Production 2009–present | ||
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The BMW N55 is a turbocharged direct injection straight-6 DOHC engine which began production in 2009. It was launched in the F07 535i Gran Turismo. The N55 began to be phased out following the introduction of the B58 engine in 2015.
Contents
- N55B30M0 225 kW
- N55B30 235 kW
- N55B30O0 240 kW
- N55HP 250 kW
- N55B30T0 265 kW
- N55B30T0 272 kW
- Alpina N55R20A 301 kW
- Design
- S55
- S55B30T0 317 kW
- References
Compared with its N54 predecessor, the N55 features a single twin-scroll turbo (the N54 uses twin turbos) and variable valve lift (called Valvetronic by BMW).
The F80 M3 and F82 M4 are powered by the S55 engine, which is the high performance version of the N55.
N55B30M0 (225 kW)
Applications:
N55B30 (235 kW)
Applications:
N55B30O0 (240 kW)
Applications:
N55HP (250 kW)
Applications:
N55B30T0 (265 kW)
Applications:
N55B30T0 (272 kW)
Applications:
Alpina N55R20A (301 kW)
Biturbo engine by Alpina based on the N55B30M0. The crankcase is of a different design and specially cast by BMW for Alpina.
Applications:
Design
While its N54 predecessor uses parallel twin-turbochargers, the N55 uses a single twin scroll turbocharger. BMW has used the term "TwinPower Turbo" to describe both twin-turbo and (single turbocharger) twin-scroll systems. Another difference is that the N55 has variable valve lift (called Valvetronic by BMW). Displacement and peak power output are the same as the N54, however fuel economy is improved 15%, emissions have been reduced, less turbo lag and better low-rev torque.
As per the N54, the bore is 84 mm (3.3 in), the stroke is 89.6 mm (3.5 in) and the capacity is 2,979 cc (181.8 cu in). The compression ratio is 10.2:1. The N54's gasoline direct injection system uses piezo injectors, also used in the naturally-aspirated N53 (mostly European markets only), the N55's direct injection uses Bosch solenoid-type injectors. The piezo injectors were more expensive and BMW decided they were not worthwhile in North America, in contrast to Europe which they could perform lean burn to reach their full potential.
The exhaust manifold design, called Cylinder-bank Comprehensive Manifold (CCM) by BMW, aims to reduce the pressure fluctuations to reduce throttle lag and exhaust back-pressure.
The engine includes BOSCH MEVD 17.2 engine management, and supports ROZ(RON) 91-98 octane fuel types (recommended RON 95), Valvetronic III (variable valve lift control) with double VANOS, direct injection and turbocharging. Turbocharging uses 2 sets of exhaust duct to turn 1 turbine wheel, with cylinders 1-3 and 4-6 combined to form 2 exhaust channels.
The N55 is mated to ZF's 8-speed automatic transmission in later applications such as the 2011 535i and 2013 BMW 740i, retaining the previous ZF 6-speed automatic transmission in earlier models. A 6-speed manual is usually available for sedans (excluding the 7-Series, and dropped for the 5 and 6 series for 2015), but not crossovers such as the X3, X5 and X6, and is of limited availability within the United States. The N55 engines in the 2011 BMW 135i and 2013 BMW 135is are mated to a Getrag 7-speed Dual-clutch transmission or a 6-speed manual transmission.
S55
The S55 engine is the high performance version of the N55 engine. Differences compared with the N55 include a closed-deck engine block, lightweight crankshaft, strengthened pistons, different valve material, twin turbos, twin fuel pumps, active exhaust and revised intercoolers.