BMW 5 Series - E28

The BMW E28 was the basis for the 1981 through 1988 BMW 5-Series automobiles. It replaced the BMW E12 in 1981 and was replaced by the BMW E34 in 1989. The E28 was the first 5-Series which BMW offered in an M version.

E28 Engines

The baby six motor found in the 520i, 525e and 528e models is known as the M20, a 12 valve SOHC inline six cylinder design. It had seven main bearings and seven cam shaft bearings, a rocker arm type valvetrain driven by a composite rubber timing belt. US market M20's came with cast aluminum acoustically tuned, common plenum intake manifolds and a single throttle body. This motor was first available in the European market for model year 1976 in a 2.0 L carbureted version. It later grew to 2.3 L in the E21 323i, then 2.5 L in the E30 325i and also 2.7 L in the 325e and 528e models. It is also very similar to the later 24 valve motors as in the E36 and E46 3 series models, with the same basic block dimensions.

The big six motor found in the 528i, 533i and 535i/is models is known as the M30. The M30 is also a 12 valve SOHC inline six cylinder design. It has seven main bearings, four camshaft bearings and a rocker arm type valvetrain. US M30's also came equipped with cast aluminum acoustically tuned common plenum intake manifolds and single throttle bodies. Unlike the M20 it has a chain-driven valvetrain. Its larger dimensions allow for a longer stroke and larger bore, which makes for almost 3.5 L displacement in later motors.

It should be noted that both 533i and 535i M30 intake manifold from 1982-1988 had a "3.2/3.5" casting. During the new intake manifold's development a 3.2 L version existed in Europe and the US, and a 3.5 L in Europe. When the 3.4 L versions came out a year later in Europe, the casting was not changed. The 3.4 L was introduced to the US in 1985. 1988, was the last year this manifold casting was used in the E28 535i and 535is. A new style intake manifold was designed for the new 3.4 L. The casting read "3.5", but it was still 3.4 L (3430 cc). For the US, the 735i and the 635 csi were the first to receive the new M30 in 1988.

The M5 came with a big six motor known as the "S38". This motor is similar to the M30, but has a 24 valve cylinder head, duplex timing chain, dual overhead cam layout and shim and bucket style valvetrain. In addition to the top end revisions, the S38 also had six individual throttle bodies and intake trumpets fed by a cast aluminum intake plenum. This motor was designed for high power and durability at very high engine speeds. In the E28 chassis it was one of the fastest sedans in the world for its time, and it remains legendary among enthusiasts today.

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