BMW N55 S55 Straight-6 Engine

The BMW  N55 is a turbocharged in- line six-cylinder DOHC engine in four-valve technology from BMW . It was introduced at the end of 2009 in the BMW 5 Series Gran Turismo (535i GT) and is BMW's first twin-scroll turbocharged engine with a Valvetronics system and direct injection . BMW calls this system BMW TwinPower Turbo . 
Successor was from 2015 the BMW B58 modular engine 

The engine with two overhead camshafts has, like its predecessor, an aluminum crankcase (engine block) in open deckand bedplate construction. The crankshaft is made of cast iron and is 3 kg lighter than that of the N54, which was forged. The cylinder head is made of aluminum. The intake valves have a diameter of 32.0 mm, the exhaust valves are sodium-filled.

An innovation over the predecessor engine N54 B30, in which two turbochargers were used, is that the N55 has only one turbocharger: the so-called twin-scroll loader , which has two separate spirals, which lead the exhaust gas to the turbine wheel , While three cylinders were each responsible for a turbocharger on the N54, three cylinders are each responsible for one of the two spirals for driving the turbocharger on the N55. This turbocharger design saves compared to the previous N54 4 kg weight, see link bimmertoday 2009.

Another new addition to the twin-scroll turbocharger is that the turbocharger with direct injection and Valvetronic wascombined for the first time with the N55 . Valvetronic is the infinitely variable regulation of the lift of the intake valves, which makes the throttle valve superfluous. Nevertheless, this is redundant. The Valvetronic thus controls the air mass supplied for combustion in the engine itself. Combining these three systems has further reduced fuel consumption and improved response to the N54.

For BMW M models, the engine is available as a sport version BMW S55 with up to 368 kW (500 hp). The most powerful variant in the M4 GTS uses water injection . 

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.

Engine Models

N55B30M0 (225 kW) 306 hp

Applications:

• since 11/2009 in F07 as 535i Gran Turismo
• since 03/2010 in F10 as 535i
• since 03/2010 in the E90 / E91 / E92 / E93 as 335i
• since 03/2010 in E82 / E88 as 135i
• since 03/2010 in the E71 as X6 xDrive35i
• since 06/2010 in the E70 as X5 xDrive35i
• since 09/2010 in F11 as 535i Touring
• since 11/2010 in the F25 as X3 xDrive35i
• since 10/2011 in F30 / F31 as 335i
• since 06/2013 in the F34 as 335i Gran Turismo
• since 07/2013 in F32 / F33 / F36 as 435i
• since 12/2013 in the F15 as X5 xDrive 35i
• since 07/2014 in F26 as X4 xDrive 35i

N55B30 (235 kW) 320 hp

Applications:

• since 03/2011 in the BMW 6 Series as 640i
• since 07/2012 in the BMW 7 Series as 740i
• since 09/2012 in BMW 1 Series as M135i
• from 2012 in the Roding Roadster

N55B30O0 (240 kW) 326 hp

2015-2016 F20 M135i  enngine specification

Applications:

• since 03/2010 in the E90 / E91 / E92 / E93 as 335i with BMW M Performance Power Kit
• since 03/2010 in the E82 / E88 as 135i with BMW M Performance Power Kit
• since 10/2011 in the F30 / F31 as 335i and 335i xDrive with BMW M Performance Power Kit until 07/2013
• since 07/2013 in the F34 as 335i and 335i xDrive Gran Turismo with BMW M Performance Power Kit until 07/2013
• since 07/2013 in F10 / F11 as 535i and 535i xDrive with BMW M Performance Power Kit from 07/2013
• since 03/2014 in the BMW 2 Series as M235i
• since 03/2015 in BMW 1 Series as M135i

N55HP (250 kW) 340 hp

Applications:

• since 07/2013 in F30 / F31 as 335i and 335i xDrive with BMW M Performance Power Kit from 07/2013
• since 07/2013 in F34 as 335i and 335i xDrive Gran Turismo xDrive with BMW M Performance Power Kit from 07/2013
• since 07/2013 in F32 / F33 / F36 as 435i and 435i xDrive with BMW M Performance Power Kit

N55B30T0 (265 kW) 360 hp

Applications:

• 2015–present F26 X4 M40i

N55B30T0 (272 kW) 370 hp

Applications:

• 2016–present (2016) F87 M2

Alpina N55 (301 & 324 kW)

Biturbo engine by Alpina based on the N55B30M0. The crankcase is of a different design and specially cast by BMW for Alpina.

N55R20A (301 kW)

Applications:

• 2013–2017 Alpina F30/F31 B3 Bi-Turbo
• 2013–2017 Alpina F32 B4 Bi-Turbo
• 2014–2017 Alpina F33 B4 Bi-Turbo

Second version (324 kW)

Applications:

• 2017–present Alpina F30/F31 B3 S Bi-Turbo
• 2017–present Alpina F32/F33 S B4 Bi-Turbo

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.

BMW F82/F83 M4 Engine specification

S55B30T0 (317 kW)

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

S55B30T0 Design R6 Displacement 2979cm3 Power at speed 317kw=425hp 5500-7500 rpm Power output per liter (kw/l) 106.4 Torque at speed 550Nm at 1850-5500 rpm CR 10.2:1 fuel consumption (L/100KM) 8.3-8.8 CO2 emissions grams per km 194-204 Digital engine electronics MEVD17.2.G ULEV2