 Applications

LH9 Applications
VIN 8th DigitYearMakeModel
P2010HummerH3
P2010-12ChevroletSilverado 1500
P2010-12GMCSierra 1500

LH9 Engine Block Specs

LH9 Block Specs
Casting Number125771048, 12601900, 12569513, 12568573
MaterialAluminum
Displacement5.3L / 325 c.i.d.
Bore Dia. 3.780 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. Bore 1/5 = 2.346 in. Bore 2/4 = 2.326 in. Bore 3 = 2.307 in.
Cam-to-Crank Centerline4.914 in.

LH9 Rotating Assembly

LH9 Rotating Assembly Specs
Piston MaterialHypereutectic Cast Aluminum Alloy
Piston StyleFlat Top with valve reliefs
Piston Volume3cc
Wrist Pin Dia.0.9431 in. (Full Floating)
Connecting Rod MaterialPowdered Metal
Connecting Rod StyleI-Beam
Connecting Rod Length6.098 in.
Connecting Rod Housing Bore2.225 in.
Connecting Rod BoltsM9 x 1 x 43
Connecting
Rod Part Number
12649190
Connecting Rod Casting Number (last three digits)143
Crankshaft MaterialCast Iron
Crankshaft Part Number
(Last 3 Digits)
12588614
Crankshaft Casting Number (last three digits)216
Crankshaft Main Journal Dia.2.559 in.
Crankshaft Rod Journal Dia.2.100 in.
Reluctor Wheel58x

LH9 Cylinder Heads

LH9 Cylinder Head Specs
Casting Numbers799, 243
MaterialAluminum
Combustion Chamber Volume65cc
Intake Port ShapeCathedral
Intake Runner Volume210cc
Exhaust Port ShapeD-Port
Exhaust Runner Volume75cc
Intake Valve Diameter2.000 in.
Exhaust Valve Diameter1.575 in.
Cylinder Head Bolt StyleTorque to Yield (TTY)
Cylinder Head Bolt Size (10) M11 x 2 x 100, (5) M8 x 1.25 x 45

LH9 Camshaft Specs

Part Number12625437
Duration @ .050 in. (int./exh.)190°/191°
Valve Lift (int./exh.)0.457 in./0.466 in.
Lobe Separation Angle114°
Cam Gear Attachment1-Bolt
Cam Gear Poles4x
Active Fuel Management (AFM)No
Variable Valve Timing (VVT)Yes

LH9 Valvetrain

LH9 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.1.575 in.
Timing Chain Guide StyleSpring Loaded Tensioner

LH9 Throttle Body, Fuel Injector Specs & More

Intake ManifoldTruck-Style
Throttle Body87mm, 4-bolt
Throttle Control Electronic, Drive-by-Wire
Fuel Injector Part Number 12613411
Fuel Injector Flow37 lb./hr. @ 58 psi
Flex Fuel CapableYes
Fuel Injector Length Between O-Rings 1.700 in.
Fuel Injector Connector EV6 / USCAR
PCME67
Crankshaft Reluctor Ring58x
Camshaft Sensor LocationTiming Cover
Oil Pan
Varies by Application
Oil PumpHigh Volume
(1.25 c.i. per rev.)
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2 Comments

  1. Pingback: LH9 5.3L Engine Upgrade Guide: Expert Advice for LH9 Mods to Maximize Performance

  2. Where can I buy one of these complete engines? Will it be compatable with a 2008 Hummer H3 Luxury?

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