BMW M30
The BMW M30 is a SOHC straight-six petrol engine which was produced from 1968 to 1995. With a production run of 27 years, it is BMW's longest produced engine and was used in many car models. The first models to use the M30 engine were the BMW 2500 and 2800 sedans. The initial M30 models were produced in displacements of and . Larger displacement versions were introduced over time, with the largest version being , which was sometimes badged as "3.5 litres". As per the BMW M10 four-cylinder engine from which the M30 was developed, the M30  has an iron block, an aluminium head and an overhead camshaft with two valves per cylinder. The engine was given the nicknames of 'Big Six' and 'Senior Six', following the introduction of the smaller BMW M20 straight-six engine in the late 1970s. The M30 was produced alongside the M20 throughout the M20's production, and prior to the introduction of the BMW M70 V12 engine in 1987, the M30 was BMW's most powerful and largest regular production engine. Following the introduction of the BMW M50 engine in 1990, the M30 began to be phased out. Ward's have  rated the M30 as one of the "Top Engines of the 20th Century". Design. The M30 was originally developed in the late 1960s, loosely based on the BMW M10 four-cylinder engine first used in the BMW New Class sedans and coupes. Initially, the engine code was "M06" and the "M68", until all versions began to use the "M30" prefix in 1981. Common features between the M10 and M30 include a profile lowering 30-degree slant to the right, a crossflow cylinder head (a gas flow head in later designs) and chain-driven camshaft with rocker arm valve actuation. Further  similarities include a cast-iron block with an aluminium head and a forged crankshaft. The first two M30 engines introduced were the and the versions, which both used an bore. M30B35LE/M90 engine. The M30B35LE engine, also called the M90, was used in several models from 1979-1982. It combines the block from the motorsports BMW M88 DOHC engine with the M30's SOHC cylinder head. Versions. M30B25V. The first version of the M30 was introduced in the 1968 E3 2500. This version uses dual Solex "Zenith 35/40 INAT" carburettors, has a compression ratio of 9.0:1 and produces in most  applications. It has a bore of and a stroke of . The M30B25 has previously been called the "M06" and "M68", prior to BMW retroactively renaming it the M30B25V (V for "Vergaser"- carburettor in German). Applications: M30B25. In 1981, Bosch L-Jetronic electronic fuel injection was added to the version. Peak power remained unchanged at , however torque increased slightly to . Applications: M30B28V. In its original form, the carburetted 2.8 used two Solex Zenith "35/40 INAT" carburetors, the compression ratio is 9.0:1 and the engine produces and . The specifications went on to vary depending on the model year, carburettor and country. The  bore is and the stroke is . This version has also been known as the "M06" and "M68", prior to BMW renaming it the M30B28V. Applications: M30B28. In 1977, Bosch L-Jetronic electronic fuel injection was added to the version. Power increased to and torque increased to . M30B30V. Based on the M30B28V version with a larger bore, the M30B30V produces and , uses dual Zenith 35/40 INAT carburettors and has a compression ratio of 9.0:1. In United States trim, this engine produced at 5800 rpm. Applications: M30B30. The fuel injected version of the M30 debuted in 1971 in the E9 3.0 CSi  and initially used the Bosch D-Jetronic mechanical fuel injection system. In 1976, the fuel injection system was upgraded to Bosch L-Jetronic electronic fuel injection. The M30B30 produces up to and ,<ref name="TAM74/75"></ref> depending on the model year and whether a catalytic converter is fitted. The compression ratio is 9.2:1. With catalytic converter, compression ratio is 9:1. Applications: M30B32. Despite having a capacity of , this engine appeared in many cars badged so as to suggest of displacement- such as the 633i, 3.3 Li, and 733i. The compression ratio is 8.8:1. In the E24 633CSi coupe, the M30B32  uses Bosch L-Jetronic electronic fuel injection. The US version used L-Jetronic from 1978 until mid-1981, changing over to Motronic digital fuel injection in June of that year. The 1979 732i is BMW's first use of Bosch's Motronic fuel injection. The bore is and the stroke is . Applications: M30B33V. The carburetted M30B33 produces and . It has a bore of and a stroke of . Applications: M30B34. The M30B34 engines sold in Europe and most other markets used a 10.0:1 compression ratio and produced . In North America and Japan, the M30B34 used an 8.0:1 compression ratio and produced . This  engine was also offered in Europe from the latter half of 1985 until mid-1987. In all markets, the Bosch Motronic digital fuel injection system was used. The bore is and the stroke is . Applications: M30B35. This engine has a capacity of , despite the "B35" model code. It produces at 5700 rpm and at 4000 rpm, has a compression ratio of 9.0:1 and uses Bosch Motronic 1.3 digital fuel injection. It was also offered without a catalytic converter for certain markets; this version produces and at the same engine speeds. Applications: Turbocharging. The M30 was the basis for the turbocharged M102  and M106 engines. The Alpina B10 Biturbo used a modified version of the M30, with two turbochargers and forged pistons. Producing at 6000 rpm and at 4000 rpm, the engine made this car the fastest sedan in the world. The final 50 M30 blocks were shipped to Alpina for use in the final 50 B10 Biturbos. M102. The M102 was produced from 1980 to 1982. It was BMW's first turbocharged six-cylinder engine. The M102 (also known as "M30B32LAE") has a displacement of . The KKK K27 turbocharger produces of boost and an air-to-air intercooler is used. The  compression ratio is 7.0:1. The M102 produces and was used in the E23 7 Series, in the model was designated "745i". The M102 was not available in right-hand drive cars, leading to the South African 745i using the BMW M88 naturally aspirated DOHC straight-six engine instead. Applications: M106. The M106 (also called "M30B34MAE") replaced the M102 and was produced from 1982 to 1986. Some of the M106's upgrades over its predecessor are a result of the M30B34 version of the M30, which was also released in 1982. These upgrades include Bosch Motronic engine management and an increased  displacement to . The compression ratio was increased from 7.0:1 to 8.0:1. Peak power output is the same as the M102, however it occurs at lower RPM and peak boost is reduced from . There was no direct successor to the M106, however BMW's next turbocharged petrol engine was the BMW N54, introduced in 2006. Applications: Motorsport. The M30 powered a series of E9 CSL and E24 6 Series coupes to European Touring Car Championship (ETCC) throughout the 1970s and into the middle 1980s, even though a more powerful DOHC 24-valve head had been developed for high-performance motorsports and  street use. The BMW M88 high-performance engine is based on the M30 block.