Vehicle Applications

• 2003–2005 Cadillac Trailblazer EXT
• 2003–2004 Chevrolet SSR
• 2003–2004 GMC Envoy XL
• 2004 Buick Rainier
• 2003–2004 Isuzu Ascender

Product Highlights

• Gen III Aluminum Cylinder Block
• Cathedral Port Aluminum Cylinder Heads
• Drive By Wire (Electronic Throttle) 
• 24X Ignition Systems

LM4 Engine Specs (VIN "P")

Performance Specifications
Compression Ratio	9.5:1
Horsepower Rating	290-300 hp
Torque Rating	325-335 ft./lbs.

 

Application Information
VIN 8th Digit	Year	Make	Model
P	2003-2005	Chevrolet	Trailblazer EXT
	2003-2004	Chevrolet	SSR
		GMC	Envoy XL
	2004	Buick	Rainier
	2003-2004	Isuzu	Ascender

 

Engine Block Specifications
Casting Numbers	12566910
Material	Aluminum
Displacement	5.3L / 325 cid
Bore Dia.	3.780 in.
Stroke	3.622 in.
Deck Height	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	(2003) Bore 1/5 = 2.326, Bore 2/4 = 2.317, Bore 3 = 2.307
	(2004-2005) Bore 1/5 = 2.346, Bore 2/4 = 2.326, Bore 3 = 2.307
Cam-to-Crank Centerline	4.914 in.

 

Rotating Assembly Specifications
Piston Material	Hypereutectic Cast Aluminum Alloy
Piston Style	Dished
Piston Volume	+8cc
Wrist Pin Dia. (2003-2004)	0.9447 in., 0.9448 in. (Pressed)
Wrist Pin Dia. (2005)	0.9429 in., 0.9431 in (Floating)
Connecting Rod Material	Powdered Metal
Connecting Rod Style	I-Beam
Connecting Rod Length	6.098 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

 

Cylinder Head Specifications
Years	2003-2005
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 (2003)	(8) M11 x 2 x 155, (2) M11 x 2 x 100, (5) M8 x 1.25 x 45
Cylinder Head Bolt Size (2004-2007)	(10) M11 x 2 x 100, (5) M8 x 1.25 x 45

 

Camshaft Specifications
Years	2003-2005
Duration at .050 in (int./exh)	191/190
Valve Lift (int./exh)	0.457 in./0.466 in.
Lobe Separation Angle (in degrees)	114
Cam Gear Attachment	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	Drive-by-Wire
Fuel Injector Flow	25.2 lb/hr @ 58 psi
Fuel Injector Length (between O-Rings)	1.900 in.
Fuel Injector Connector	Mini-Delphi / Multec2
Fuel Rail	2003 Return Style, 2004-2005 Returnless
PCM	Warren
Crankshaft Reluctor Ring	24x
Camshaft Sensor	Rear Mount, 1x on cam
Oil Pan	Front Sump, tunnel in pan for 4wd, center filter
Oil Pump	Standard Volume