via BIMMERPOST.com Technical training. Product information. N55 Engine. BMW Service via BIMMERPOST.com General information Symbols used The following symbol/graphic representation is used in this document to facilitate better comprehen¬ sion or to draw attention to very important information: A contains important safety notes and information that needs to be observed strictly in order to guaran¬ tee the smooth operation of the system. Information status and national variants BMW Group vehicles meet the requirements of the highest safety and quality standards. Changes in requirements for environmental protection, customer benefits and design render necessary continu¬ ous development of systems and components. Consequently, there may be discrepancies between the contents of this document and the vehicles available in the training course. This document basically relates to left-hand drive vehicles with European specifications. Some con¬ trols or components are arranged differently in right-hand drive vehicles than shown in the graphics in this document. Further differences may arise as the result of the equipment variants used in specific markets or countries. Additional sources of information Further information on the individual topics can be found in the following: • Owner's Handbook • Integrated Service Technical Application. Contact: conceptinfo@bmw.de ©2009 BMW AG, Munchen Reprints of this publication or its parts require the written approval of BMW AG, Munchen The information contained in this document form an integral part of the technical training of the BMW Group and are intended for the trainer and participants of the seminar. Refer to the latest relevant infor¬ mation systems of the BMW Group for any changes/additions to the Technical Data. Information status: July 2009 VH-23/lnternational Technical Training via BIMMERPOST.com N55 Engine. Contents 1. Introduction.1 1.1. Highlights.1 1.1.1. Technical data.1 1.1.2. Full load diagram.1 1.2. New features/changes.3 1.2.1. Overview.3 2. Models..6 2.1. N54B3000 engine variants.6 2.2. History.7 3. Engine identification.8 3.1. Engine designation and engine identification.8 3.1.1. Engine designation.8 3.1.2. Engine designation.9 4. Engine mechanical system.11 4.1. Engine housing.11 4.1.1. Engine block.11 4.1.2. Cylinder head.15 4.1.3. Cylinder head cover.16 4.1.4. Oil pan.21 4.2. Crankshaft drive system.22 4.2.1. Crankshaft and bearings.22 4.2.2. Connecting rod and bearing.23 4.2.3. Pistons with piston rings.26 4.3. Camshaft drive.28 5. Valve gear..29 5.1. Design.29 5.1.1. Camshafts.30 5.1.2. Valve timing.31 5.1.3. Intake and exhaust valves.32 5.1.4. Valve springs.32 5.2. Valvetronic.32 5.2.1. VANOS.32 5.2.2. Valve list adjustment.35 6. Belt drive and ancillary components.42 6.1. Belt drive.42 6.1.1. Vibration absorber.43 via BIMMERPOST.com N55 Engine. Contents 7. Oil supply.46 7.1. Oil circuit.46 7.1.1. Oil ducts.46 7.1.2. Oil return.50 7.1.3. Oil pump and pressure control.52 7.1.4. Oil filtration and oil cooling.54 7.1.5. Oil spray nozzles.54 7.1.6. Oil monitoring.54 8. Air intake and exhaust system.55 8.1. Air intake system.55 8.1.1. Overview.55 8.1.2. Air intake system.58 8.1.3. Fuel tank ventilation system.59 8.2. Exhaust system.60 8.2.1. Overview.60 8.2.2. Exhaust manifold.61 8.2.3. Exhaust turbocharger.63 8.2.4. Catalytic converter.66 9. Vacuum system.68 9.1. Design.68 9.1.1. Vacuum pump.68 10. Fuel preparation..71 10.1. Overview.71 10.1.1. Fuel pressure sensor.72 10.1.2. High pressure pump.73 10.1.3. Fuel injectors.74 11. Cooling system.75 11.1. Overview.75 11.1.1. Coolant ducts.79 12. Engine electrical system.82 12.1. Connection to vehicle electrical system.82 12.1.1. Overview.82 12.1.2. System circuit diagrams.83 12.1.3. Engine control unit.89 12.2. Functions.90 12.2.1. Fuel supply system.90 N55 Engine. Contents 12.2.2. Boost pressure control.91 12.2.3. Engine cooling.91 12.2.4. System protection.92 12.3. Sensors.92 12.3.1. Crankshaft sensor.92 12.3.2. Ignition coil and spark plug.94 12.3.3. Oil pressure sensor.94 12.3.4. Oxygen sensors.95 12.3.5. Hot-film air mass meter.96 12.4. Actuators.97 12.4.1. Valvetronic servomotor.97 12.4.2. High pressure fuel injection valve.99 13. Service information.102 13.1. Engine mechanical system.102 13.1.1. Engine casing components.102 13.2. Fuel conditioning system.102 13.2.1. Overview.102 13.3. Engine electrical system.103 13.3.1. Ignition coil and spark plug.103 N55 Engine. 