First Generation M30 (78-82) Bore and Stroke: 84 x 93.4,  218 Hp
The 3.5 liter M30 engines of this era were available in two totally different versions. The first example came out in 1978 in the 6-Series, it had the same bore and stroke as the M engine: 93.4 mm bore and 84 mm stroke. This model was used until 1982. It put out 218 Hp and 310 Nm of torque. In these early engines, individual intake tubes were used, as was the L-Jetronic (as seen in the top picture below). The intake had multiple parts, and thus could be easily taken apart and worked on. This was later replaced with a one-piece intake, cast of aluminum (represented in the lower picture below). The updated version also had the first generation Motronic computer.

  Here you see the straight intake

Later replaced with a one-piece unit          

Second Generation M30 (82-87) Bore and Stroke: 86x92, 185/218 Hp
This version of the M30 had a 92 mm stroke and a bore of 86 mm. This change was inspired by excessive cylinder head seal damage in the early versions of the M30. In nearly every test of the new M30 it was said that it had lost some of its bite. This was in addition to the improved economy of the new M30. It was said, "An engine setup like this simply gets less air, and has consequently lost some of the "punch" of the early versions."  (Oldtimer-Markt 5/94 S.37)   

This engine is easily recognized by the two supports that run from the valve cover to the intake manifold. This version of the M30 originally came in the e23, e24, e28.  Without a catalytic converter it put out 218 Hp and 315 Nm of torque. With a Cat. the output dropped to 185 Hp, due to the restraints applied by the anti-pollution equipment.  This engine is still suitable for making a 335i.  The flatter pistons produce a slightly lower compression ratio, which makes it a good candidate for turbo-charging.

Third Generation M30 (87-92) Bore and Stroke: 86x92, 211/220 Hp
This generation of the M30 was installed in the e32 and e34.  It put out 220 unrestricted Hp and 320 Nm of torque.  Those with a Cat. produced 211 Hp. It is found far more frequently with the Cat.  This version, like the first generation, has the punch expected of such an engine, even with the Cat.  This version represents the most modern version of the M30. This new version differs from its predecessors in the following ways:

• Improved Aesthetics: Plastic Cover on AFM and More Attractive Air Box
• Wiring Harness; Round Engine Plug
• New Exhaust System
• Switch to Motronic 1.1
• 1 mm Larger intake valves
• Increased Compression Ratio
• Coolant Entrance Moved From Rear to Front of Cylinder Head
• Less Play in Connecting Rod Bearings: Less Noise, Worse Performance

Gear Ratios 535i 635CSi 735i
The 5 speed e28 535i received a 3.25:1 rear axle ratio, the automatic got a 3.45:1. The early generation e24 635CSi with L-Jetronic had a 3.07:1 rear axle ratio, the later version, with Motronic and the 3430ccm engine, received a 3.08:1 rear axle ratio, and with the 211 Hp version with a Cat. a 3.64:1 rear axle ratio was used. The e23 invariably had a 3.25:1 rear axle gear ratio, no matter what version of the engine or which transmission it had.

The e28 and e23 manual transmissions had the following gearing:

                  I. 3.822
                  II. 2.199  (2.202: 82-87)
                  III. 1.398
                  IV. 1.000
                  V. 0.813

For the e23, e24 and e28 5 speed "sport"  transmissions the following gearing was used:

                  I. 3.717
                  II. 2.403
                  III. 1.766
                  IV. 1.263
                  V. 1.000

The e24 received the "sport" transmission in 1978, and the other transmission starting in 9/79.

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