BMW S85

The BMW S85 is a naturally aspirated V10 petrol engine which replaced the BMW S62 V8 engine in the M5 model and was produced from 2005–2010. It was both BMW's first and only production V10 engine, and the first petrol V10 engine to be available in a production sedan (saloon).

BMW S85 engine
Overview
Production2005–2010
Layout
Configuration90° V10
Displacement5.0 L (305 cu in)
Block materialAluminium
Head materialAluminium
ValvetrainDOHC w/ VVT
Combustion
Fuel typePetrol
Chronology
PredecessorNone
SuccessorNone

Introduced in the E60 M5, the S85 was inspired by BMW's previous Formula One involvement.[1] Unlike most other BMW M engines, the S85 is not related to a regular production BMW engine.[2]

The BMW S65 V8 engine (used in the E92 M3) is based on the S85.

Nomenclature

As the S85 was BMW's first V10 engine, it was given a new series in the BMW's engine codes. The "60s" were used for V8 engines and the "70s" were used for V12 engines, therefore the V10 was allocated in the "80s" (despite having fewer cylinders than the V12 engines in the "70s".

The engine code for the related BMW S65 V8 engine reflects its link to the S85. The S65 code was selected to signify that the V8 is largely derived from the S85 minus two cylinders, and not related to BMW's other V8s.[3]

Design
VersionYearDisplacementPowerTorque
S85B502005–20104,999 cc (305.1 cu in)373 kW (500 bhp)
at 7,500 rpm		520 N⋅m (384 lb⋅ft)
at 6,100 rpm

The S85 has dual overhead camshafts with four valves per cylinder and double-VANOS (variable valve timing).[4] The engine block and cylinder head are constructed from aluminum alloy.[5]

Peak power is 373 kW (500 bhp) at 7,750 rpm and peak torque is 520 N⋅m (384 lb⋅ft) at 6,100 rpm.[6] The redline is 8,250 rpm,[2] and the specific output of 74.6 kW (100.0 bhp) per litre is amongst the highest of naturally aspirated production car engines.

Features include:

  • Displacement of 4,999 cc (305.1 cu in)[6]
  • Compression ratio of 12.0:1[7]
  • Bore of 92 mm (3.62 in) and stroke of 75.2 mm (2.96 in)[6]
  • 10 electronically actuated individual throttle bodies[8]
  • Cast aluminum block with bed plate design[9] split at the crankshaft axis
  • Valves actuated through non-rotating inverted bucket cam followers
  • Oil-cooled, cast aluminium pistons
  • Forged steel crankshaft with counterweights, shared crankpins producing an uneven firing interval of 90 or 54 degrees
  • Siemens MS S65 engine control unit
  • Application of an "ionic current measuring system" for knock sensing.[10] The ionic current system uses a low voltage applied across the spark plugs immediately following the ignition spark, and can detect misfires as well as pre-ignition ("knocking").
  • Quasi-dry sump lubricating system where the engine has 2 oil sumps that hold oil, and oil pickup is enhanced by secondary electrical scavenge pumps that feed oil from the smaller sump to the main sump[11]
  • Firing order of 1-6-5-10-2-7-3-8-4-9
  • Mass of 240 kg (529 lb)[12]

Awards

The S85 has won the following awards at the International Engine of the Year:[13]

  • 2005 International Engine of the Year, Best Performance Engine, Best Above 4.0 Litre, Best New Engine
  • 2006 International Engine of the Year, Best Performance Engine, Best Above 4.0 Litre
  • 2007 Best Performance Engine, Best Above 4.0 Litre
  • 2008 Best Above 4.0 Litre

Applications

References
  1. "BMW M5 - 2004 Geneva Auto Show". Insideline.com. 15 May 2007. Archived from the original on 12 June 2012.
  2. "2006 BMW M5 - First Drive Review". www.caranddriver.com. Retrieved 23 February 2012.
  3. "FAQ - E90 + E92 + E93 M3". www.bmwmregistry.com. Retrieved 21 July 2017.
  4. "2006 BMW M5 review". www.roadandtrack.com. Retrieved 25 July 2017.
  5. "BMW S85 engine reliability, problems and repair". mywikimotors.com. Retrieved 25 July 2017.
  6. "BMW M5 Sedan Engine and Chassis Technical Data". BMW AG. Archived from the original on 12 August 2008. Retrieved 4 July 2017.
  7. "BMW S85 V10 and S65 V8 Engines". www.unixnerd.demon.co.uk. Retrieved 28 July 2017.
  8. "BMW Retires the M6 & The Mighty S85 V10". www.bimmerfile.com. Retrieved 4 July 2017.
  9. "BMW's new V10 engine in detail". www.newatlas.com. Retrieved 25 July 2017.
  10. "BMW S85 engine". www.australiancar.reviews. Retrieved 25 July 2017.
  11. http://www.mwerks.com/artman/publish/features/article_594.shtml?page=2
  12. "Review: BMW E60 LCI M5 (2007-10)". www.ukcar.reviews. Archived from the original on 30 March 2018. Retrieved 25 July 2017.
  13. "International Engine of the Year - Archive". www.ukimediaevents.com. Retrieved 28 July 2017.
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