1. Introduction 1.1. Highlights The N55 engine is the successor to the N54 engine. Re-engineering and modifications have made it possible to now use only one exhaust turbocharger. Against the backdrop of reduced costs and im¬ proved quality, the technical data have remained virtually the same. 1.1.1. Technical data Unit N54B3000 (E71 / X6 xDrive35i) N55B30M0 (F07/535i) Configuration 6 inline 6 inline Cylinder capacity [cm 3 ] 2979 2979 Bore/stroke [mm] 84.0/89.6 84.0/89.6 Power output at engine speed [kW/bhp] [rpm] 225/306 5800 - 6250 225/306 5800 - 6400 Power output per litre [kW/l] 75.53 75.53 Torque at engine speed [Nm] [rpm] 400 1300-5000 400 1200-5000 Compression ratio [e] 10.2 10.2 Valves/cylinder 4 4 Fuel consumption, EU combined [1/100 km] 10.9 8.9 CO 2 emission g/km 262 209 Digital Motor Electron¬ ics MSD81 MEVD17.2 Exhaust emission leg¬ islation EURO, US EURO 4 EURO 5 Engine oil specifica¬ tion BMW Longlife-01 BMW Longlife-01 FE BMW Longlife-04 Top speed [km/h] 240 250 Acceleration 0 - 100 km/h [s] 6.7 6.3 Vehicle kerb weight DIN/EU [kg] 2070/2145 1940/2015 * = Electronically governed 1.1.2. Full load diagram Compared to the predecessor, the N55 engine is characterised by lower fuel consumption with the same power output and torque data. via BIMMERPOST.com 1 N55 Engine. 1. Introduction Nm 500 1500 2500 3500 4500 5500 6500 7500 1/min N55B30M0 N54B3000 Full load diagram E90 335i with N54B3000 engine compared to the F07 535i with N55B30M0 engine kW 240 220 200 180 160 140 120 100 80 60 40 20 0 cn cn w 8 o 2 via BIMMERPOST.com N55 Engine. 1. Introduction 1.2. New features/changes 1.2.1. Overview Assembly Compo¬ nent New de- vel- op- ment Same de¬ sign Remarks Engine mechanical system • Engine cas- Crankcase • Adapted for monoturbo. Cylinder bore changes to 84 mm. Large longitudinal ventilation holes. Modified oil supply to vacuum pump. ing compo¬ nents Cylinder head • Integrated water channel for injector cooling. • Crankshaft drive Cylinder head cover • Integration of blow-by pipe. Crankcase ventilation. • Camshaft drive Crankshaft Pistons and connecting rods • • Asymmetric counterweight arrangement and reduced weight. Formed hole in small connecting rod eye. Lead-free big-end bearing shells. Valve gear • Design • Valvetronic VANOS Valvetronic • • Solenoid valves with integrated non-re¬ turn valve and 3 screen filters. Increased adjustment speed and reduced susceptibility to soiling. Updated and integrated in cylinder head. 3rd generation brushless servomotor. Position detection of eccentric shaft inte¬ grated in servomotor. Belt drive and aux¬ iliary equipment Belt drive • Newly developed belt drive and vibration absorber. Oil system • Oil circuit Oil supply • Intake pipe, oil deflector and oil collector integrated in one component. Oil pump with Duroplast slide valve and characteristic map control. Modified oil filter housing. Air intake and ex¬ haust system Exhaust turbocharg¬ er • Twin scroll exhaust turbocharger with wastegate valve and electric diverter valve. • Air intake system • Exhaust sys¬ tem Catalytic converter • No underbody catalytic converter. via BIMMERPOST.com 3 N55 Engine. 1. Introduction Assembly Compo- New Same Remarks nent de- de- vel- sign op- ment Vacuum system Vacuum • Modified, similar to N63 engine, pump • Design Fuel conditioning Fuel injec- • Solenoid valve fuel injectors. system tors • Overview Cooling system Coolant ducts • Adapted for one exhaust turbocharger. • Overview Engine electrical Crankshaft • Integrated for MSA. system sensor • Connection Digital Mo¬ tor Elec- • Mounted on the intake manifold and cooled by intake air. to vehicle electrical system tronics (DME) Hot-film air • Improved signal quality and temperature • Functions mass meter (HFM) resistance. • Sensors Oxygen • Adopted from N63 engine (LSU ADV). sensor • Actuators Oil pres- • New sensor for absolute pressure mea- sure sensor surement. Oil temper¬ ature sen- • Mounted in main oil duct. sor Ignition • With higher ignition voltage and improved coils EMC Spark plugs • Spark plug, common part with N63 en¬ gine. Fuel injec¬ tors • Solenoid valve fuel injectors. 4 via BIMMERPOST.com N55 Engine. 1. Introduction N55 Engine via BIMMERPOST.com 5 T008-2150 N55 Engine. 2. Models. 2.1. N54B3000 engine variants Model Version Series Displace¬ ment in cm 3 Stroke/ bore in mm Power output in kW/bhp at rpm Torque in Nm at rpm 135i ECE E82, E88 2979 89.6/84.0 225/306 5800- 6250 400 1300- 5000 135i US E82, E88 2979 89.6/84.0 300 SAE hp 5800- 6250 407 (300 ft lbs) 1400- 5000 335i ECE E90, E91, E92, E93 2979 89.6/84.0 225/306 5800- 6250 400 1300- 5000 335i xDrive ECE E90, E91, E92 2979 89.6/84.0 225/306 5800- 6250 400 1300- 5000 335i US E90, E92, E93 2979 89.6/84.0 300 SAE hp 5800- 6250 407 (300 ft lbs) 1400- 5000 335i xDrive US E90, E92 2979 89.6/84.0 300 SAE hp 5800- 6250 407 (300 ft lbs) 1400- 5000 Z4 sDrive35i ECE E89 2979 89.6/84.0 225/306 5800- 6250 400 1300- 5000 Z4 sDrive35i US E89 2979 89.6/84.0 300 SAE hp 5800- 6250 407 (300 ft lbs) 1400- 5000 535i US E60 2979 89.6/84.0 300 SAE hp 5800- 6250 407 (300 ft lbs) 