The BMW S85 B50 A is a 4,999 cc, naturally aspirated V10 petrol engine produced between 2005 and 2010. It features DOHC, 40-valve configuration with individual throttle bodies and double-VANOS variable valve timing. Rated at 373 kW (507 PS) at 8,250 rpm and 520 Nm of torque, this high-revving engine was developed specifically for the E60 M5 and E63 M6.
Fitted exclusively to the E60 M5 and E63 M6, the S85 B50 A was engineered for ultimate driving dynamics and motorsport-derived refinement. Emissions compliance was achieved through close-coupled three-way catalytic converters and secondary air injection system, meeting Euro 4 standards for its production era. Its all-aluminum construction and 90-degree V10 layout provided exceptional smoothness and high-RPM responsiveness.
One documented reliability concern is premature timing chain wear, particularly in early production units before 2007. This issue, referenced in BMW Motorsport Service Information Bulletin 11 03 04, is attributed to inadequate lubrication at the chain tensioner during cold starts. In 2007, BMW revised the oil gallery design, significantly reducing failure rates in later models.
Bmw
Production years 2005–2010 meet Euro 4 emissions standards (VCA UK Type Approval #VCA/EMS/8550).
The BMW S85 B50 A is a 4,999 cc V10 naturally aspirated petrol engine engineered for high-performance sedans and coupes (2005–2010). It combines DOHC architecture with individual throttle bodies and double-VANOS to deliver linear throttle response and high-RPM performance. Designed to meet Euro 4 standards, it balances motorsport-derived engineering with everyday drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 4,999 cc | |
| Fuel type | Petrol | |
| Configuration | V10, DOHC, 40-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 92.0 mm × 75.6 mm | |
| Power output | 373 kW (507 PS) @ 8,250 rpm | |
| Torque | 520 Nm @ 6,100 rpm | |
| Fuel system | Bosch Motronic ME 9.2 electronic fuel injection | |
| Emissions standard | Euro 4 | |
| Compression ratio | 12.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Double-row roller chain (interference design) | |
| Oil type | BMW Longlife-01 (SAE 10W-60) | |
| Dry weight | 215 kg |
The naturally aspirated V10 delivers high-RPM performance ideal for spirited driving but requires adherence to 15,000 km oil change intervals to prevent timing chain and bearing wear. BMW Longlife-01 (10W-60) oil is essential due to its thermal stability and protection for the upper chain guide. Extended idling or short-trip driving accelerates wear in pre-2007 engines with original-spec tensioners. The Bosch ME 9.2 ECU is robust but sensitive to vacuum leaks; maintaining intake integrity prevents drivability issues. Post-2007 models feature revised oil galleries per BMW SIB 11 03 04, significantly enhancing long-term reliability.
Oil Specs: Requires BMW Longlife-01 specification (BMW SIB 11 03 04). ACEA A3/B3 compatible oils acceptable.
Emissions: Euro 4 certification applies to all models (2005–2010) (VCA Type Approval #VCA/EMS/8550).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities (BMW TIS Doc. A35103).
BMW Technical Information System (TIS): Docs A35103, A35143, A35203, SIB 11 03 04
VCA Type Approval Database (VCA/EMS/8550)
DIN 70020:2004 Internal Combustion Engine Power Measurement
The BMW S85 B50 A was used exclusively in BMW's E60/E63 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-reinforced engine mounts in the E60 M5 and revised intake in the E63 M6-and was replaced by the S63 twin-turbo V8 in 2011, creating strict interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side engine block near the starter motor (BMW TIS A35203). The 7th VIN digit indicates engine family ('S' for S85 series). Pre-2007 models have silver valve covers with "S85" branding; post-2007 units use black valve covers with "S85" marking. Critical differentiation from M62: S85 B50 A uses DOHC and individual throttle bodies; M62 uses SOHC and single throttle body. Service parts require production date verification - timing tensioners for engines before 08/2007 are incompatible with later units due to oil gallery redesign (BMW SIB 11 03 04).
The S85 B50 A's primary reliability risk is timing chain wear in early builds, with elevated incidence in high-mileage vehicles. Internal BMW quality reports from 2007 noted a significant share of pre-2007 engines requiring tensioner replacement before 120,000 km, while UK DVSA records show low emissions-related failures due to robust catalytic converter design. Extended oil intervals and short-trip driving increase chain stress, making oil quality and change frequency critical.
Analysis derived from BMW technical bulletins (2005-2010) and UK DVSA failure statistics (2007-2015). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW S85B50A.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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