BMW S85
| BMW S85 engine | |
|---|---|
 |
|
| Overview | |
| Manufacturer | BMW Bayerische Motoren Werke |
| Production | 2005–2010 |
| Combustion chamber | |
| Configuration | 90° V10, odd-firing |
| Cylinder bore | 92 mm |
| Piston stroke | 75.2 mm |
| Cylinder block alloy | Aluminum–silicon alloy |
| Cylinder head alloy | Aluminum alloy |
| Valvetrain | DOHC, double-VANOS |
| Compression ratio | 12.0:1 |
| Combustion | |
| Fuel system | Fuel injection |
| Management | Siemens MS S65 ECU |
| Fuel type | Gasoline |
| Cooling system | Water-cooled |
| Output | |
| Power output | 373 kilowatts (500 hp) |
| Torque output | 520 N·m (384 lb·ft) |
| Dimensions | |
| Dry weight | 240 kg (529 lb) |
| Chronology | |
| Predecessor | S62 |
| Successor | S63 |
The BMW S85B50 is a DOHC V10 piston engine which replaced the S62 and was produced from 2005-2010. Used in the E60 M5 sedan, E61 M5 touring and E63/64 M6 coupé, it was inspired by BMW's previous Formula 1 involvement.
As the S85 was BMW's first V10 engine, it was given a new series in the nomenclature. While V8 engines are designated by "60s" and V12 engines labeled as "70s", the S85 was badged with an "80" despite it having fewer cylinders than the "70"-series engines.
The S85 spawned a related S65 V8 engine for the 2008 BMW M3. Although the "65" designation is apparently out of order compared to the other V8 engines (which follow "62" and "63" sequentially), the S65 was badged such since its design is largely derived from the S85 minus two cylinders, and not related to BMW's other V8s.
Unlike other BMW engines, there are no mass market "M" or "N" versions of the S85 and S65 and nor are there any shared parts, as these engines are used exclusively in BMW M performance vehicles.
The S85B50 is a high-revving engine designed to utilize power from a wide rev band. Having a redline of 8250 rpm, it achieves over 100 bhp (70 kW)/litre. The S85 features a very high compression ratio of 12.0:1, exceeding the previous S54's ratio of 11.5:1.
It produces over 100 hp more than the previous E39 4.9liter V8, whilst weighing only 2.2 pounds more. The S85 utilizes both individual throttle bodies and Double VANOS (BMW's infinitely variable timing for intake and exhaust cams.
In 2005, the first year that it was nominated, the S85B50 won four different International Engine of the Year awards in the following 4 categories:
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