1400- 5000 535i xDrive US E60, E61 2979 89.6/84.0 300 SAE hp 5800- 6250 407 (300 ft lbs) 1400- 5000 X6 xDrive35i ECE E71 2979 89.6/84.0 225/306 5800- 6250 400 1300- 5000 6 via BIMMERPOST.com N55 Engine 2. Models. Model Version Series Displace¬ ment in cm 3 Stroke/ bore in mm Power output in kW/bhp at rpm Torque in Nm at rpm X6 xDrive35i US E71 2979 89.6/84.0 300 SAE hp 5800- 6250 407 (300 ft lbs) 1400- 5000 740i ECE F01, F02 2979 89.6/84.0 240/326 5800- 6250 450 1500- 4500 ECE = Europe version, adapted to the respective markets with option code. US = US version, adapted to the respective markets with option code. 2.2. History 6-cylinder petrol engine with exhaust turbocharger at BMW Unit 745i 745i Engine M30B32 M30B32 Series E23 E23 Cylinder capacity [cm 3 ] 3210 3430 Power output [kW/bhp] 185/252 185/252 Torque [Nm/(rpm)] 380/4000 388/2200 Engine manage¬ ment DME DME Compression ratio [e] 7.0: 1 00 b V max [km/h] 222 227 Acceleration 0-100 km/h [s] 7.8 7.9 First used 1980 1983 Last used 1983 1986 via BIMMERPOST.com 7 N55 Engine. 3. Engine identification. 3.1. Engine designation and engine identification 3.1.1. Engine designation This PI describes the following version of the N55 engine: N55B30M0. In the technical documentation, the engine designation is used for unique identification of the engine. In the technical documentation you will also find the abbreviated engine designation, i.e. N55, that only indicates the engine type. Item Description Index/explanation 1 Engine developer M, N = BMW Group P = BMW Motorsport S = BMW M GmbH W = Other-make engines 2 Engine type 1 = Straight 4 (e.g. N12) 4 = Straight 4 (e.g. N43) 5 = Straight 6 (e.g. N53) 6 = V8 (e.g. N63) 7 = VI2 (e.g. N73) 8 = VI0 (e.g. S85) 3 Change to basic engine con¬ cept 0 = Basic engine 1 to 9 = Changes, e.g. com¬ bustion process 4 Operating principle or fuel supply and installation position if applicable B = Petrol, longitudinal instal¬ lation D = Diesel, longitudinal instal¬ lation H = Hydrogen 5 Displacement in litres 1 = 1 litre + 6 Displacement in 1/10 litre 8 = 0.8 litres = 1.8 litres 7 Performance class K = Smallest U = Lower M = Medium 0 = Upper (standard) T = TOP S = Super 8 Re-engineering subject to ap¬ proval 0 = New development 1 - 9 = Re-engineering 8 via BIMMERPOST.com N55 Engine. 3. Engine identification. Breakdown of N55 engine designation Index Description N BMW Group Development 5 Straight 6 engine 5 Engine with direct injection, Valvetronic and ex¬ haust turbocharger B Petrol engine, longitudinal 30 3.0-litre capacity M Medium performance class 0 New development 3.1.2. Engine designation The engines are marked on the crankcase with an engine identification code for unique identification. This engine identifier is also required for approval by the authorities. The N55 engine further develops this identification system and the code has been reduced from previ¬ ously eight to seven characters. The engine serial number can be found under the engine identifier on the engine. Together with the engine identifier, this consecutive number enables unique identification of each individual engine. Item Description Index/explanation 1 Engine developer M, N = BMW Group P = BMW Motorsport S = BMW M GmbH W = Other-make engines 2 Engine type 1 = Straight 4 (e.g. N12) 4 = Straight 4 (e.g. N43) 5 = Straight 6 (e.g. N53) 6 = V8 (e.g. N63) 7 = VI2 (e.g. N73) 8 = VI0 (e.g. S85) 3 Change to basic engine con¬ cept 0 = Basic engine 1 to 9 = Changes, e.g. com¬ bustion process 4 Operating principle or fuel supply and installation position if applicable B = Petrol, longitudinal instal¬ lation D = Diesel, longitudinal instal- lation H = Hydrogen via BIMMERPOST.com 9 N55 Engine. 3. Engine identification Item Description Index/explanation 5 Displacement in litres 1 = 1 litre + 6 Displacement in 1/10 litre 8 = 0.8 litres = 1.8 litres 7 Type approval requirements A = Standard (modifications that require re- B - Z = as required, e. g. newed type approval testing) RON 87 N55 engine, engine identification and engine serial number Index Description Engine developer, BMW Group Change to basic engine concept, turbocharging, Valvetronic, direct fuel injection Displacement in 1/10 litre, 3 litre Operating principle or fuel supply and installation position, petrol engine longitudinal 08027053 Individual consecutive engine serial number Engine type, straight 6 Type approval requirements, standard 10 via BIMMERPOST.com N55 Engine. 4. Engine mechanical system. 4.1. Engine housing The engine housing consists of the engine block (crankcase and bedplate), cylinder head, cylinder head cover, oil pan and gaskets. 