(Image/Summit Racing – Mopar Replacement)

When Chrysler announced it was bringing back the legendary Hemi in the early 2000s, it was a big deal. This new series of Hemi engines is often referred to as the “Gen. 3” after the first generation FirePower (1951-59) and second generation Elephant 426 (1964-71).

Note: This Spec Guide is part of a series of Hemi Engine Spec guides we’re putting together. See Other Hemi Engine Spec Guides Here.

The Hemi Returns!

The first edition of the third generation Mopar Hemi engine made its debut in 2003 Dodge Ram trucks and featured a 5.7 liter (345 cubic inch) displacement.

Still considered a small-block engine based on displacement, the 5.7L Gen. III Hemi uses a hemispherical combustion chamber with two spark plugs per cylinder and small wedge flats along with excellent intake and exhaust ports.

This 5.7L engine configuration would be the basis for future Hemi displacement variations.

This Engine Guide is Specifically for the 2003-08 Mopar Gen. III 5.7L Hemi Engine.

2003-08 Mopar Gen. III 5.7L Hemi Engine Performance

Mopar 5.7L Hemi Performance Ratings
Compression Ratio9.6:19.6:1
Horsepower 345 hp340 hp
Torque375 lb.-ft.390 lb.-ft.

2003-08 Mopar Gen. III 5.7L Hemi Engine Identification

Mopar 5.7L 2003-08 Truck Engine Applications
VIN Number DigitYearMakeModel
8th digit of VIN: “D” 2003-08DodgeRam 1500

2003-08 Mopar Gen. III 5.7L Hemi Engine Block Specs

Mopar 5.7L Hemi Block Specs
Casting Numbers53021319AG
50321314 DR
Displacement5.7L / 345 c.i.d.
Bore Dia.99.5mm / 3.92"
Stroke90.9mm / 3.58"
Deck Height9.25"
Bore Spacing4.46"
Thrust Bearing LocationNumber 3
Main Cap Style2 Bolts with 2 Lateral Cross-Bolts (All 5 Mains)
Cam-to-Crank Centerline7.44"

2003-08 Mopar Gen. III 5.7L Hemi Engine Rotating Assembly

Mopar 5.7L Hemi Rotating Assembly Specs
Piston MaterialHypereutectic
Piston StyleFlat Top with Valve Notches
Piston Ring Package1.5mm, 1.5mm, 3.0mm
Wrist Pin Diameter0.9456"
Connecting Rod MaterialPowdered Metal
Connecting Rod StyleI-Beam
Connecting Rod Length6.242"
Connecting Rod Bearing Bore2.125"
Connecting Rod Bolts9.0mm x 1
Crankshaft MaterialNodular Iron
Crankshaft Part Number53021302AD
Crankshaft Casting Numbers53021319AG
Crankshaft Main Journal Dia.2.559"
Crankshaft Rod Journal Dia.2.126"
Crankshaft Reluctor Count32x
Crankshaft Mounting Flange8 Bolts

2003-08 Mopar Gen. III 5.7L Hemi Engine Cylinder Heads

Mopar 5.7L Hemi Cylinder Head Specs
Casting Numbers53021300AJ (Right)
53021300BA (Left)
Cylinder Head MaterialAluminum
Combustion Chamber Volume85cc
Combustion Chamber DesignHemispherical, with Quench & 2 Spark Plugs Per Cylinder
Intake Port ShapeSquare, with Dimple
Intake Runner Volume161cc
Exhaust Port ShapeSquare
Exhaust Port Volume50cc
Intake Valve Diameter2.00"
Exhaust Valve Diameter1.55"
Cylinder Head Bolt StyleTorque to Yield (TTY)
Cylinder Head Bolt SizeM12 x 1.5mm & 8mm

2003-08 Mopar Gen. III 5.7L Hemi Engine Camshaft Specs

Mopar 5.7L Hemi Camshaft Specs
DesignHydraulic Roller
Advertised Duration
260 / 268
Valve Lift
.0472" / .0460"
Cam Journal Dia.2.24" / 57mm Front (Smaller to the Rear)

2003-08 Mopar Gen. III 5.7L Hemi Engine Valvetrain Specs

Mopar 5.7L Hemi Valvetrain Specs
Lifter DesignHydraulic Roller
Lifter Link StylePlastic Guide x 4
Lifter Body Diameter0.842"
Pushrod LengthVaries by Application
Rocker Arm Mounting StyleShaft
Rocker Arm StyleDie Cast, Roller Fulcrum
Rocker Ratio1.60:1 (Intake)
1.66:1 (Exhaust)
Rocker OffsetNone
Valve Spring StyleBeehive
Valve Angle18° (Intake)
16.5° (Exhaust)
Intake Valve MaterialSteel, Solid Stem
Intake Valve Diameter2.00"
Exhaust Valve MaterialSteel, Solid Stem
Exhaust Valve Diameter1.55"
Valve Stem Diameter0.3125"
Timing Chain Guide StyleSpring-Loaded Tensioner

Other 2003-08 Mopar Gen. III 5.7L Hemi Engine Specs

5.7L Hemi Throttle Body, Fuel Injectors, Oil Pan Specs & More
Intake ManifoldComposite, Fixed Runner Length
Throttle Body80mm
Throttle ControlElectronic
Fuel Injector Part Number4591851AB
(& Multiple Alternates)
Fuel Injector Flow26 lb./hr. @ 58 PSI
Flex Fuel CapableNo
Fuel Injector ConnectorUSCAR, EV6
Crankshaft Reluctor Ring32 Teeth
Camshaft Sensor LocationPassenger Side, Front
Oil PanVaries by Application
Oil PumpGerotor
Variable Valve Timing (VVT)No
Multi-Displacement System (MDS)Yes, on 2005+ Models
Firing Order1-8-4-3-6-5-7-2
Total Weight, Full Dress560 lbs.
Author: Jeff Smith

Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. Now he serves as a regular contributor to OnAllCylinders.