BMW N55

BMW N55 engine
Overview
Manufacturer	BMW
Production	2009–present
Combustion chamber
Configuration	Straight-6
Chronology
Predecessor	BMW N54
Successor	BMW B58

The BMW N55 is a turbocharged direct injection straight-6 DOHC engine which began production in 2009 and presently (2015) remains in production. It was launched in the F07 535i Gran Turismo.^[1] The N55 began to be phased out following the introduction of the B58 engine in 2015.^[2]

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.

Models

N55B30M0 (225 kW)

Applications:

• 2010-2013 E90/E91/E92/E92N/E93 335i
• 2009-present (2015) F07 535i GT
• 2010-2013 E82 135i
• 2010-2013 E70 X5 xDrive 35i
• 2010-present (2015) F25 X3 xDrive35i
• 2013-present (2015) E84 X1 xDrive35i
• 2010-present (2015) F10 535i
• 2012–2015 BMW F30 335i
• 2011–2014 E71 X6 xDrive 35i
• 2014-present (2015) F16 X6 xDrive35i
• 2014-present (2015) F26 X4 xDrive 35i
• 2014-present (2016) F15 x5 xDrive 35i

N55B30O0 (235 kW)

Applications:

• 2011-present (2015) F12 640i^[3]
• 2012-2015 F20 M135i^[4][5]
• 2012-2015 F01 740i/Li
• 2012-2013 E82/E88 135is^[6]

N55B30O0 (240 kW)

Applications:

• 2015-2016 F20 M135i LCI
• 2013-2016 F22/F23 M235i

N55HP (250 kW)

Applications:

• 2013-2015 F30 ActiveHybrid 3

N55B30T0 (265 kW)

Applications:

• 2015-present (2015) F26 X4 M40i

N55B30T0 (272 kW)

Applications:

• 2016-present (2016) F87 M2

Alpina N55R20A^[7] (301 kW)

Biturbo engine by Alpina based on the N55B30M0. Applications:

• 2013-present (2016) Alpina F30/F31 B3 Bi-Turbo
• 2013-present (2016) Alpina F32 B4 Bi-Turbo
• 2014-present (2016) Alpina F33 B4 Bi-Turbo

Design

While its N54 predecessor uses parallel twin-turbochargers, the N55 uses a single twin scroll turbocharger.^[8][9] 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).^[10]

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.^[11]

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.^[10]

The engine includes BOSCH MEVD 17.2 engine management, and supports ROZ(RON) 91-98 octane fuel types (recommended RON 95),^[12][13] 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.^[14]

The N55 is mated to ZF's 8-speed automatic transmission in later applications such as the 2011 535i and 2013 BMW 740i,^[15] 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.^[16][17]

While having the same displacement and peak power output as the N54, the N55 is 15% more fuel efficient, has lower emissions,^[18] less turbo lag and better low-rev torque.^[10][19] Despite aftermarket support being more ubiquitous for the N54 (as of 2016), the N55 aftermarket scene is quickly closing in on its predecessor in terms of options available, as well as showing respectable reliability when pushed for increased horsepower north of 550 horsepower to the wheels when coupled with supplemental fuel upgrades.

S55

BMW 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.^[20][21]

S55B30T0 (317 kW)

• 2013-current F80 M3
• 2013-current F82/F83 M4

See also

• List of BMW engines

References

External links

• http://www.bmwblog.com/2010/09/12/dyno-test-bmw-335i-and-335is-n54-vs-n55-engine/ comparison of N54 and N55 dyno results