4.1.1. Engine block The engine block is made from an aluminium diecasting and consists of the crankcase with bedplate. Crankcase and bedplate The crankcase features cast cylinder liners (2) made from cast iron. A new feature is that the webs be¬ tween two cylinders now have a groove (3). Coolant can flow along these grooves from one side of the crankcase to the other, thus cooling the webs. As opposed to the N54 engine, five oil return ducts on the exhaust side (4) now permit oil to return from the cylinder head into the oil pan. These oil return channels extend into the bedplate up to below the oil deflector. They help reduce churning losses as the returning engine oil can no longer reach the crank drive even at high transverse acceleration. Five oil return channels on the intake side (5) also ensure that the blow-by gasses can flow unobstruct¬ ed from the crankshaft area into the cylinder head and to the crankcase breather in the cylinder head cover. The cooling duct (1) in the engine block is split and coolant flows directly through it. 11 N55 Engine. 4. Engine mechanical system. N55 engine, crankcase with web cooling Index Description 1 Cooling duct 2 Cylinder liner 3 Groove 4 Oil return ducts, exhaust side 5 Oil return ducts, intake side 12 N55 Engine. 4. Engine mechanical system. © © © © © N55 engine, bedplate from below Index Description 1 Oil pump 2 Oil return ducts, intake side 3 Bedplate 4 Oil deflector 5 Intake manifold with oil screen filter 6 Oil return ducts, exhaust side Ducts are provided for the oil supply to the vacuum pump as it is now lubricated by filtered oil and not by unfiltered oil as on the N54 engine. The oil pressure control valve has been integrated for the map- controlled oil pump. 13 N55 Engine. 4. Engine mechanical system. N55 engine, oil pressure control Index Description 1 Oil pressure control valve 2 Oil pump The crankcase has larger bored longitudinal ventilation holes. The longitudinal ventilation holes im¬ prove the pressure equalisation of the oscillating air columns that are created by the up and down movement of the pistons. 14 N55 Engine. 4. Engine mechanical system. N55 engine, ventilation holes in crankcase In addition, the connections at the mono turbocharger have been adapted for the oil supply and coolant cooling. 4.1.2. Cylinder head The cylinder head of the N55 engine is a new development. Direct fuel injection with exhaust tur¬ bocharging and Valvetronic are used for the first time on a BMW 6-cylinder engine. The cylinder head features a very compact design and is equipped with third generation Valvetronic. A The combination of exhaust turbocharger, Valvetronic and direct fuel injections is referred to as Tur- bo-Valvetronic-Direct-Injection (TVDI). 15 N55 Engine. 4. Engine mechanical system. This system reduces CO 2 emission and fuel consumption by 3 - 6 %. There are now no connections for the VANOS non-return valves as they have been integrated in the solenoid valves. The cylinder head further features cooling channels about the fuel injectors, providing indirect cooling. N55 engine, cylinder head 4.1.3. Cylinder head cover Design The cylinder head cover is a new development. The vacuum accumulator for the vacuum system is in¬ tegrated in the cylinder head cover. All components for crankcase ventilation and the blow-by channels are also integrated in the cylinder head cover. The integrated non-return valves ensure that the blow-by gasses are reliably added to the intake air. The N55 engine is equipped with a vacuum-controlled crankcase ventilation system. A regulated neg¬ ative pressure of approx. 38 mbar is maintained. 16 N55 Engine. 4. Engine mechanical system. N55 engine, cylinder head cover with crankcase ventilation Index Description 1 Connection, blow-by gas to clean air pipe 2 Connection, vacuum line to vacuum pump 3 Reserve, vacuum connection 4 Vacuum connection to electropneumatic pressure converter EPDW for wastegate valve 5 Duct for blow-by gas feed into intake system with integrated non-return valve 6 Blow-by gas duct with settling chamber, impact plate, pressure control valve and non-return valves 7 Pressure regulating valve The blow-by gasses flow through the opening in the area of the sixth cylinder into the settling cham¬ ber in the cylinder head cover. From the settling chamber, the blow-by gasses are directed through holes on to an impact plate, against which the oil impacts, due to the high flow rate, and flows off. The blow-by gasses cleaned of oil now flow via the pressure control valve and, depending on the operating mode, via the non-return valves into the intake area upstream of the exhaust turbocharger or via the cylinder head ahead of the intake valves. The separated oil is directed via a return flow duct to below the oil level into the oil pan. Function The standard function can only be used as long as a vacuum prevails in the intake air manifold, i.e. in naturally-aspirated engine mode. 17 N55 Engine. 