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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)
| 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 | |
| Vehicle | Transmission |
|---|---|
| Chevrolet Express (3 Door Cargo) | M30-4L60E |
| GMC Savana (3 Door Cargo) | M30-4L60E |
