BMW S85

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BMW S85 engine
BMW S85B50 Engine.JPG
Overview
Manufacturer BMW
Production 2005–2010
Combustion chamber
Configuration DOHC 90° V10
Chronology
Predecessor S62
Successor S63

The BMW S85 (also known as S85B50) is a naturally aspirated V10 petrol engine which replaced the V8 S62 and was produced from 2005-2010. It was BMW's first ever production V10, and the first petrol V10 engine to be available in a production sedan.

Used in the E60 M5 sedan, E61 M5 touring and E63/64 M6 coupé, it was inspired by BMW's previous Formula 1 involvement.[1] Unlike most other "S" series engines, the S85 is not related to a regular production ("M" or "N") BMW engine.[2]

The S65 V8 engine is based on the S85.

Nomenclature[edit]

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 S65 V8 engine reflects its link to the S85. Compared with the sequence for regular engines at the time (N62 and N63), the S65 V8 is out of order. However, the code S65 was chosen to reflect that the V8 is largely derived from the S85 minus two cylinders, and not related to BMW's other V8s.[3]

Design[edit]

The S85 has dual overhead camshafts with 4 valves per cylinder and variable valve timing on the intake and exhaust camshafts (double-VANOS). The engine block and cylinder head are constructed from Aluminum alloy.[4]

Peak power is 373 kW (507 PS; 500 bhp) at 7750 rpm and peak torque is 520 N·m (384 lb·ft) at 6100 rpm.[5] The redline is 8200 rpm,[6] and the specific output of over 100 bhp (70 kW) per litre is amongst the highest of naturally aspirated production car engines.

Features include:

  • Compression ratio of 12.0:1[7]
  • Bore is 92 mm (3.6 in) and stroke is 75.2 mm (3.0 in).
  • 10 electronically actuated individual throttle bodies[8]
  • Cast aluminum block with bed plate design[9] split at the crankshaft axis.
  • Valves are actuated through non-rotating inverted bucket cam followers.
  • Oil-cooled, cast aluminum pistons from Mahle Motorsport.
  • Forged steel crankshaft with counterweights, shared crankpins producing an uneven firing interval of 90 or 54 degrees.
  • Double VANOS system which varies both intake and exhaust cam phasing
  • Siemens MS S65 engine management
  • Knock sensors have been eliminated by utilizing the "ionic current" measuring system.[10] Using the ionic current system, engine misfires as well as knock can be measured simultaneously. The ionic current is measured by passing a low voltage across the spark plugs immediately following the ignition spark.
  • 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 is 1-6-5-10-2-7-3-8-4-9.
  • Weight is 240 kg (529 lb).[12]

Awards[edit]

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[edit]

See also[edit]

References[edit]

  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". Car and Driver. Retrieved 23 February 2012. 
  3. ^ "FAQ - E90 + E92 + E93 M3". www.bmwmregistry.com. Retrieved 21 July 2017. 
  4. ^ "BMW S85 engine reliability, problems and repair". mywikimotors.com. Retrieved 25 July 2017. 
  5. ^ "BMW M5 Sedan Engine and Chassis Technical Data". BMW AG. Archived from the original on 12 August 2008. Retrieved 4 July 2017. 
  6. ^ "2006 BMW M5 review". www.roadandtrack.com. Retrieved 25 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". ww.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. Retrieved 25 July 2017. 
  13. ^ "International Engine of the Year - Archive". www.ukimediaevents.com. Retrieved 28 July 2017.