BMW M52B25

BMW M52B25The BMW M52B25 is a 2.5 L (2,494 cc, 152.2 cu·in) straight-six, natural aspirated four-stroke gasoline engine, manufactured by BMW from 1995 to 2000.

The cylinder bore is 84.0 mm (3.31 in) and the piston stroke is 75.0 mm (2.95 in). The compression ratio rating is 10.5:1.

The M52B25 engine produced 170.0 PS (125 kW; 167.6 HP) at 5,500 rpm of maximum horsepower and 245 N·m (25 kg·m, 180.6 ft·lb) at 3,500 rpm of maximum torque.

The BMW M52B25 features:

  • Cast-aluminum alloy cylinder block with Nikasil coated cylinder liners
  • Aluminum cylinder head
  • DOHC design with 4 valves per cylinder (24 valves in total)
  • Distributorless ignition system with individual ignition coils for each cylinder ignition system
  • Electronic fuel injection (EFI)
  • Siemens MS 41.0, DME (Digital Motor Electronics) system
  • Single VANOS (Variable Valve Timing System from BMW)

General information

Engine Specifications
Engine modelM52B25
Engine typeStraight-six, 4-stroke, DOHC
Displacement2.5 L, 2,494 cm3, (152.2 cu·in)
Max. horsepower170 PS (125 kW; 167.6 HP) at 5,500 rpm
Max. torque245 N·m (25 kg·m, 180.6 ft·lb) at 3,500 rpm
Cooling systemLiquid-cooled
Lubricating systemPressure feed
Ignition systemDistributorless ignition system with individual ignition coils for each cylinder
Fuel systemElectronic fuel injection (EFI)
Starting systemStarter 12V
Firing order:1-5-3-6-2-4
Dry weight158 kg(348 lbs)

Cylinder Block and Head

Cylinder block
Cylinder block alloy:Aluminium
Compression ratio:10.5:1
Cylinder bore:84.0 mm (3.31 in)
Piston stroke:75.0 mm (2.95 in)
Cylinder internal diameter (standard):84.000-84.010 mm (3.3071-3.3075 in)
Piston skirt outer diameter (standard):83.980-83.989 mm (3.3063-3.3066 in)
Number of piston rings (compression / oil):2/1
Piston pin diameter:22.000 mm (0.8661 in)
Side clearance (Top):0.020-0.060 mm (0.0008-0.0024 in)
Side clearance (Second):0.030-0.065 mm (0.0012-0.0026 in)
Side clearance (Oil):0.020-0.060 mm (0.0008-0.0024 in)
Ring end gap (Top):0.100-0.300 mm (0.0039-0.0118 in)
Ring end gap (Second):0.200-0.400 mm (0.0079-0.0157 in)
Ring end gap (Oil):0.250-0.500 mm (0.0098-0.0197 in)
Number of main bearings:7
Crankshaft main journal diameter:60.000 mm (2.3622 in)
Crankpin journal diameter:45.000 mm (1.7717 in)
Crankshaft center distance:37.50 mm (1.475 in)
Cylinder head
Cylinder head alloy:Aluminium
Valve arrangement:DOHC, chain driven
Valves:4, (24 valves in total)
Head height:140.0 mm (5.5118 in)
Valve head diameter (INTAKE):33.0 mm (1.2992 in)
Valve head diameter (EXHAUST):30.5 mm (1.2008 in)
Valve steam diameter (INTAKE):6.0 mm (0.2362 in)
Valve steam diameter (EXHAUST):6.0 mm (0.2362 in)

Service Data

Compression pressure
Minimum:10.0 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
Lubrication system:Pressure feed
Oil type:BMW High Performance Synthetic (API SH)
Recommended oil:SAE 5W-30
Oil 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)
Fuel system
Type:Electronic fuel injection (EFI)
Ignition system
Type:Distributorless ignition system with individual ignition coils for each cylinder
Spark plug:Bosch: FGR7DQP, NGK: BKR6EQUP
Spark plug torque:25 N·m (2.5 kg·m, 18.4 ft·lb)

Applications

ModelYears Produced
BMW 323i (E36)1995-1998
BMW 323ti (E36/5)1995-2000
BMW 523i (E39)1995-2000

References

1. BMW TIS (Technical Information System)

Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

ATTENTION! Dear visitors, this is an informational database of technical specifications, we are not a parts supplier or a marketplace.

We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.

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