BMW M70
The BMW M70 is a naturally-aspirated, SOHC, V12 petrol engine, which was BMW's first production V12[1] and was produced from 1987 to 1996.
| BMW M70 engine | |
|---|---|
 | |
| Overview | |
| Production | 1987–1994 |
| Layout | |
| Configuration | 60° V12 |
| Displacement | 5.0 L (4,988 cc) |
| Cylinder bore | 84 mm (3.31 in) |
| Piston stroke | 75 mm (2.95 in) |
| Cylinder block material | Aluminium |
| Cylinder head material | Aluminium |
| Valvetrain | SOHC |
| Combustion | |
| Fuel type | Petrol |
| Output | |
| Power output | 220 kW (295 hp) |
| Torque output | 450 N⋅m (332 lb⋅ft) |
| Chronology | |
| Predecessor | None |
| Successor | BMW M73 |
The BMW S70/2 engine, largely unrelated to the M70 and S70B56 engines, is a naturally-aspirated, DOHC, V12 petrol engine, which powered the 1993 to 1998 McLaren F1.
Design
The M70's design is similar to that of two 2.5 L M20 straight-six engines joined at a 60 degree angle,[2] due to the following features: single overhead camshaft valvetrain, bore spacing of 91 mm (3.6 in), bore of 84 mm (3.31 in), stroke of 75 mm (2.95 in), and a compression ratio of 8.8:1.[3]
The M70 has the following differences with the M20 engine:
- Aluminium alloy engine block (AluSil) instead of cast-iron (both engines have an aluminium cylinder head), to reduce weight.[4]
- Airflow measurement using Mass air flow sensors (MAFs)[5] instead of Air flow meters (AFMs) to improve fuel economy.
- Electronic Throttle Control instead of a mechanical throttle cable.
- A timing chain was used instead of a timing belt,[6] to reduce servicing requirements.
- Hydraulic valve lifters instead of mechanically adjusted tappets, to reduce servicing requirements.
The M70 has two Motronic 1.7[7] ECUs (one for each cylinder bank). To provide redundancy, the M70 also has two fuel pumps, fuel rails, distributors, mass air flow sensors, crankshaft position sensors, coolant temperature sensors and throttle bodies.[8]
Some M70 engines (such as fitted to the E32 750iL Highline) are fitted with two alternators. The second alternator is smaller and is used to charge an auxiliary battery and power equipment in the rear passenger compartment, such as a telephone, fax machine, wine cooler, independent climate control and power sun shields.[9]
Versions
| Version | Displacement | Power | Torque | Redline | Years |
|---|---|---|---|---|---|
| M70B50 | 4,988 cc (304.4 cu in) | 220 kW (295 hp)[10] at 5,200 rpm | 450 N⋅m (332 lb⋅ft) at 4,100 rpm | 6,000 | 1987–1994 |
| S70B56 | 5,576 cc (340.3 cu in) | 280 kW (375 hp) at 5,300 rpm | 550 N⋅m (406 lb⋅ft) at 4,000 rpm | 6,400 | 1992–1996 |
| S70/2 | 6,064 cc (370.0 cu in) | 461 kW (618 hp) at 7,400 rpm | 617 or 651 N⋅m (455 or 480 lb⋅ft) at 6,700 rpm | 7,500 | 1993–1998 |
| S70/3 | 5,990 cc (365.5 cu in) | 467 kW (626 hp) at 6,500 rpm[lower-alpha 1] | 670 N⋅m (494 lb⋅ft) at 4,500 rpm | 8,000 | 1998–2000 |
M70B50
Applications:
- 1987–1994 E32 750i/750iL – this was mated primarily to an automatic ZF 4HP24 transmission
- 1989–1994 E31 850i/850Ci – this was mated to either the automatic ZF 4HP24 transmission or the optional Getrag 560G
S70 engine
| BMW S70 engine | |
|---|---|
 Engine bay of a McLaren F1 | |
| Overview | |
| Production | 1992–2000 |
| Layout | |
| Configuration | 60° V12 |
| Displacement | 5.6 L (5,576 cc) 6.1 L (6,064 cc) 6.0 L (5,990 cc) |
| Cylinder bore | 86 mm (3.39 in) |
| Piston stroke | 80 mm (3.15 in) 87 mm (3.43 in) 85.9 mm (3.38 in) |
| Cylinder block material | Aluminium |
| Cylinder head material | Aluminium |
| Valvetrain | DOHC |
| Compression ratio | 11:1 |
| Combustion | |
| Fuel type | Petrol |
| Cooling system | Water-cooled |
