BMW M52B20

BMW M52B20The BMW M52B20 is a 2.0 liters (1,991 cc, 121.5 cu-in) straight-six, four-stroke cycle natural aspirated gasoline engine from BMW M52-family. The engine was manufactured on Munich Plant (Munich, Germany) from 1994 to 1998.

The M52B20 engine features a cast-aluminum alloy cylinder block with Nikasil coated cylinder liners. The aluminum cylinder head uses chain-driven double overhead camshafts (DOHC) and four valves per cylinder (24 valves in total). It is equipped with a Siemens MS 41.0, DME (Digital Motor Electronics) system, VANOS (Variable Valve Timing System from BMW) and a distributorless ignition system with individual ignition coils for each cylinder.

Cylinder bore and piston stroke are 80.0 mm (3.15 in) and 66.0 mm (2.6 in), respectively. Compression ratio rating is 11.0: 1. The BMW M52B20 engine produced 150 PS (110 kW; 148 HP) at 5,900 rpm of maximum horsepower and 190 N·m (19.4 kg·m, 140 ft·lb) at 4,200 rpm of peak torque.

The breakdown of the engine code is as follows:

  • M52 – Engine Family
  • B – Gasoline
  • 20 – 2.0 Liter Displacement

General information

Engine Specifications
Engine codeM52B20
LayoutFour stroke, Inline-6 (Straight-6)
Fuel typeGasoline
Production1994-1998
Displacement2.0 L, 1,991 cc (121.5 cu in)
Fuel systemFuel injection system
Power adderNone
Max. horsepower150 PS (110 kW; 148 HP) at 5,900 rpm
Max. torque190 N·m (19.4 kg·m, 140 ft·lb) at 4,200 rpm
Firing order1-5-3-6-2-4
Dimensions (L x H x W):
Weight~158 kg(348 lbs)

Cylinder block

The M52B20 cylinder block is cast aluminum alloy with Nikasil coated cylinder liners. The cylinder bore is 80.0 mm (3.15 in) and the piston stroke is 66.0 mm (2.6 in). The cylinders are exposed on all sides to circulating coolant. The counterweighted crankshaft rotates in replaceable split-shell main bearings. This engine used seven main bearings.

The forged steel connecting rods use replaceable split-shell bearings at the crankshaft end and solid bushings at the piston pin end. The pistons are of the three-ring type with two upper compression rings and a lower one-piece oil scraper ring. Full-floating piston pins are retained with circlips. The compression ratio rating is 11.0:1.

Cylinder block
Cylinder block alloyAluminum alloy
Compression ratio:11.0:1
Cylinder bore:80.0 mm (3.15 in)
Piston stroke:66.0 mm (2.60 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:7
Cylinder inner diameter (standard):80.000-80.010 mm (3.1496-3.15 in)
Piston skirt diameter (standard):79.985-79.994 mm (3.149-3.1494 in)
Piston pin outer diameter:22.000 mm (0.8661 in)
Piston ring side clearance:Top0.020-0.055 mm (0.0008-0.0022 in)
Second0.020-0.055 mm (0.0008-0.0022 in)
Oil0.020-0.055 mm (0.0008-0.0022 in)
Piston ring end gap:Top0.100-0.300 mm (0.0039-0.0118 in)
Second0.200-0.400 mm (0.0079-0.0157 in)
Oil0.200-0.400 mm (0.0079-0.0157 in)
Crankshaft journal diameter:60.000 mm (2.3622 in)
Crankpin diameter:45.000 mm (1.7717 in)

Cylinder head

The cylinder head is made of an aluminum alloy with good cooling efficiency. The M52B20 engine uses chain-driven double overhead camshafts and four valves per cylinder. Standart head height is 140.0 mm (5.5118 in). The cylinder head employs a crossflow design for greater power and efficiency. Intake air enters the combustion chamber from one side while exhaust gasses exit from the other. This engine is equipped with a single VANOS (Variable Camshaft Timing) system.

Intake valves are 30.0 mm (1.1811 in) in diameter and exhaust valves are 27.0 mm (1.063 in). Valve clearance is set by self-adjusting (zero-lash) hydraulic lifters for reduced valve noise and the elimination of routine valve adjustment.

Cylinder head
Cylinder head alloyAluminum
Valve Arrangement:DOHC, chain driven
Valves:24 (4 valves per cylinder)
Intake/Exhaust duration:228°/228°
Valve head diameter:INTAKE30.0 mm (1.1811 in)
EXHAUST27.0 mm (1.063 in)
Valve steam diameter:INTAKE6.0 mm (0.2362 in)
EXHAUST6.0 mm (0.2362 in)

Head tightening procedure and torque specs:

  • Step 1: 40.0 Nm; 4.1 kg·m; 29.5 ft·lb
  • Step 2: Turn all bolts 90°
  • Step 3: Turn all bolts another 90°

Maintenance data

Compression pressure
Minimum10.0 kg/cm2 (9.9 bar, 145 psi) / 350 rpm
Compression differential limit between cylinders:1.0 kg/cm2 (1.0 bar, 15 psi) / 350 rpm
Oil system
Recommended engine oil SAE 5W-30
Oil typeBMW LL-01 or LL98
Engine oil capacity (Refill capacity)~ 6.5 L (6.87 US. qt, 5.72 Imp. qt.)
Oil change interval, km (miles)5,000-10,000 (3,000-6,000)
Ignition system
Spark plugBosch: FBLDCR
Spark plug torque:25 N·m (2.5 kg·m, 18.4 ft·lb)

Vehicle applications

ModelYears Produced
BMW 320i (E36)1994-1998
BMW 520i (E39)1995-1998
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