Engines Market

BMW 850CSi SPECIALISTS

BMW 8 Series 850CSi Engine Replacement Compare Prices & Get Quotes

Need a BMW 8 Series 850CSi engine replacement- Get quotes today from trusted UK BMW 850CSi engine specialists. Compare prices on reconditioned, rebuilt and used engines for the rare S70B56 V12.

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BMW 8 Series 850CSi Engine
from£12,000 to £18,0...
  • Usedfrom £5,000
  • Reconditionedfrom £9,000
  • Common codesS70B56
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Variant History

BMW 8 Series 850CSi Engine History & Specs at a Glance

The BMW 850CSi arrived in 1992 as the flagship of the E31 8 Series range, developed by BMW's M division. Its S70B56 V12 was a heavily reworked version of the M70 engine, bored and stroked to 5.6 litres with unique internals - making it one of the most desirable classic BMW engines ever produced.

BMW 8 Series 850CSi
  1. 1990

    E31 8 Series launched with M70B50 5.0-litre V12 (296 bhp)

  2. 1992 (September) - 850CSi introduced with S70B56 5.6-litre V12

  3. 1992

    1996 - 850CSi in production; only 1,510 built worldwide, with just 138 UK right-hand drive examples

  4. 1999

    E31 production ends; no direct successor until the G15 8 Series in 2018

Every engine fitted to the BMW 8 Series 850CSi is covered below, with UK rebuilt pricing and known failure points.

Engine Codes & Pricing

BMW 8 Series 850CSi Engine Codes Specifications & Replacement Cost

Find your exact engine code, specs and UK replacement cost guide.

S70B56 — 5.6L V12 Petrol (1992-1996) engine

S70B56 — 5.6L V12 Petrol (1992-1996)

Power Output
375-380 bhp / 279 kW
Torque
406 lb-ft / 550 Nm
Years Fitted
1992-1996
Transmission
Getrag 560G 6-speed manual only
Fuel Delivery
Bosch Motronic 1.7 with two independent DME ECUs (one per cylinder bank)
Compression Ratio
9.8:1
Cylinder Configuration
V12, 60-degree bank angle, 2 valves per cylinder

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Common Problems

BMW 8 Series 850CSi Engine Problems Repair Cost vs Replacement

The S70B56 is one of BMW's most celebrated engines, but age takes its toll on every component. With the youngest 850CSi now approaching 30 years old, cooling systems, ignition components and rubber seals are the primary failure points. Rebuilt S70B56 engines through EnginesMarket include upgraded components addressing these age-related weaknesses, plus a minimum 12-month unlimited-mileage warranty.

Common failure points and repair options

Cooling System Failure

Affected
BMW 8 Series 850CSi (S70B56, 1992-1996)
Typical failure mileage
60,000-100,000 miles (age-related)
Root cause
The S70B56's cooling system uses plastic water pump impellers and ageing rubber hoses that become brittle over time. The V12's cramped engine bay (the S70 sits deep in the E31's engine compartment) makes cooling system access labour-intensive.

Repair options

Repair tierDealer priceSpecialist price
Cooling system refresh£1,500-£2,500£800-£1,500
Full Replacement - rebuilt/reconditioned engine£18,000-£25,000£12,000-£18,000
Our recommendation
For the BMW 8 Series 850CSi, preventative maintenance is always the better value. A cooling system refresh or ignition service costs a fraction of a full engine replacement and can prevent catastrophic failure. However, if the S70B56 has suffered a timing chain failure, overheating damage, or internal mechanical failure, a rebuilt engine from a specialist - with documented provenance and warranty - is the sensible path. Given the 850CSi's collector value, investing in a proper rebuild preserves both the car's usability and its investment potential.

Ignition System & Running Issues

Affected
BMW 8 Series 850CSi (S70B56, 1992-1996)
Typical failure mileage
50,000-90,000 miles
Root cause
The S70B56 uses two separate DME M1.7 engine control units - one for each cylinder bank - operating independently. Ageing coil packs, spark plugs, and the dual-DME setup can cause misfires, hesitation at high RPM, and cutting out at idle. Vacuum leaks are also common on older S70 engines.

Repair options

Repair tierDealer priceSpecialist price
Ignition system service£800-£1,500£400-£900
Full Replacement - rebuilt/reconditioned engine£18,000-£25,000£12,000-£18,000
Our recommendation
For the BMW 8 Series 850CSi, preventative maintenance is always the better value. A cooling system refresh or ignition service costs a fraction of a full engine replacement and can prevent catastrophic failure. However, if the S70B56 has suffered a timing chain failure, overheating damage, or internal mechanical failure, a rebuilt engine from a specialist - with documented provenance and warranty - is the sensible path. Given the 850CSi's collector value, investing in a proper rebuild preserves both the car's usability and its investment potential.
-> Compare rebuilt S70B56 BMW 8 Series 850CSi engine prices

Don't Let Engine Failure Write Off Your BMW 8 Series 850CSi

The S70B56 is a masterpiece of 1990s engineering, but age-related failures are inevitable. A specialist rebuild through EnginesMarket gives you upgraded components, a 12-month warranty, and nationwide delivery - all at a fraction of main dealer prices. With only 138 UK right-hand drive examples ever built, your 850CSi is worth protecting.

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FAQ

BMW 8 Series 850CSi Engine ReplacementFrequently Asked Questions

Everything BMW 8 Series 850CSi owners usually ask before choosing a rebuilt, reconditioned or used replacement engine.

Why Choose Us

Compare BMW 8 Series 850CSi Engine Prices Today

Comparing BMW 8 Series 850CSi engine replacement quotes is free, no-obligation, and specific to your exact S70B56 V12. With only 138 UK right-hand drive examples ever built, getting the right specialist for your 850CSi matters. Enter your registration and get tailored quotes from trusted UK BMW 850CSi engine specialists today.

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