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LR4

LR4 Vortec 4.8L V8 "GEN III"

Vehicle Applications

  • 1999–2006 Chevrolet Silverado 1500
  • 1999–2006 GMC Sierra 1500
  • 2005–2006 Chevrolet Tahoe
  • 2006–2006 GMC Yukon 
  • 2003–2006 Chevrolet Express 
  • 2003–2006 GMC Savana 

Product Highlights

  • Gen III Iron Cylinder Block
  • Cathedral Port Aluminum Cylinder Heads
  • Drve By Cable (Mechanical Throttle) 1999-2002
  • Drive By Wire (Electronic Throttle) 2003-2004 phased in on most models
  • 24X Ignition Systems


LR4 Engine Specs (VIN "V")

The information listed here is for the stock engine.

Performance Specifications
Compression Ratio 9.4:1
Horsepower Rating 255-280 hp
Torque Rating 285-295 ft./lbs.

 

Application Information

VIN 8th Digit

Year

Make

Model

V

1999-2006

Chevrolet

Silverado 1500

GMC

Sierra 1500

2000-2006

Chevrolet

Tahoe

GMC

Yukon

2003-2006

Chevrolet

Express

GMC

Savana

 

Engine Block Specifications
Casting Numbers

12567392, 12567393, 12551358
Material

Iron
Displacement

4.8L / 293 c.i.d.
Bore Dia.

3.780 in.
Stroke

3.267 in.
Deck Height

9.230-9.240 in.
Bore Spacing

4.400 in.
Thrust Bearing Location

#3 Main
Main Cap Style

6-Bolt
Main Housing Bore Diameter

2.751 in.
Cam Housing Bore Diameter

Bore 1/5 = 2.326, Bore 2/4 = 2.317, Bore 3 = 2.307 (1999-2003)

Bore 1/5 = 2.346, Bore 2/4 = 2.326, Bore 3 = 2.307 (2004-2007)
Cam-to-Crank Centerline

4.914 in.

 

Rotating Assembly Specifications
Piston Material

Hypereutectic Cast Aluminum Alloy
Piston Style

Flat Top
Piston Volume

0cc
Wrist Pin Dia. (1999-2004)

0.9447 in., 0.9448 in. (Pressed)
Wrist Pin Dia. (2005-2006)

0.9429 in., 0.9431 in. (Floating)
Connecting Rod Material

Powdered Metal
Connecting Rod Style

I-Beam
Connecting Rod Length

6.275 in.
Connecting Rod Bolts

M9 x 1 x 43
Crankshaft Material

Cast Iron
Crankshaft Main Journal

2.559 in.
Crankshaft Rod Journal

2.100 in.
Reluctor Wheel

24x
Flywheel Mounting Flange (1999-2000)

1.250 in.
Flexplate Mounting Flange (1999-2000)

0.857 in.
Flexplate Mounting Flange (2001-2006)

0.857 in.

 

Cylinder Head Specifications
Years

1999-2006
Casting Numbers

862,706
Material

Aluminum
Combustion Chamber Volume

61cc
Intake Port Shape

Cathedral
Intake Runner Volume

200cc
Exhaust Port Shape

Oval
Exhaust Runner Volume

70cc
Intake Valve Diameter

1.890 in.
Exhaust Valve Diameter

1.550 in.
Cylinder Head Bolt Style

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 (2004-2006)

(10) M11 x 2 x 100, (5) M8 x 1.25 x 45

 

Camshaft Specifications
Years

1999

2000-2006
Duration at .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 Angle (in degrees)

115.5

114
Cam Gear Attachment

3-Bolt

3-Bolt

 

Valvetrain Specifications
Lifter Style

Hydraulic Roller
Lifter Link Style

Plastic Lifter Tray
Lifter Body Diameter

0.842 in.
Pushrod Length

7.385 in.
Rocker Arm Mounting Style

Pedestal
Rocker Arm Style

Die-Cast, Roller Fulcrum
Rocker Ratio

1.7
Rocker Offset

None
Valve Spring Style

Beehive
Valve Spring Color

Natural
Valve Angle

15 Degrees
Intake Valve Material

Steel - Solid Stem
Intake Valve Dia.

1.890 in.
Exhaust Valve Material

Steel - Solid Stem
Exhaust Valve Dia.

1.550 in.

 

Other Specifications
Intake Manifold

Truck Style
Throttle Body

78mm, 3-Bolt
Throttle Control

All Cable Operated, 1999-2002

Drive-by-Wire phased in 2003-2004, on most models
Fuel Injector Flow

1999 = 21.8 lb/hr @ 58 psi

2000 = 24.8 lb/hr @ 58 psi

2001-06 = 25.2 lb/hr @ 58 psi
Fuel Injector Length (between O-Rings)

1.900 in.
Fuel Injector Connector

Mini-Delphi / Multec2
PCM

Warren
Crankshaft Reluctor Ring

24x
Camshaft Sensor

Rear Mount, 1x on cam
Oil Pan

Deep Rear Sump
Oil Pump

Standard Volume


LR4 Harnesses