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 11.6 psi. 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

N74B60

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

N74B66

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

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 430kW (577 bhp) due to emission regulations. This was partially compensated with an increase in torque to 850Nm (627 lb-ft). 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 is some markets, all N74B66TU V12 powered 7-series were long wheelbase (G12); there was no short wheelbase (G11) variant offered world wide. Applications:

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: