BMW N55 User Manual

Revision Date:
N55 Engine
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Engine Components/Systems Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Te c h n i c a l Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Full Load Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Current Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Engine Designation and Engine Identification . . . . . . . . . . . . . . . . . . . . .11
Engine Designation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Breakdown of N55 Engine Designation . . . . . . . . . . . . . . . . . . . . . . . .12
Engine Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Engine Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Engine Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Engine Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Crankcase and Bedplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Crankshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Crankshaft Main Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Pistons and Rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Connecting Rod and Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Oil Pan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Electrionic Volume-controlled Oil Pump . . . . . . . . . . . . . . . . . . . . . . . . . .23
Oil Pump and Pressure Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Oil Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Oil Filtration and Oil Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Oil Spray Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Oil Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Oil Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Oil Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Cylinder Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Cylinder Head Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Crankcase Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Naturally Aspirated Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Boost Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Valvetrain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Intake and Exhaust Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Valve Springs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Subject Page
Table of Contents
Initial Print Date: 02/10

BMW N55 Specifications

General

Compression Ratio	10.2:1
Redline	7, 000 rpm
Fuel System	Direct injection
Engine Block Material	Aluminum
Cylinder Head Material	Aluminum
Fuel Type	Premium Unleaded
Displacement	3.0 L (2, 979 cc)
Bore x Stroke	84.0 mm x 89.6 mm (3.31 in x 3.53 in)
Turbocharger	Twin-scroll turbocharger
Valvetrain	DOHC, variable valve timing (VANOS)
Oil Capacity	6.5 L (6.9 US qt)
Cooling System	Liquid-cooled
Torque	300-330 lb-ft (407-447 Nm)
Maximum Torque	300-330 lb-ft (407-447 Nm)

Summary

Introduction to the N55 Engine

N55 Engine Components Overview

Crankcase, Crankshaft, Pistons, and Cylinder Head

Overview of N55 crankcase, crankshaft, pistons, cylinder head, and their key features.

VANOS, Valvetrain, and Servomotor Systems

Details on N55 VANOS, Valvetronic III valvetrain, and servomotor integration.

N55 Engine Technical Data and Identification

Technical Specifications and Performance Diagrams

N55 engine specifications, performance curves, model variants, and designation.

Engine Designation and Identification Explained

Breakdown of N55 engine designation codes and identification methods.

Detailed N55 Engine Components - Part 1

Engine Housing, Crankshaft, and Oil System

Details on N55 engine housing, crankshaft, oil pan, oil pump, and supply.

Pistons, Connecting Rods, and Oil Cooling

N55 pistons, connecting rods, oil cooling, and related passages.

Cylinder Head and Crankcase Ventilation

N55 cylinder head, cover, and crankcase ventilation system operation.

Valvetrain and Camshafts

N55 valvetrain, camshafts, valve timing, and lift adjustment overview.

Detailed N55 Engine Components - Part 2

VANOS and Valvetronic III Systems

Details on N55 VANOS system, solenoid valves, and Valvetronic III functionality.

Combustion Chamber and Air Intake Systems

N55 combustion chamber geometry, air intake system, and manifold.

Exhaust, Turbocharger, and Vacuum Systems

N55 air intake, exhaust, turbocharger, catalytic converter, and vacuum systems.

Fuel Injection and Cooling Systems

N55 fuel injection, pressure systems, injectors, and cooling system details.

N55 Engine Electrical System

DME Module and Circuit Diagrams

N55 engine-mounted DME, wiring, and circuit diagrams for electrical systems.

Engine Cooling Electrical System

Electrical schematic for controlling the N55 engine cooling system components.

N55 Engine Functions, Sensors, and Protection

Engine Functions: Fuel, Boost, and Cooling

N55 fuel supply, boost control, and engine cooling temperature management.

Sensors and System Protection

N55 sensors (crankshaft, oil pressure, oxygen) and system protection measures.

Service Information and Coil Precautions

N55 ignition coils, service info, fuel injector precautions, and sensor details.