4. Engine mechanical system. With the engine operating in naturally-aspirated mode, the vacuum in the intake air manifold opens the non-return valve in the blow-by duct in the cylinder head cover, thus drawing off blow-by gasses via pressure control valve. At the same time, the vacuum also closes the second non-return valve in the duct to the charge air intake line. The blow-by gasses flow via the distributor rail integrated in the cylinder head cover directly into the intake channels in the cylinder head. 0 0 ( 2 > 0 ^ ^ N a> N55 engine, crankcase ventilation, naturally-aspirated engine mode 18 N55 Engine. 4. Engine mechanical system. Index Description Blow-by gasses can no longer be introduced via this channel as soon as the pressure in the intake air manifold increases. There would otherwise be the danger that the boost pressure could enter the crankcase. A non-return valve in the blow-by channel in the cylinder head cover closes the channel to the intake air manifold, thus protecting the crankcase from excess pressure. The now greater demand for fresh air creates a vacuum in the clean air pipe between the exhaust tur¬ bocharger and intake silencer. This vacuum is sufficient to open the non-return valve and to draw off the blow-by gasses via the pressure control valve. 19 N55 Engine. 4. Engine mechanical system. N55 engine, crankcase ventilation, turbocharged engine mode Index Description A Excess pressure B Vacuum c Exhaust gas D Oil E Blow-by gas 1 Air cleaner 2 Intake manifold 20 N55 Engine. 4. Engine mechanical system. Index Description 3 Perforated plates A If a customer complains about high oil consumption and at the same time the exhaust turbocharger is found to be oiled up, it should not be immediately assumed that the exhaust turbocharger is defective. If the oiling already exists after the introduction of the blow-by gasses then the entire engine should be checked for leaks. Defective gaskets or defective crankshaft seals may be the cause of excessively high blow-by gas throughput. Leaking crankshaft seals can cause an oil consumption of up to 3 1/1000 km. 4.1.4. Oil pan The oil pan is made from an aluminium casting. The oil deflector and the intake pipe to the oil pump are designed as one component. To facilitate attachment to the bedplate, the oil return ducts are de¬ signed such that they extend over the oil deflector. Consequently, the oil return ducts end in the oil sump. 21 N55 Engine. 4. Engine mechanical system. N55 engine, bedplate with oil pump and oil deflector Index Description Oil return ducts, intake side Oil return ducts, exhaust side Oil deflector Intake manifold with oil screen filter Oil pump 3 Bedplate 4.2. Crankshaft drive system 4.2.1. Crankshaft and bearings Crankshaft The crankshaft is designed with optimum weight. At 20.3 kg, the crankshaft in the N55 engine is ap¬ prox. 3 kg lighter than the crankshaft in the N54 engine. The crankshaft is also known as a lightweight crankshaft. The crankshaft is made from cast iron (GGG70). The counterweights are arranged asym¬ metrically. No incremental wheel is installed. The timing chains are mounted by means of an M18 cen¬ tral bolt. 22 N55 Engine. 4. Engine mechanical system. ® ® ® ® © N55 engine, crankshaft Index Description A Counterweights 1 Main bearing journal 7 2 Oil hole from big-end bearing to main bearing 3 Oil hole from main bearing to big-end bearing 4 Big-end bearing journal, cylinder 4 Crankshaft main bearings As on the N54 engine, the main bearings on the crankshaft are designed as two-component bearings free of lead. The thrust bearing is mounted at the fourth bearing position. 4.2.2. Connecting rod and bearing The size of the connecting rod of the N55 engine is 144.35 mm. A special feature is the formed hole in the small connecting rod eye. This formed hole optimally distributes the force acting from the piston via the gudgeon pin over the surface of the bush and reduces the load at the edges. 23 N55 Engine. 4. Engine mechanical system. N55 engine, small connecting rod eye Index Description 1 Bush 2 Connecting rod The following graphic shows the surface load on a standard connecting rod without the formed hole. Due to the piston pressure, the force exerted via the gudgeon pin is mainly transmitted to the edges of the bush in the small connecting rod eye. 24 N55 Engine. 4. Engine mechanical system. N54 engine, small connecting rod eye without formed hole Index Description A Low surface load B High surface load When the small connecting rod eye has a formed hole, the force is distributed over a larger area and the load on the edges of the bush is reduced considerably. The force is now spread over a larger area. 25 N55 Engine. 