The BMW N74 is a twin-turbo V12 petrol engine which replaced the N73 and has been produced since 2008. It is BMW's first turbocharged V12 engine and is also used in several Rolls-Royce models.
Design The N74 features twin turbochargers, which are not present on its naturally aspirated BMW N73 predecessor. The turbochargers are located on the outside of the engine and use a boost pressure of . In its base configuration the engine has a compression ratio of 10:1 and a specific fuel consumption of 245 g·kW−1·h−1.
Like 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 EngineDisplacementPowerTorqueYearN74B60Hans-Stefan Braun, Thomas Brüner, Klaus Hirschfelder, Uwe Hoyer, Horst Kellerer, Johann Schopp, Christian Schwarz: Der neue Zwölfzylinder-Ottomotor von BMW , in MTZ - Motortechnische Zeitschrift, November 2009, Volume 70, Issue 11, pp. 848 at 5,250 rpm at 1,500–5,000 rpm 2008–2015N74B66 at 5,250 rpm at 1,500–5,000 rpm 2009–2020 at 5,600 rpm at 1,500–5,500 rpm 2013–2022 at 5,250 rpm at 1,500 rpm 2016–2020N74B66TU at 5,500 rpm at 1,500 rpm 2016–2019 at 5,500 rpm at 1,550 rpm 2020–2022N74B68 at 5,250 rpm at 1,500 rpm 2017–present
N74B60 This initial version of the N74 has a bore of and a stroke of . The redline is 7000 rpm and the compression ratio is 10.0:1.
Applications: 2009–2015 BMW F01/F02/F03 760i/760Li
N74B66
The N74B66 is an enlarged version of the N74B60, due to a stroke of . The redline is 7000 rpm and the compression ratio is 10.0:1. It produces up to and is used in the Rolls-Royce Ghost.
Year Application Power output Torque 2010–2020 Rolls-Royce Ghost 2014–2020 Rolls-Royce Ghost V-Specification 2019Eadon Green Panthean Coupe 2014–2023 Rolls-Royce Wraith 2015–2023 Rolls-Royce Dawn
N74B66TU 2016 saw the introduction of the 6.6 liter N74 V12 variant to the BMW 7-series along with some Technical Updates (TU) for reliability. The facelifted 2020 models saw power reduced in the EU market to due to the integration of Otto particle filters in the exhaust to meet emissions standards. This was partially compensated with an increase in torque to . US models enjoyed the bump in torque, with horsepower remaining close to the previous level at 600 bhp. Although the flagship 7-series was marked M760i in the USA and M760Li in some markets, all N74B66TU V12 powered 7-series were long wheelbase (G12); there was no short wheelbase (G11) variant offered worldwide.
Applications: 2016–2022 G12 M760Li xDrive
N74B68 The 6.75 litre version was introduced in the 2018 Rolls-Royce Phantom. It is also used in the Rolls-Royce Cullinan and Rolls-Royce Ghost, both of which are built on the same platform as the new Phantom.
Applications: 2017–present Rolls-Royce Phantom VIII 2018–present Rolls-Royce Cullinan 2021–present Rolls-Royce Ghost
References