June 25, 2024
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The Legendary Senior Six: BMW’s M30 Engine

The BMW M30 is a six-cylinder gasoline engine, known for being the longest-produced engine for approximately 27 years. From 1968 to 1995, the BMW M30 engine powered various BMW vehicles.

This inline-six engine made its debut in the BMW 2500 and 2800 sedans. Initially, the M30 came in 2.5 liters & 2.8 liters or 2,494 cc & 2,788 cc respectively. Over time, engineers developed larger displacements, with the largest being 3.5 liters (3,430 cc).

BMW is renowned for producing top-notch inline-six engines, and the M30 is no exception to this German engineering prowess. The M30 was a robust and powerful engine, earning the title of one of the “Top Engines of the 20th Century” by Ward’s.

With its exceptional reliability and performance, the BMW M30 dominated the market for nearly three decades, leaving behind a legacy for others to follow.

BMW M30: An Overview

The BMW M30 engine was developed in the 1960s based on the BMW M10 four-cylinder engine. The M30 engine featured an iron block, aluminum head, and an overhead camshaft with two valves per cylinder.

Sharing similarities with the M10 engine, the M30 also had a profile lowering 30-degree slant to the right, crossflow cylinder head, and a chain-driven camshaft with rocker arm valve actuation.

Often called the “Big Six” and “Senior Six”, the M30 was the most powerful and largest regular production engine until the launch of the BMW M70 V12 engine in 1987.

All The Versions

Credit: autowp.ru

Introduced in 1968, the BMW M30 engine underwent several iterations over the years, each offering improved performance and reliability.

Starting from the 2,494 cc version, the engine evolved up to 3,430 cc. Let’s explore each version for a better understanding.

M30B25V

The M30B25V, introduced in 1968 in the E3 2500, had a displacement of 2,494 cc. With a compression ratio of 9.0:1, it produced approximately 148 bhp at 6000 rpm and a torque of 156 lb-ft at 3,700 rpm.

Equipped with dual Solex Zenith 35/40 INAT carburetors, the M30B25 was previously known as M06 and M68 before being renamed as M30B25V, where the “V” signifies Vergaser (carburetor in German).

Applications:

The M30 was featured in the E3 2500 (1968–1977), E9 2.5 CS (1974–1975), E12 525 (1973–1976), E12 525 (1976–1981), and E23 725 (1977–1979).

M30B25

The M30B25, introduced in 1981, maintained the 2,494 cc iteration but utilized Bosch L-Jetronic electronic fuel injection. This upgrade resulted in a peak power of 148 bhp at 6000 rpm and a slightly increased torque of 159 lb-ft at 3,700 rpm.

Applications:

The M30B25 was utilized in the E28 525i (1981-1987) and E23 725i (1981-1986).

M30B28V

The M30B28V, introduced in 1968 alongside its lower-powered counterpart M30B25V, employed two Solex Zenith “35/40 INAT” carburetors, leading to the “V” designation in its name.

Featuring a displacement of 2,788 cc, it had a bore of 86 mm and stroke of 80 mm, with a compression ratio of 9.0:1.

Capable of producing around 168 hp at 6,000 rpm and 173 lb-ft at 3,700 rpm, the results could slightly vary based on the model and carburetor used in different countries.

Prior to being named M30B28V, it was previously referred to as M06 and M68.

Applications:

  • E3 2800 (1968-1977)
  • E9 2800 CS (1968-1971)
  • E3 Bavaria (1971-1971) – only for the United States
  • E12 528 (1974-1976) with dual Zenith INAT carburetors
  • E12 528 (1976-1978) with Solex 4A1 carburetor
  • E23 728 (1977-1979) also with Solex 4A1 carburetor

M30B28

In 1977, BMW enhanced the 2,788 cc engine to include Bosch L-Jetronic electronic fuel injection. This upgrade boosted the peak power output to 181 bhp at 5,800 rpm and torque to 177 lb-ft at 4,200 rpm.

Applications:

  • E12 528i (1977-1978) for North American markets only
  • E12 528i (1978-1981)
  • E23 728i (1979-1986)
  • E24 628CSi (1979-1987)
  • E28 528i (1981-1987)

M30B30V

The M30B30V was an upgrade from the M30B28V, featuring a 3 mm larger bore to attain a displacement of 2,986 cc. Equipped with dual Zenith 35/40 INAT carburetors and a compression ratio of 9.0:1, this version delivered a peak power of 178 bhp and 188 lb-ft torque at 3,700 rpm.

However, in the United States, the engine produced 170 hp at 5800 rpm.

Applications:

  • E9 3.0 CS (1971-1975)
  • E9 3.0 CSL (1971-1972)
  • E3 3.0 S / 3.0 L / Bavaria (1971-1974)
  • E24 630 CS (1976-1979) with Pierburg 4A1 carburetor
  • E23 730 (1977-1979) with Solex 4A1 carburetor

M30B30

The 2,986 cc fuel-injected M30 engine was introduced in 1971 with a Bosch D-Jetronic mechanical fuel injection system. In 1976, this unit upgraded to the Bosch L-Jetronic electronic fuel injection system.

