# Basic engine information

#### Identifying your engine.

M10 and S14 have the engine number located on the transmission mating surface, on the left side, just above the starter motor. There is also an engine code in the same place

M20 has both numbers located below the oil pump drive shaft access point, left side of the engine just behind the power steering pump.

M42 has the engine number and code located on the left rear of the block at the oil pan mounting surface.

In all cases, the engine number consists of two groups of 4 numbers. e.g. 1234 5678 and the engine code consists of 5 digits.

The first number of the first group is the engine ID. 0 or 1 = M10 or M42, 2 or 3 = M20, 6 = S14
Next 3 numbers represent a unique serial number
First number of the second group is the plant code. 0 - 4 for Munich , 5 - 9 for Steyr
The last 3 numbers of the second group are the production day (Julian date).

The engine number for new or remanufactured consists of 2 groups of 4 numbers like the production versions, but the meaning is different.

The first 4 numbers are a sequential serial number
Next is code A for remanufactured, or N for new engine.
Next two are month, last digit is the last digit of the year.

The first two digits of an engine code give the engine capacity in liters, e.g. 27 = 2.7 Liter. Next number is amount of cylinders, next letter is E for injection, V for carburetor, T for turbocharged, S for sequential fuel injection or K for Catalyst. Final letter is either an internal BMW code, or a country code.

Engine codes are as follows :

318i | M10B18 | 18 4K A | 101 hp
318i | M42B18 | 18 4S 1 | 134 hp
325e 1984 - 1986 | M20B27 | 27 6K A | 121 hp
325e 1987 | M20B27 | 27 6K B | 128 hp
325i (all years) | M20B25 | 25 6K 1 | 168 hp
M3 | S14B23 | 23 4E A | 192 hp

##### Engine

##### M10B18

##### S14B23

##### M42B18

##### M20B25

##### M20B27 (pre 88)

##### M20B27 (from 88)

##### Cylinders

4

4

4

6

6

6

##### Stroke

84mm (3.307")

81mm

75mm

81mm

81mm

##### Bore

93.4mm (3.677")

84mm

84mm

84mm

84mm

##### Displacement

2302 cc

1796 cc

2494 cc

2693 cc

2693 cc

##### Compression ratio

10.5:1

10:1

8.8:1

9.0:1

8.5:1

##### Combustion chamber volume

43.0 ± 0.5 cc

40.2 ± 1 cc

##### Compression pressure

14 bar

10 - 11 bar

10 - 11 bar

##### Camshaft duration

248°

240°

##### Intake valve diameter

37mm

33mm

42mm

##### Exhaust valve diameter

32mm

30.5mm

36mm

##### Valve clearance (cold)

0.28 - 0.33mm

Non adjustable

0.25mm

##### Oil pressure at max rpm

4.0 - 5.0 bar

4.0 bar

4.0 - 5.0 bar

##### Oil capacity

4.65 liter +0.3 for new filter

4.5 liter + 0.36 for new filter

4.75 liter +0.75 for new filter

##### Thermostat

80° C

88° C

80° C

##### Firing order

1-3-4-2

1-3-4-2

1-3-4-2

1-5-3-6-2-4

1-5-3-6-2-4

1-5-3-6-2-4

##### Spark plugs

Bosch X5DC

Bosch W8LCR

##### Plug gap

0.6 + 0.1mm

0.9mm

0.7 + 0.1mm

##### Power

192hp/143kW @ 6750 rpm

134hp/100kW @ 6000rpm

168hp/123kW @ 5800 rpm

121hp/90kW @ 4250 rpm

127hp/95kW

##### Torque

169 ft/lbs. / 230 Nm @ 4750 rpm

127 ft/lbs. / 172 Nm @ 4600 rpm

164 ft/lbs. / 222 Nm @ 4300 rpm

170ft/lbs. / 230 Nm @ 3250 rpm

171 ft/lbs. / 230 Nm

##### Idle speed

880 ± 50 rpm

850 ± 40 rpm

760 ± 40 rpm

##### Max engine speed

7240 ± 80 rpm

6500 ± 40 rpm

6400 ± 80 rpm

##### Max sustained engine speed

6900 rpm

##### Required fuel

87 AKI (91 RON)

93 AKI

90 AKI (96 RON)

87 AKI (91 RON)

87 AKI (91 RON)

E30 M3 Repair Manual V2.7. Copyright ©1999-2001 Koala Motorsport & Brett Anderson