4. Engine mechanical system Index Description A Low surface load B High surface load Lead-free big-end bearing shells are used on the large connecting rod eye. The material G-488 is used on the connecting rod side and the material G-444 on the bearing cap side. The size M9 x 47 connecting rod bolts are the same on the N55 and N54 connecting rod. 4.2.3. Pistons with piston rings A full slipper skirt piston supplied by the company KS is used. The piston diameter is 82.5 mm. The first piston ring is a plain rectangular compression ring with a chrome-ceramic coating on the contact surface. The second piston ring is a tape faced Napier ring. The oil scrape ring is designed as a steel band ring with spring that is also known as VF system. 26 N55 Engine. 4. Engine mechanical system. N55 engine, piston with gudgeon pin and piston rings Index Description 1 Plain rectangular compression ring 2 Taper faced Napier ring 3 VF system ring 4 Steel inlay for first piston ring 5 Groove for first piston ring 6 Groove for second piston ring 7 Groove for oil scraper ring 8 Hole for lubricating oil drain 9 Graphite coating 27 N55 Engine. 4. Engine mechanical system. Combustion chamber geometry The following graphic shows the arrangement of the individual components about the combustion chamber. It can be seen that the BMW (spray-guided) high precision injection (HPI) system is not used but rather a Bosch solenoid valve fuel injector with multi-hole nozzle. The fuel injector is combined with turbocharging and Valvetronic III. For better illustration, a valve with valve set has been removed in the graphic. N55 engine, combustion chamber with components Index Description 1 Valve seat, exhaust valve 2 Exhaust valve 3 Spark plug 4 Fuel injector 5 Intake valve 6 Valve seat, intake valve 4.3. Camshaft drive The camshaft drive corresponds to the camshaft drive on the N54 engine. 28 N55 Engine. 5. Valve gear. 5.1. Design The following graphic shows the design of the cylinder head on the N55 engine with the Valvetronic III and direct fuel injection combination. N55 engine, overview of valve gear in N S o Index Description 1 VANOS unit, intake camshaft 2 VANOS unit, exhaust camshaft 3 Injector well 4 Spark plug well 5 Camshaft housing 6 Valvetronic servomotor 7 Inlet camshaft 8 Torsion spring 9 Gate 10 Eccentric shaft 29 © © © © ® ® 0 N55 Engine. 5. Valve gear. Index Description 11 Intermediate lever 12 Roller lever tappet 13 Valve head 14 Oil spray nozzle 15 Hole for introducing blow-by gas 5.1.1. Camshafts Cast or lightweight camshafts were used simultaneously on the N54 engine. This made it possible to use lightweight camshafts as well as cast camshafts or a mixture of both in an N54 engine. Only lightweight construction camshafts are used on the N55 engine. The lightweight camshafts for the N55 engine are manufactured in an internal high pressure forming process. The exhaust camshaft features bearing races and is encapsulated in a camshaft housing. The camshaft housing reduces oil foaming during operation. N55 engine, assembled camshaft made in an internal high pressure forming process Index Description 1 Shell-shaped cam 2 Corrugated tube 30 N55 Engine. 5. Valve gear. 5.1.2. Valve timing mm N54B3000 N55B30M0 Intake valve 0 [mm] 31.4 32 Exhaust valve 0 [mm] 28 28 Maximum valve lift, intake valve/exhaust valve [mm] 9 . 719.7 9 . 919.7 Intake camshaft spread (VANOS ad¬ justment range) [“crankshaft] 55 70 Exhaust camshaft spread (VANOS ad¬ justment range) [“crankshaft] 45 55 Intake camshaft open¬ ing angle (max.-min. spread) [“crankshaft] 125-70 120-50 Exhaust camshaft opening angle (max.- min. spread) [“crankshaft] 130-85 115-60 Opening period Inlet camshaft [“crankshaft] 245 255 Opening period Exhaust camshaft [“crankshaft] 261 261 31 N55 Engine. 5. Valve gear. 5.1.3. Intake and exhaust valves The valve stem has a diameter of 5 mm on the intake valve and 6 mm on the exhaust valve. The reason for the larger diameter is that the exhaust valve is hollow and is filled with sodium. In addition, the valve seat of the exhaust valve is armoured. 5.1.4. Valve springs The valve springs are different for the intake side and exhaust side. 5.2. Valvetronic 5.2.1. VANOS Overview The VANOS system has been optimised to provide even faster adjustment speeds of the VANOS units. The optimisation has also further reduced the susceptibility to soiling. It can be seen from the following comparison of the VANOS on the N54 engine and the VANOS on the N55 engine that fewer oil channels are required. 32 N55 Engine. 5. Valve gear. N54 engine, VANOS with oil supply Index Description 1 Main oil duct 2 VANOS solenoid valve, intake side 3 VANOS solenoid valve, exhaust side 4 Chain tensioner 5 Return shut-off valve, exhaust side 6 Return shut-off valve, intake side 7 VANOS adjustment unit, exhaust side 8 VANOS adjustment unit, intake side 33 N55 Engine. 5. Valve gear. N55 engine, VANOS with oil supply Index Description 1 Main oil duct 2 VANOS solenoid valve, intake side 3 VANOS solenoid valve, exhaust side 4 Chain tensioner 5 VANOS adjustment unit, exhaust side 6 VANOS adjustment unit, intake side The sensor wheels are now pure deep-drawn sheet metal components and no longer made from two parts. This design increases production accuracy while reducing manufacturing costs. 34 N55 Engine. 5. Valve gear. N55 engine, camshaft sensor wheel Index Description A Rearview B Front view VANOS solenoid valves The return shut-off valve with screen filter used on the N54 engine have now been integrated in the VANOS solenoid valves on the N55 engine. This measure has made it possible to reduce the number of oil ducts in the cylinder head. In addition, the non-return valves have been integrated in the VANOS solenoid valves. Screen filters on the VANOS solenoid valve ensure trouble-free operation and reliably prevent the VANOS solenoid valve from sticking as the result of dirt particles. 5.2.2. Valve list adjustment Overview As can be seen from the following graphic, the installation location of the servomotor has changed. A further feature is that the eccentric shaft sensor is no longer mounted on the eccentric shaft but has been integrated in the servomotor. 35 N55 Engine. 5. Valve gear. N55 engine, valve lift adjustment Index Description 1 Valvetronic servomotor 2 Oil spray nozzle 3 Eccentric shaft 4 Minimum stop 5 Maximum stop The Valvetronic III system is used. The differences between Valvetronic III and Valvetronic II are in the arrangement of the Valvetronic servomotor and the Valvetronic sensor. As in Valvetronic II, the turbu¬ lence level is increased in Valvetronic III for the purpose of optimising the mixture formation with phas¬ ing and masking at the end of the compression cycle. This movement of the cylinder charge improves the combustion during partial load operation and in catalytic converter heating mode. The quench ar¬ eas also contribute to mixture formation. Phasing Phasing results in a lift difference between both intake valves of up to 1.8 mm in the lower partial load range. Consequently, the flow of fresh air is distributed asymmetrically. 36 N55 Engine. 5. Valve gear. Masking Masking refers to the design of the valve seats. This shaping ensures that the incoming fresh air is aligned in such a way as to give rise to the required cylinder charge movement. The advantage of this measure is that the combustion retardation is reduced by approx. 10 “crankshaft. The combustion pro¬ cess takes place faster and a larger valve overlap can be achieved, thus considerably reducing NO x emissions. N55 engine, combustion chamber roof Index Description 37 N55 Engine. 5. Valve gear. The following graphic shows the effect of the previously described measures. These measures achieve improved and faster combustion in the red area. Technically, this is known as the turbulent ki¬ netic energy. Index Description A Valvetronic 1 B Valvetronic II + III with phasing and masking TKE Turbulent kinetic energy Engine response is improved by the combination of Valvetronic III, direct injection and turbocharging. The response up to naturally aspirated full load is shortened on a naturally aspirated engine with Val¬ vetronic as there is now no need wait for the intake air manifold to be filled. The subsequent torque build-up as the turbocharger starts up can be accelerated with the partial lift setting at low engine speed. This effectively flushes out residual gas, thus resulting in faster torque build-up. 38 N55 Engine. 5. Valve gear. N55 engine, valve lift adjustment Index Description 1 Valvetronic servomotor 2 Oil spray nozzle 3 Eccentric shaft 4 Minimum stop 5 Maximum stop Valvetronic A new brushless DC motor is used. The Valvetronic servomotor exhibits the following special features: • Open concept (oil through-flow) • The eccentric shaft angle is determined by angle increments from the integrated sensor sys¬ tem • Power intake reduced by approx. 50 % • Higher actuating dynamics (e.g. cylinder-selective adjustment, idle speed control, etc.) • Weight advantage (approx. 600 gramme) 39 N55 Engine. 5. Valve gear. The third generation Valvetronic servomotor also contains the sensor for determining the position of the eccentric shaft. A further feature of the Valvetronic servomotor is that engine oil flows through and about it. An oil spray nozzle lubricates the worm drive for the eccentric shaft. 200 milliseconds. The Valvetronic servomotor is actuated by a pulse width- modulated signal. The duty cycle is between 5 % and 98 %. 97 N55 Engine. 