M5x

The BMW M5x range of engines are a line of 6-cylinder engines, fitted to BMW models between 1991 and 2001. The range is comprised of two main units; the M50 and the M52. All M5x engines are fundamentally based on the M20 engine that powered the E30 320i, 323i and 325i, and are therefore very popular engine swaps.

Versions

M50

The M50 engine first saw action under the bonnet of the E34 ad E36 as the humble 2.0 variant before being enlarged to 2.5 in 1993. Being little more than an M20 engine with a 24V head, these engines are great upgrades for those who have tired of the M20 donk. Considering there is no difference when installing, there is little or no point fitting the weaker 2.0 version of the M50.

Engine	Displacement	Power	Torque	Redline	Bore	Stroke	Year
M50B20	2.0 L (1990 cc/121 in³)	110 kW (150 hp) @ 6000	190 N·m (140 ft·lbf) @ 4700	6750	80mm	66mm	1991
M50B25	2.5 L (2494 cc/152 in³)	141 kW (192 hp) @ 6000	245 N·m (181 ft·lbf) @ 4700	6500	84mm	75mm	1991

M50TU

After letting the M50 prove itself, BMW released a Technical Update for the engine in 1993, announcing the new engine as the M50TU. These units featured an even more complex head design incorporating VANOS technology; a variable-valve timing system that modifies the position of the intake camshaft. This has no effect on the overall power of the engine, but does improve torque at lower revs.

Because of this increased complexity, VANOS engines are best avoided for first-time engine swappers.

Engine	Displacement	Power	Torque	Redline	Bore	Stroke	Year
M50TUB20	2.0 L (1990 cc/121 in³)	110 kW (150 hp) @ 5900	190 N·m (140 ft·lbf) @ 4700	6750	80mm	66mm	1993
M50TUB25	2.5 L (2494 cc/152 in³)	141 kW (192 hp) @ 5900	250 N·m (184 ft·lbf) @ 4200	6500	84mm	75mm	1993

M52

The M52 brought two new things to the BMW range of engines. Dual-VANOS, and Nikasil.

Engine	Displacement	Power	Torque	Redline	Bore	Stroke	Year
M52B20	2.0 L (1990 cc/121 in³)	110 kW (148 hp) @ 5900	190 N·m (140 ft·lbf) @ 4700	6500	80mm	66mm	1994
M52B25	2.5 L (2494 cc/152 in³)	123 kW (170 hp) @ 5500	245 N·m (181 ft·lbf) @ 3950	6500	84mm	75mm	1995
M52B28	2.8 L (2793 cc/170 in³)	142 kW (193 hp) @ 5300	280 N·m (207 ft·lbf) @ 3950	6500	84mm	84mm	1995

S50

Engine	Displacement	Power	Torque	Redline	Bore	Stroke	Year
S50B30	3.0 L (2990 cc/182 in³)	210 kW (286 hp) @ 7000	320 N·m (235 ft·lbf) @ 3600	7280	86mm	85.8mm	1992
S50B32	3.2 L (3201 cc/195 in³)	236 kW (321 hp) @ 7400	350 N·m (257 ft·lbf) @ 3250	7600	86.4mm	91mm	1995

Components

VANOS

Rocker Cover

Despite the three styles of Head, the rocker cover is interchangeable across all M40 engines. It is positioned on 8 studs and fixed with M10 nuts. It has one hole for the Oil Cap, and one port for the breather hose.

When removing and replacing the rocker cover, it is worth replacing the rocker cover gasket.

Breather Hose

To balance the pressure inside the head, a rubber hose runs from the top of the rocker cover to the throttle body.

Servicing

Main article: Basic M5x Servicing

See also

• Engines
• M10
• M42