The GM / Chevy LM4 is a 5.3 l (325 cu.in.) natural aspirated V8 90° four-stroke gasoline engine from a Generation III small block V8 truck engine series. The LM4 engine is an aluminum block version of the LM7 and it was produced from 2003 to 2005.
The GM LM4 Vortec 5300 features a V8 90° aluminum cylinder block with a five-bearings crankshaft, two aluminum heads, a single one-piece cast camshaft, and two valves per cylinder (16 in total). The LM4 has a sequential multi-port fuel injection system and a 78.0 mm electronic throttle body. The engine used a “Coil-Near-Plugs” ignition system with a composite distributor, low-resistance spark plug wires, and platinum-tipped spark plugs.
The compression ratio rating is 9.5:1. Cylinder bore and piston stroke are 96.0 mm (3.78 in) and 92.0 mm (3.62 in), respectively. The engine produced from 294 PS (216 kW; 290 HP) at 5,200 rpm to 304 PS (224 kW; 300 HP) at 5,200 rpm. The LM4 Vortec 5.3 engine has a torque rating between 441 N·m (45.0 kg·m, 325 ft·lb) at 4,000 rpm and 454 N·m (46.3 kg·m, 335 ft·lb) at 4,000 rpm.
General information
| Engine Specifications | |
| Engine code | GM / Chevy LM4 Vortec 5300 |
| Layout | Four stroke, V8 |
| Fuel type | Gasoline (petrol) |
| Production | 2002-2005 |
| Displacement | 5.3 L, (325 cu in) |
| Fuel system | Sequential multi-port fuel injection |
| Power adder | None |
| Power output | 294 PS (216 kW; 290 HP) at 5,200 rpm 304 PS (224 kW; 300 HP) at 5,200 rpm |
| Torque output | 441 N·m (45.0 kg·m, 325 ft·lb) at 4,000 rpm 454 N·m (46.3 kg·m, 335 ft·lb) at 4,000 rpm |
| Firing order | 1-8-7-2-6-5-4-3 |
| Dimensions (L x W x H): | – |
| Weight | – |
Cylinder block
The GM LM4 Vortec has an aluminum cylinder block with a five-bearings crankshaft supported system. The crankshaft journal diameter is 65.0 mm (2.55 in), the crankpin diameter is 53.3 mm (2.09 in).
The cylinder bore is 96.0 mm (3.78 in), piston stroke is 92.0 mm (3.62 in) and the compression ratio rating is 9.5:1. The GM LM4 motor has two compression and one oil control rings. The connecting rod’s length is 154.89 mm (6.098 in).
| Cylinder block | ||
| Cylinder block alloy | Aluminum | |
| Compression ratio: | 9.5:1 | |
| Cylinder bore: | 96.0 mm (3.78 in) | |
| Piston stroke: | 92.0 mm (3.62 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Number of main bearings: | 5 | |
| Cylinder inner diameter (standard): | 96.000-96.018 mm (3.7795-3.7802 in) | |
| Piston skirt diameter (standard): | 96.000 mm (3.7795 in) | |
| Piston pin outer diameter: | 23.997-24.000 mm (0.9448-0.9449 in) (2003-2004) 23.950-23.957 mm (0.9429-0.9431 in) (2005) | |
| Piston ring side clearance: | Top | 0.045-0.080 mm (0.0018-0.0031 in) |
| Second | 0.040-0.078 mm (0.0016-0.0031 in) | |
| Oil | 0.012-0.200 mm (0.0005-0.0079 in) | |
| Piston ring end gap: | Top | 0.23-0.44 mm (0.0091-0.0173 in) |
| Second | 0.44-0.70 mm (0.0173-0.0276 in) | |
| Oil | 0.18-0.75 mm (0.0071-0.0295 in) | |
| Connecting rod small end diameter | 24.000 mm (0.9449 in) | |
| Connecting rod big end diameter: | 56.505-56.525 mm (2.2246-2.2254 in) | |
| Connecting rod center distance: | 159.38 mm (6.275 in) | |
| Crankshaft main journal diameter: | 64.993-65.007 mm (2.5588-2.5593 in) | |
| Crankpin diameter: | 53.318-53.338 mm (2.0991-2.0999 in) | |
| Crankshaft center distance: | 46 mm (1.81 in) | |
Cylinder head
The cylinder heads are made of strong, light aluminum alloy which gives it good cooling efficiency. It LM4 Vortec 5.3 uses 862 or 706 cylinder heads. The camshaft is driven by a single chain. The timing chain transmits the rotational movement from the crankshaft to the camshafts. Valves are operated via pedestal mounting rocker arms.
