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BMW M52B25 Engine Specifications
The BMW M52B25 is a 2.5 liters (2,494 cc, 152.20 cu-in) straight-six, four-stroke cycle naturally aspirated gasoline engine from BMW M52-family. The engine was manufactured oNmunich Plant (Munich, Germany) from 1995 to 2000. The 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. This engine has an 84.0 mm (3.31 in) cylinder bore and 75.0 mm (2.95 in) piston stroke. This engine has a compression ratio of 10.5:1 and a redline of 6,500 rpm. It produced 170 PS (125 kW; 168 HP) at 5,500 rpm of maximum horsepower and 245 Nm (25 kgm, 180.6 ft-lb) at 3,950 rpm of peak torque.
Engine code identification:
M52 - Engine Family
B - Gasoline
25 - 2.5 Liter Displacement
| GENERAL TECHNICAL DATA |
Engine model ..................... M52B25
Cylinder layout ..................... Four stroke, Inline-6 (Straight-6)
Fuel type ..................... Gasoline
Year of production ..................... 1995-2000
Total displacement ..................... 2.5 L, 2,494 cc (152.19 cubic
inches)
Fuel system ..................... Fuel injection system
Power adder ..................... None
Maximum power ..................... 170 PS (125 kW; 168 HP) at 5,500 rpm
Maximum torque ..................... 245 Nm (25 kgm, 180.6 ft-lb) at
3,950 rpm
Firing order ..................... 1-5-3-6-2-4
Dimensions (L x H x W) ..................... -
Weight ..................... 158 kg (348 lbs)
| CYLINDER BLOCK |
The M52B25 cylinder block is cast aluminum alloy with Nikasil coated
cylinder liners. Nikasil is a trademarked electrodeposited lipophilic
nickel matrix silicon carbide coating for engine components. The
cylinder bore is 84.0 mm (3.31 in) and the piston stroke is 75.0 mm
(2.95 in). The cylinders are exposed on all sides to circulating
coolant. The cast-iron counterweighted crankshaft rotates in replaceable
split-shell main bearings. This engine used seveNmain 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 10.5:1.
Cylinder block alloy ..................... Aluminum alloy
Compression ratio ..................... 10.5:1
Cylinder bore ..................... 84.0 mm (3.31 in)
Piston stroke ..................... 75.0 mm (2.95 in)
Number of piston rings (compression / oil) ..................... 2 / 1
Number of main bearings ..................... 7
Cylinder inner diameter (standard) ..................... 84.000-84.010
mm (3.3071-3.3075 in)
Piston skirt diameter (standard) ..................... 83.980-83.989 mm
(3.3063-3.3066 in)
Piston pin outer diameter ..................... 22.000 mm (0.8661 in)
Piston ring side clearance ..................... Top
..................... 0.020-0.060 mm (0.0008-0.0024 in)
Second ..................... 0.030-0.065 mm (0.0012-0.0026 in)
Oil ..................... 0.020-0.060 mm (0.0008-0.0024 in)
Piston ring end gap ..................... Top .....................
0.100-0.300 mm (0.0039-0.0118 in)
Second ..................... 0.200-0.400 mm (0.0079-0.0157 in)
Oil ..................... 0.250-0.500 mm (0.0098-0.0197 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 M52B25 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 33.0 mm (1.2992 in) in diameter and exhaust valves are
30.5 mm (1.2008 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 alloy ..................... Aluminum
Valve Arrangement ..................... DOHC, chain driven
Valves ..................... 24 (4 valves per cylinder)
Intake/Exhaust duration ..................... 228°/228°
Valve head diameter ..................... INTAKE .....................
33.0 mm (1.2992 in)
EXHAUST ..................... 30.5 mm (1.2008 in)
Valve steam diameter ..................... INTAKE .....................
6.0 mm (0.2362 in)
EXHAUST ..................... 6.0 mm (0.2362 in)
Head tightening procedure and torque specs:
Step 1: 40.0 Nm; 4.1 kgm; 29.5 ft-lb
Step 2: Turn all bolts 90°
Step 3: Turn all bolts another 90°
| MAINTENANCE 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
Recommended engine oil ..................... SAE 5W-30
Oil type ..................... BMW LL-01 or LL-01FE
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 plug ..................... Bosch: F8LDCR
Spark plug torque ..................... 25 Nm (2.5 kgm, 18.4 ft-lb)
| VEHICLE APPLICATIONS |
BMW 323i (E36) ..................... 1995-1998
BMW 323ti (E36/5) ..................... 1995-2000
BMW 523i (E39) ..................... 1995-2000
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