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The 'BMW M30' is an inline-6 cylinder engine built by BMW and was once used in all of its six cylinder cars. It was originally developed in the late 1960s as an extended 2.5 liter version of the robust inline four cylinder BMW M10 first used in the 'Neue Klasse' BMW 1500, with which it shares a number of design features, including a 30-degree cant to the right for a lower profile, a crossflow head design, and a chain-driven single overhead cam with rocker arm valve actuation. The 'Big Six' (also known as the 'Senior Six') got its informal names after the introduction of a smaller BMW M20 belt-driven SOHC six cylinder in the late '70s.
The M30 powered a series of BMW 6-cylinder E9 and BMW E24 coupes to European touring car championships (ETCC) throughout the '70s and into the middle 1980s, even though a more powerful DOHC 24-valve head had been developed for high performance motorsports and street use.
A production turbo variant of the M30 designated the M102B32 or M102B35 (depending on 3.2 or 3.4 liter displacement) was used in the BMW E23 Seven Series where it was designated "745i", based on a then-current projection that the horsepower produced was roughly equal to that of a 4.5 liter normally-aspirated engine. The 3.5 DOHC M5 and M6 engine was used in the South African 745i from 1984-1986.
BMW's M30 straight six cylinder engines had the longest production run of any BMW engine, dating back to the 1968 E3 sedans and E9 coupes. The last use of the block was the 1994 E32 730i. Displacement ranged from 2.5 to 3.4 liters with a 100 mm bore spacing.
The M30 engine's bottom end is virtually 'bulletproof' and a true workhorse. The M30's timing chain is designed to last the life of the engine and it will, if the timing chain tensioner is maintained. Unfortunately, over time and use, the plastic parts in it can fail but they are easily replaced. The alloy head is prone to warping if the engine is overheated (especially around the somewhat restricted cooling system passages near the middle), but with regular cooling system maintenance, oil changes, and other routine maintenance, the M30 can routinely run well past 250,000 miles.
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'Models'

Engine	Displacement	Power	Torque	Redline	Year
M30B25	2.5 L (2494 cc/152 in³)	110 kW (147 hp) @ 5500	215 N·m (158 ft·lbf) @ 4000		1981
		110 kW (147 hp) @ 5500	215 N·m (158 ft·lbf) @ 4000		1981
M30B28LE	2.7 L (2788 cc/170 in³)	135 kW (181 hp) @ 5800	240 N·m (177 ft·lbf) @ 4200		1979
		135 kW (181 hp) @ 5800	240 N·m (177 ft·lbf) @ 4200		1979
M30B30	2.9 L (2986 cc/182 in³)	135 kW (181 hp) @ 5800	255 N·m (188 ft·lbf) @ 3500		1976
		135 kW (181 hp) @ 5800	255 N·m (188 ft·lbf) @ 3500		1976
		138 kW (185 hp) @ 5800	260 N·m (191 ft·lbf) @ 4000		1986
		138 kW (185 hp) @ 5800	260 N·m (191 ft·lbf) @ 4000		1986
M30B32	3.2 L (3210 cc/195 in³)	145 kW (194 hp) @ 5500	285 N·m (210 ft·lbf) @ 4300		1979
		145 kW (194 hp) @ 5500	285 N·m (210 ft·lbf) @ 4300		1979
M30B32LAE		185 kW (248 hp) @ 5200	380 N·m (280 ft·lbf) @ 2600		1980
		185 kW (248 hp) @ 5200	380 N·m (280 ft·lbf) @ 2600		1980
M30B32LE		145 kW (194 hp) @ 5500	280 N·m (206 ft·lbf) @ 4300		1976
		145 kW (194 hp) @ 5500	280 N·m (206 ft·lbf) @ 4300		1976
M30B34	3.4 L (3430 cc/209 in³)	155 kW (207 hp) @ 5700	305 N·m (224 ft·lbf) @ 4000	6200	1986
		155 kW (207 hp) @ 5700	305 N·m (224 ft·lbf) @ 4000	6200	1986
M30B34M		136 kW (182 hp) @ 5400	290 N·m (213 ft·lbf) @ 4000		1984
		160 kW (214 hp) @ 5500	310 N·m (228 ft·lbf) @ 4000		1982
		136 kW (182 hp) @ 5400	290 N·m (213 ft·lbf) @ 4000		1984
		160 kW (214 hp) @ 5500	310 N·m (228 ft·lbf) @ 4000		1982
M30B34MAE		185 kW (248 hp) @ 4900	380 N·m (280 ft·lbf) @ 2200		1982
		185 kW (248 hp) @ 4900	380 N·m (280 ft·lbf) @ 2200		1982

2.8 L (2788 cc) Applications:

★ 1979-1987 E24 628CSi
3.0 L (2986 cc) Applications:

★ 1976-1979 E24 630CS
3.2 L (3210 cc) Applications:

★ 1976-1984 E24 633CSi
3.4 L (3430 cc)
Applications:

★ 1983-1993 Europe

★ 1985-1993 US
3.5 L (3453 cc) Applications:

★ 1978-1983 E24 635CSi
3.5 L (3453 cc) DOHC Applications:

★ 1987-1989 E24 M6

★ 1984-1988 M635csi/M6

★ 1984-1986 745i - South Africa

Contents

M30B30

M30B34

M30B35

See also

M30B30

Introduced in 1986 with the E32, the 2.9 L (2986 cc) 'M30B30' produced 185 hp. The engine continued in production until 1994.
Applications:

★ 1986-1994 E32 7-Series

★ 1988-1993 E34 5-Series

M30B34

3.4 L
Applications:

★ 1985-1988 E28 5-Series

★ 1985-1987 E24 6-Series

★ 1985-1987 E23 7-Series

M30B35

★ 3.4 liter (3430 cc) SOHC inline-6 cylinder

★ 9.0:1 compression ratio

★ 208 hp @ 5700 rpm

★ 225 ft·lbf torque @ 4000 rpm

★ 89 Octane fuel or better recommended
Applications:

★ 1988-1989 E24 635CSi

★ 1988-1993 E34 535i

★ 1988-1992 E32 735i

See also