The intake valve diameter is 48.0 mm (1.89 in) the exhaust valve diameter is 39.4 mm (1.55 in), respectively. The intake duration is 190°, and the intake valve lift is 11.60 mm (0.457 in), the exhaust duration is 191°, the exhaust valve lift is 11.84 mm (0.466 in). The lobe separation angle is 114°.
| Cylinder head | ||
| Block head alloy | Aluminium | |
| Valve Arrangement: | OHV, chain drive | |
| Cylinder head height: | 120.2 mm (4.7323 in) | |
| Valves: | 16 (2 valves per cylinder) | |
| Intake valve timing: | 190° | |
| Exhaust valve timing: | 191° | |
| Valve head diameter: | INTAKE | 48.0 mm (1.8898 in) |
| EXHAUST | 39.4 mm (1.5512 in) | |
| Valve length: | INTAKE | – |
| EXHAUST | – | |
| Valve stem diameter: | INTAKE | 7.955-7.976 mm (0.3132-0.314 in) |
| EXHAUST | 7.955-7.976 mm (0.3132-0.314 in) | |
| Valve spring free length: | INTAKE | 52.9 mm (2.0827 in) |
| EXHAUST | 52.9 mm (2.0827 in) | |
| Camshaft lobe lift: | INTAKE | 6.96 mm (0.274 in) |
| EXHAUST | 6.82 mm (0.2685 in) | |
| Camshaft journal diameter: | 54.99-55.04 mm (2.165-2.1669 in) | |
Head tightening procedure and torque specs:
- Step 1: 30 Nm (3.06 kg·m; 22.14 ft·lb)
- Step 2: Turn all bolts: 90°
- Step 3: Turn all bolts excluding the medium length bolts at the front and rear of each head: 90°
- Step 4: Turn all medium length bolts at the front and rear of each head: 50deg;
Maintenance data
| Compression pressure | |
| Standard | 12.5 kg/m2 / 300 rpm |
| Minimun | 7.0 kg/m2 / 300 rpm |
| Compression differential limit between cylinders | 1.0 kg/m2 (15 psi) / 300 rpm |
| Oil system | |
| Oil consumption , L/1000 km (qt. per miles) | up to 0.5 (1 qt. per 1200 miles) |
| Recommended engine oil | 5W-30, 10W-30 |
| Oil type API | – |
| Engine oil capacity (Refill capacity) | 5.7 L (6.02 US. qt, 5.02 Imp. qt.) |
| Oil change interval, km (miles) | 12,000 km (7,500 miles) |
| Oil Pressure | 41 kPa at 1,000 rpm 124 kPa at 2,000 rpm 165 kPa at 4,000 rpm |
| Ignition system | |
| Spark plug | AC Delco: 41-985 Iridium |
| Spark plug gap | 1.01 mm (0.0398 in) |
Vehicle applications
| Model | Years Produced |
| Chevrolet TrailBlazer EXT | 2003–2005 |
| Isuzu Ascender | 2003–2004 |
| GMC Envoy XL | 2003-2004 |
| Chevrolet SSR | 2003–2004 |
| Buick Rainier | 2004 |
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