BMW N74

BMW N74 engine
Overview
Production	2008–present
Layout
Configuration	60° V12
Displacement	6.0–6.7 L (366–409 cu in)
Cylinder block material	Aluminium
Cylinder head material	Aluminium
Valvetrain	DOHC with VVT
Combustion
Turbocharger	Twin-turbo
Fuel type	Petrol
Chronology
Predecessor	BMW N73

Cutaway view of N74

The BMW N74 is a twin-turbo V12 petrol engine which replaced the N73 and has been produced from 2008 to present, production will end in 2023. It is BMW's first turbocharged V12 engine and is also used in several Rolls-Royce models.

Design

Compared with its naturally aspirated BMW N73 predecessor, the N74 features twin-turbochargers. The turbochargers are located on the outside of the engine and use a boost pressure of 11.6 psi (0.8 bar). In its base configuration, the engine has a compression of $\varepsilon =10$ and a specific fuel consumption of 245 g·kW⁻¹·h⁻¹

As per its predecessor, the N74 has direct injection, DOHC and variable valve timing (called double-VANOS by BMW). However, the N74 does not have variable valve lift (called Valvetronic by BMW).

The N74 marked BMW's first use of an 8-speed automatic transmission, in the form of the ZF 8HP90.

Versions

Engine	Displacement	Power	Torque	Year
N74B60	5,972 cc (364.4 cu in)	400 kW (536 hp) at 5,250 rpm	750 N⋅m (553 lb⋅ft) at 1,500–5,000 rpm	2009–present
N74B66	6,592 cc (402.3 cu in)	420 kW (563 hp) at 5,250 rpm	780 N⋅m (575 lb⋅ft) at 1,500–5,000 rpm	2009–present
		465 kW (624 hp) at 5,600 rpm	800 N⋅m (590 lb⋅ft) at 1,500–5,500 rpm	2013–present
		442 kW (593 hp) at 5,250 rpm	840 N⋅m (620 lb⋅ft) at 1,500 rpm	2016–present
N74B66TU		449 kW (602 hp) at 5,500 rpm	800 N⋅m (590 lb⋅ft) at 1,500 rpm	2016–present
N74B68	6,749 cc (411.8 cu in)	420 kW (563 hp) at 5,250 rpm	900 N⋅m (664 lb⋅ft) at 1,500 rpm	2017-present

N74B60

This initial version of the N74 has a bore of 89 mm (3.5 in) and a stroke of 80 mm (3.1 in). The redline is 7000 rpm and the compression ratio is 10.0:1.

Applications:

• 2008–2015 F01/F02/F03 760i/760Li

N74B66

N74 in Rolls Royce Ghost

The N74B66 is an enlarged version of the N74B60, due to a stroke of 88 mm (3.5 in). The redline is 7000 rpm and the compression ratio is 10.0:1. It produces up to 465 kW (624 hp) and is used in the Rolls-Royce Ghost.

Applications:

• 2010–present Rolls-Royce Ghost 420 kW (563 hp) / 780 N⋅m (575 lb⋅ft)
• 2014–present Rolls-Royce Ghost V-Specification 442 kW (593 hp) / 575 lb⋅ft (780 N⋅m)
• 2014–present Rolls-Royce Wraith, 465 kW (624 hp) / 800 N⋅m (590 lb⋅ft)
• 2015–present Rolls-Royce Dawn 420 kW (563 hp) / 820 N⋅m (605 lb⋅ft)

N74B66TU

Applications:

• 2016-present G12 M760Li xDrive

N74B68

The 6.8 litre version was introduced in the 2018 Rolls-Royce Phantom. It is also used in the Rolls-Royce Cullinan SUV, built on the same platform as new Phantom.

Applications:

• 2017-present Rolls-Royce Phantom VIII
• 2018-present Rolls-Royce Cullinan