|Predecessor||BMW OHV V8|
|Engine(s)||3.0 L (2997 cc/182 in³)|
4.0 L (3982 cc/242 in³)
|M60B30||3.0 L (2997 cc/182 in³)||160 kW (215 hp) @ 5800||290 N·m (214 ft·lbf) @ 4500||6500||1992|
|M60B40||4.0 L (3982 cc/242 in³)||210 kW (282 hp) @ 5800||400 N·m (295 ft·lbf) @ 4500||6500||1992|
Design made extensive use of CAD to minimize size and weight. It had a closed-deck cylinder block for maximum rigidity, and used aluminum alloy for both block and cylinder head. The valve covers were magnesium, and the intake manifold was nylon. Nikasil plating was used rather than iron for the cylinder liners (although this proved problematic, as described below). The sintered connecting rods were made as a single piece and then fractured in order to ensure a closer fit. The block weighed 55 lb (25 kg), and the heads 65 lb (29 kg) each. Total dry weight was 447 lb (203 kg).
The M60 engine had four valves per cylinder, with chain-driven dual overhead camshafts. Valves had hydraulic lash adjustment to reduce maintenance, and the camshaft chain drive was self-adjusting. There was no distributor, each cylinder having its own ignition coil. Fuel injection and ignition were managed by the Bosch DME (Digital Motor Electronics) 3.3 computer system.
The M60 was offered in two sizes: the 3.0 L (183 in³) M60B30 and the 4.0 L (243 in³) M60B40. The two had very similar design, but neither block, heads, nor crankshaft were interchangeable.
The M60B30 had a bore of 84 mm (3.31 in) and a stroke of 67.6 mm (2.66 in), for a displacement of 2,997 cc (183 in³). Compression ratio was 10.5:1, giving an output of 218 hp (163 kW) @ 5800 rpm and 210 ft·lbf (290 N·m) @ 4500 rpm.
Cars with this engine:
The M60B40 had a bore of 89 mm (3.50 in) and a stroke of 80 mm (3.15 in), for a total displacement of 3,982 cc (243 in³). Compression was 10.0:1, giving 286 hp (213 kW) @ 5800 rpm and 295 ft·lbf (400 N·m) @ 4500 rpm. It had a forged crankshaft rather than the M60B30's cast piece.
Cars with this engine:
The Nikasil problem
BMW used Nikasil, an aluminium, nickel, and silicon alloy, to line the cylinders of the M60 engines. The cross-hatched Nikasil linings react with the high sulfur content found in lower-quality gasoline, such as that used in parts of the United States. This reaction causes damage to the very top of the cylinder bore, where there is the most contact of the burning mixture and the cylinder lining. The damage prevents a good seal from forming between the piston and the cylinder wall, causing a loss of compression in the combustion chamber. This "leak down" will cause M60s with worn linings to exhibit a rough idle, and if the problem continues unchecked, the engine will not start.
The only permanent fix for this problem is the replacement of the short block with the equivalent block composed of Alusil, which do not exhibit this corrosion problem. After the problem was found, BMW issued an extended six-year, 100,000-mile (160,000 km) warranty to cover these engines at no cost to the owner.
The composition of the engine can be found by checking the serial number stamped into the engine block:
- 1 725 970 - Nikasil
- 1 741 212 - Nikasil
- 1 745 871 - Alusil
- 1 725 963 - Nikasil
- 1 742 998 - Nikasil
- 1 745 872 - Alusil