BMW M50

BMW M50 engine
Overview
Manufacturer	BMW
Production	1989–1994
Body and chassis
Class	Straight-6
Chronology
Predecessor	BMW M20
Successor	BMW M52

The BMW M50 is an I6 piston engine. It was introduced in March 1989 to replace the BMW M20 and was replaced by the BMW M52 in 1994. Displacement ranges from 2.0 L to 3.2 L. It is a DOHC 24-valve engine. A Technical Update or M50TU version from 1992 introduced VANOS variable valve timing.

The M50 was related to the M20 with the same 91 mm cylinder spacing, bore, and stroke at 2.0 L and 2.5 L.

Models

Engine	Displacement	Power	Torque	Redline	Year
M50B20	2.0 L (1991 cc/121 in³)	110 kW (148 hp) @ 5900	190 N·m (140 ft·lbf) @ 4700	6500	1989
M50B24	2.4 L	110 kW (148 hp) @ 5900
M50B25	2.5 L (2494 cc/152 in³)	141 kW (189 hp) @ 5900	245 N·m (181 ft·lbf) @ 4700	6500	1989
		141 kW (189 hp) @ 5900	250 N·m (184 ft·lbf) @ 4200	6500	1992
		141 kW (189 hp) @ 5900	245 N·m (181 ft·lbf) @ 4200	6500	1992

M50B20

The 2.0 L (1991 cc) M50B20 was introduced with the 1989 520i. It has an 80 mm bore and 66 mm stroke and produces 150 hp (110 kW).

Applications:

• 1990-1995 E36 320i
• 1989-1995 E34 520i

M50B24

This is a 2.4 L engine based on the 2.5 L M50B25, with a reduced stroke. This engine is only fitted to CKD kits assembled in Thailand. Power output is 188 hp (140 kW) and torque is 177 ft.lbf (240 Nm).

Applications:

• 1993-1997 E36 3-Series (Thai specification)
• 1993-1997 E34 5-Series (Thai specification)

M50B25

The 2.5 L (2494 cc) M50B25 was introduced with the 1991 325i. It has an 84 mm bore and 75 mm stroke and produces 189 hp (141 kW).

Applications:

• 1991-1995 E36 325i
• 1992-1995 E34 525i/525ix

Note: This is the engine from which the M50TU evolved. The VANOS update was added late 1992 and sold for 1993 model year E34s. The M50 has a Compression_ratio of 10:1, and the M50TU of 10.5:1

M52B28

Updated version of the m50, utilizing a larger stroke to reach 2.8 liters and also a revised intake manifold. Also ECU was changed to an OBD2 type vs. the previous OBD1. These engines also featured vanos variable valve timing, as did some of the previous m50 engines.

Applications:

• 1996-2001 [BMW e36 and e46 328i]
• 1996-2000 [BMW e39 528i]

S50B30US

The S50B30US was a 3.0 L version, which powered the US-spec E36 M3. Power was 240 hp (179 kW).

Applications:

• 1995 E36 M3

S50B30

The S50B30 was a special sports-oriented 3.0 L version, which powered the RoW spec E36 M3. Power is 286 hp (210 kW). The S50B30 has a bore of 86mm and a stroke of 85.8mm, with a total displacement of 2990cc.

Applications:

• 1992-1995 E36 M3

S50B32

The S50B32 was an evolution version of the S50B30. Power of the 3.2 L version is 321hp. This engine has a bore of 86.4mm and a stroke of 91.0mm giving a displacement of 3201cc.

Applications:

• 1996-1999 E36 M3
• 1997-2000 M Roadster
• 1998-2000 M Coupe

S54B32

The S54 was a redesigned s52 engine retaining the same displacement but yielding much more power than the previous models a 333 hp in US spec. This is the premier performing engine in the m50 line with a 8000 rpm redline, individual throttle bodies, drive by wire throttle, and double variable valve timing.

Applications:

• 2001-2006 [BMW E46 M3]
• 2000-2002 [BMW Z3 M Roadster]
• 2001-2002 [BMW Z3 M Coupe]
• 2006-current [BMW Z4 M Roadster]
• 2006-current [BMW z4 M Coupe]