| Output | |
| Power output | 280–671 kW (375–900 hp)*(*900 PS produced only McLaren F1 GTR Long Tail specifically in full race trim upon qualification without racing restrictors)[13][14][15][16] |
| Torque output | 550–900 N⋅m (406–664 lb⋅ft) |
| Dimensions | |
| Dry weight | 265 kg (584 lb) |
| Chronology | |
| Predecessor | None |
| Successor | None |
S70B56
The first engine to use the S70 name is a 5,576 cc (340.3 cu in) variant of the M70 engine fitted only to the E31 850CSi.[17] With 1,510 units produced, this is the lowest production BMW engine to date.[18]
Three prototype dual overhead camshaft S70 engines were constructed, prior to the decision to not produce an E31 M8 model.[19]
Applications:
- 1992–1996 E31 850CSi
- 2011 Simbol Design Lavazza GTX-R (twin-turbo version)
S70/2
The S70/2, while sharing the same 12 cylinder layout, bore spacing and design principle as the S70B56, is essentially a new design with the heads based on the European market S50B32,[20] and thus featuring 4 valves per cylinder and variable valve timing (called VANOS by BMW) and individual throttle bodies. A dry sump oiling system is used.[21] The weight of the S70/2, plus ancillaries and full exhaust, is 265 kg (584 lb).[22]
Applications:
- 1993–1998 McLaren F1
S70/3
The S70/3 is a racing engine based on the S70/2.
Applications
- 1998–1999 BMW V12 LM racing car
- 1999–2000 BMW V12 LMR racing car
- 2000 BMW X5 LM racing car[23][24][25]
References
- "BMW E32 parts". www.usautoparts.net. Archived from the original on 3 July 2013. Retrieved 4 August 2017.
- "The 8-Series Was One Of BMW's Best Failed Experiments". www.jalopnik.com. 5 June 2014. Retrieved 30 July 2017.
- "1989 BMW 750i E32 Specification". www.carfolio.com. Retrieved 4 August 2017.
- "BMW M70, M72 and M73 V12 Engines". www.unixnerd.demon.co.uk. Archived from the original on 7 January 2016. Retrieved 4 August 2017.
- "7' E32 750iL Mass air flow sensor". www.realoem.com. Retrieved 30 July 2017.
- "7' E32 750iL Timing and valve train-timing chain". www.realoem.com. Retrieved 30 July 2017.
- "BMW" (PDF). Archived from the original (PDF) on 2 February 2019. Retrieved 1 February 2019.
- "V12 (M70) Regular Maintenance". www.bmwe32.masscom.net. Retrieved 4 August 2017.
- "Engines Exposed: Just How Far Has BMW's Beastly V12 Come?". www.carbuzz.com. 5 February 2016. Retrieved 30 July 2017.
- "BMW M70B50 V12-Zylinder-Ottomotor". bmw-grouparchiv.de. Retrieved 6 February 2021.
- "Le Mans '99". bmw-grouparchiv.de. Retrieved 9 June 2019.
- "Diamètre des brides / Air rectrictors diameter" (PDF). lemans-history.com. Retrieved 9 June 2019.
- "McLaren F1 GTR Longtail stretches its legs at Spa-Francorchamps".
- "1997 McLaren F1 GTR Long Tail | McLaren". 18 April 2016.
- "Street-Legal McLaren F1 GTR Longtail Has Rich History, $15 Million Asking Price". Carscoops. 2020-06-18. Retrieved 2022-08-12.
- "Engine specifications for Motorsport engines". www.bmwheaven.com. Retrieved 4 August 2017.
- "Worldwide Shipments: S70 850CSi 1992–1996". www.8coupe.com. Retrieved 4 August 2017.
- "BMW S70 and S70/2 V12 Engines". www.unixnerd.demon.co.uk. Archived from the original on 19 August 2017. Retrieved 4 August 2017.
- "BMW Classic – Recherche-Client". bmw-grouparchiv.de. Retrieved 28 February 2018.
- "1994 McLaren F1: First Drive Flashback". Road & Track. 14 December 2014. Retrieved 4 May 2017.
- "F1 – McLaren's Road Car An Autocar & Motor Book". www.audiosignal.co.uk. Retrieved 4 August 2017.
- "BMW Shows the X5 le Mans Concept and Its V12 Engine with 700+ HP".
- "2001 BMW X5 le Mans Concept Had the V-12 Heart of a McLaren F1". 16 June 2020.
- "The BMW X5 le Mans".