12. Engine electrical system ® ® ® ® ® ® ® ® • ’ > jt ■ , N55 engine, Valvetronic servomotor Index Description 1 Socket 2 Worm shaft 3 Needle bearing 4 Bearing cover 5 Magnetic sensor wheel 6 Rotor with four magnets 7 Sensor 8 Stator 9 Housing 10 Bearing 98 N55 Engine. 12. Engine electrical system. The DME supplies the sensor with a voltage of 5 Volt. The DME receives signals via five Hall elements and evaluates them. Three of the five Hall sensors are used for rough division and two for fine subdivi¬ sion. In this way, the angle of rotation of the servomotor can be determined to < 7.5°. Together with the step-up ratio of the worm drive, very accurate and fast lift adjustment of the valve can be achieved in this way. 12.4.2. High pressure fuel injection valve The HDEV5.2 used on the N55 engine is a new development based on the HDEV5.1 high pressure fu¬ el injection valve used on the N14 engine. The function is the same. Function The HDEV5.2 is actuated in four phases as shown in the following graphic. 99 N55 Engine. 12. Engine electrical system. © ® j® ■© N55 engine, actuation phases of the HDEV5.2 100 T008-2216 N55 Engine. 12. Engine electrical system Index Description A DME actuation signal B Current flow HDEV5.2 C Voltage at HDEV5.2 1 Booster phase 2 Energisation phase 3 Hold phase 4 Switch off phase 1 Booster phase: Opening of the HDEV5.2 is initiated in the booster phase by a high booster volt¬ age from the DME. The booster phase ends on reaching approx. 10 amps. The high current is achieved by a voltage of up to approx. 65 Volt. 2 Energisation phase: In the energisation phase, the HDEV5.2 is completely opened by control¬ ling the current to approx. 6.2 amps. At the end of the energisation phase, the current is reduced from the energisation to the holding current level of approx. 2.5 amps. 3 Hold phase: The energised HDEV5.2 is kept open by controlling the current at approx. 2.5 amps in the hold phase. 4 Switch off phase: The current is switched off at the end of the injection time in the switch off phase. At least 2 milliseconds elapse between two injection cycles. 101 N55 Engine. 13. Service information. 13.1. Engine mechanical system 13.1.1. Engine casing components Cylinder head A The combination of exhaust turbocharger, Valvetronic and direct fuel injections is referred to as Tur- bo-Valvetronic-Direct-Injection (TVDI). Cylinder head cover A If a customer complains about high oil consumption and at the same time the exhaust turbocharg¬ er is found to be oiled up, it should not be immediately assumed that the exhaust turbocharger is de¬ fective. If the oiling already exists after the introduction of the blow-by gasses then the entire engine should be checked for leaks. Defective gaskets or defective crankshaft seals may be the cause of ex¬ cessively high blow-by gas throughput. Leaking crankshaft seals can cause an oil consumption of up to 3 1/1000 km. 13.2. Fuel conditioning system 13.2.1. Overview Fuel injectors A Work should only be carried out on the fuel system after the engine has cooled down. The coolant temperature must not be more than 40 °C. These requirements must be observed otherwise the resid¬ ual pressure in the high pressure fuel system could cause fuel to spray out. It is essential to observe the utmost cleanliness when working on the high pressure fuel system and follow the working procedures described in the repair instructions. Even minute soiling and damage at the screw connections of the high pressure lines could cause leaks. Particular care must be taken when working on the fuel system of the N55 engine to ensure that the ignition coils are not soiled with fuel. The resistance of the silicone material is greatly reduced by con¬ tact with fuel. This could result in sparkover at the top of the spark plug and misfiring. 102 N55 Engine. 13. Service information. Before working on the fuel system, remove the ignition coils and use a rag to prevent fuel en¬ tering the spark plug well. The ignition coils must be removed before installing new solenoid valve fuel injectors and ut¬ most cleanliness must be observed. Ignition coils that have been heavily soiled with fuel must be replaced. 13.3. Engine electrical system 13.3.1. Ignition coil and spark plug Ignition coil A The ignition voltage of the secondary coil on the N43 and N53 engines is reversed. This is achieved by reverse actuation and a diode in the secondary circuit. The positive polarisation extends spark propa¬ gation, thus improving the flammability of the mixture. This feature is only required in stratified charge mode. Since the air/fuel mixture is homogeneous on the N55 engine, the ’’normal” ignition coil is used. 103 Bayerische Motorenwerke Aktiengesellschaft Handlerqualifizierung und Training RontgenstraBe 7 85716 UnterschleiBheim, Germany