mobile-menu-icon
GM Authority

GM 4.3 Liter V6 Vortec LU3 Engine

The 4.3L V6 Vortec LU3 is an engine produced by General Motors for use in full-size light-duty pickup truck and vans. Displacing 4.3 liters in a V6 configuration, the LU3 served as the standard (base) powerplant for GM’s GMT900-based full-size pickup trucks (Chevrolet Silverado 1500 and GMC Sierra 1500) and continues to be the base powerplant for the Chevrolet Express and GMC Savana full-size vans. The arrival of the all-new K2XX-based 2014 Chevrolet Silverado and 2014 GMC Sierra brought with it an all-new base engine — the 4.3-liter V6 EcoTec3 LV3. As such, the LU3 is now only produced for the Express and Savana vans.

The LU3 features excellent torque, fuel efficiency, durability, low cost of ownership, and steady improvement — all of which contribute to its popularity as a base engine in GM’s light-duty full-size vans. A counter-rotating balance shaft helps balance primary crank vibration, while the latest in electronic controls and the inherent low-end torque delivery of this overhead-valve engine have combined to make the engine very popular.

Engine highlights:

  • Cylinder Block and Rotating Assembly: the LU3 features an iron cylinder block based on the small-block V8 architecture. Inside the block, the rotating assembly consists of a strong iron crankshaft, lightweight aluminum pistons and cracked powder-metal connecting rods.
  • Electronic Direct Ignition System: a trio of ignition coils is mounted above the former location of the conventional distributor (a unique “stub” shaft is used to drive the oil pump). Each coil is directed by the engine’s controller to fire two cylinders. The ignition system uses a 58X crankshaft-sensing reluctor wheel, similar to those used in GM’s Gen IV V8 engines.
  • Additional details: The LU3 incorporates a number of features designed to optimize performance and durability, while helping keep down ownership costs. They include:
    • Machined water pump and specific gasket delivers better pump-to-block sealing
    • Cast rocker arms offer more precise tolerances
    • Low-permeable intake sealing system helps ensure minimal fuel emissions seeping out of the intake system
    • Three layers of insulated tubing for the exhaust manifolds helps reduce noise
    • Extended-life spark plugs are designed to go 100,000 miles (160,000 km) without the need for replacement
    • Extended-life Dex-Cool coolant maintains its cooling and corrosion-inhibiting properties for 150,000 miles (240,000 km)
GM 4.3L V6 Vortec LU3 Engine Specs
Type: 4.3L Gen1e V6 (LU3)
Displacement: 4300cc (262 ci)
Engine Orientation: Longitudinal
Compression ratio: 9.2:1
Valve configuration: Overhead valves
Valves per cylinder 2
Assembly site: Romulus, Michigan, USA
Valve lifters: Hydraulic roller
Firing order: 1 – 6 – 5 – 4 – 3 – 2
Bore x Stroke: 101.6 x 88.39 mm
Fuel system: Sequential fuel injection
Fuel type: Regular unleaded
Horsepower hp (kW)
Chevrolet Express: 195 hp (145 kW) @ 4600 RPM
GMC Savana: 195 hp (145 kW) @ 4600 RPM
Torque lb.-ft. (Nm)
Chevrolet Express: 260 lb.-ft. (353 Nm) @ 2800 RPM
GMC Savana: 260 lb.-ft. (353 Nm) @ 2800 RPM
Maximum Engine Speed: 5600 RPM
Emissions controls
Evaporative system
Bin 5 emissions (see additional features in Engine Overview)
Returnless fuel system
Materials
Block: Cast iron
Cylinder head: Cast iron
Intake manifold
Upper: Composite
Lower: Cast aluminum
Exhaust manifold: High silicon molybdenum and cast nodular iron
Main bearing caps: Cast iron
Crankshaft: Cast iron
Camshaft: Steel
Connecting rods: Powder metal (2006 interim implementation)
Additional features
Investment cast roller rocker arms
Extended life spark plugs
Three layer exhaust shields
Extended life coolant
GF4 oil
Dual close coupled 102 converters (Bin 5 emissions)
4X cam timing
58X crank timing
Dual knock sensors
Threaded block heater
Oil pump stub shaft
Oil pan with noise abatement ribs
Electronic throttle control
Aluminum front cove
DIS ignition system
GM 4.3L V6 Vortec LU3 Engine Vehicle Applications
Vehicle Transmission
Chevrolet Express (3 Door Cargo) M30-4L60E
GMC Savana (3 Door Cargo) M30-4L60E
[nggallery id=”626″]

Subscribe to GM Authority

For around-the-clock GM news coverage

We'll send you one email per day with the latest GM news. It's totally free.