Peak output varied depending on the model and year, averaging around 197 bhp at 5,500 rpm and 201 lb-ft torque at 4,300 rpm.

Applications:

  • E9 3.0 CSi (1971-1975)
  • E9 3.0 CSL (1972-1973)
  • E3 3.0 Si (1972-1975)
  • E12 530i (1975-1978) North America only
  • E12 530 MLE (1976-1976) only for the South African market
  • E24 630CSi (1977-1978) Only North America market
  • E32 730i (1986-1995) -185bhp
  • E34 530i (1988-1990) -185bhp
Credit: autowp.ru

M30B32

The M30B32, a 3,210 cc engine often badged as 3.3L, was in production from 1978 to mid-1981. The U.S. version of this engine initially featured Bosch L-Jetronic electronic fuel injection, later transitioning to Bosch Motronic digital fuel injection.

The M30B32 achieved a peak power output of 197 bhp at 5,500 rpm and 210 lb-ft at 3,500 rpm.

Applications:

  • E9 3.0 CSL (1973-1975)
  • E24 633CSi (1976-1984) producing 194 or 197 bhp in Euro spec, and 172–174 bhp in USA spec
  • E3 3.3 Li (1976-1979)
  • E23 733i (1977-1984) producing 197 bhp in Euro spec, 174–194 bhp in USA spec
  • E12 533i (1979-1981) North American market only
  • E23 732i (1979-1986)
  • E28 533i (1982-1984) only North American market
  • E30 333i (1984-1986) only South Africa

M30B33V

The M30B33V, a carburetor version of the engine with a 3,295 cc displacement, was introduced in 1973. Boasting a bore of 89 mm and stroke of 88 mm, this version delivered 187 bhp at 5,500 rpm and torque of 213 lb-ft at 3,500 rpm.

Applications:

This engine powered the E3 3.3 L from 1973-1975.

M30B34

The M30B34, a 3,430 cc engine and the largest displacement in the M30 engine along with the M30B35, was introduced in 1982. With a bore of 92 mm and stroke of 86 mm, this engine featured a compression ratio of 10.0:1 in most markets.

In European and international markets, the engine produced 215 hp at 5,800 rpm and 229 lb-ft at 4,200 rpm. However, North American and Japanese markets received engines with an 8.0:1 compression ratio, generating around 182 hp.

All markets received engines equipped with the Bosch Motronic digital fuel injection system.

Applications:

  • E23 735i / L7 (1982-1987)
  • E24 635CSi / L6 (1982-1987)
  • E28 535i / 535is / M535i (1985-1988)

M30B35

The M30B35, a 3,430 cc engine with the B35 model code, featured Bosch Motronic 1.3 digital fuel injection and a compression ratio of 9.0:1. This version achieved a peak output of around 208 hp at 5700 rpm and 225 lb-ft torque at 4000 rpm.

Certain markets offered this engine without a catalytic converter, resulting in a slightly increased output of 217 hp and 232 lb-ft torque.

Applications:

  • E24 635CSi (1988-1989)
  • E32 735i (1986-1992)
  • E34 535i (1987-1992)

This engine was also employed in the Italian-designed and built luxury off-roader, the Rayton Fissore Magnum 3.5 from 1988-1989.

Special Turbocharged M30 Engine

BMW undertook turbocharging experiments with the M30 engine, leading to the development of special versions. The M30 served as the foundation for BMW’s first turbocharged inline-six engines, which made it the fastest sedan in the world at that time.

BMW M102

The M102, also known as M30B32LAE, was the first turbocharged six-cylinder engine produced from 1980 to 1982.

Featuring a 3,210 cc displacement and a KKK K27 turbocharger delivering 9 psi of boost with an air-to-air intercooler, the engine achieved a peak output of 252 bhp (188 kW). This engine was utilized in the BMW E23 7 Series (“745i”).

BMW M106

The BMW M106, also known as M30B34MAE, succeeded the M102 and was in production from 1982 to 1986.

Featuring upgrades such as Bosch Motronic engine management, the engine boasted a 3,430 cc displacement and increased compression ratio from 7.0:1 to 8.0:1. Despite maintaining a power output of 248 bhp similar to the M102, the peak boost was reduced from 9 to 6 psi.

The M106 did not have a direct successor, but in 2006 BMW introduced the N54 as the next turbocharged petrol engine.

The BMW M106 powered the E23 745i from 1982–1986.

Alpina B10 Bi-Turbo

The Alpina B10 Bi-Turbo was a high-performance variant of the BMW 5 Series E34, launched in 1989 after significant investment. Utilizing a modified M30 engine with two turbochargers and forged pistons, this upgraded engine achieved a peak output of 355 bhp at 6000 rpm and 384 lb-ft at 4000 rpm, making it the fastest sedan of its time.

An interesting fact about this engine is that

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