SIDE NEWS ABOUT N55 BMW ENGINE

Discussion On : System Operation

Basic Operation of The System

BMW’s new N55 engine family’s 306 horsepower and 400Nm power and torque output figures reminds us of the original moment when BMW first announced it was bringing back forced induction into the BMW engine line-up. The N54 engine was factory rated to put out that exact same amount, and it did that via the use of gasoline direct injection and two turbochargers running together, fed gas from three cylinders each.

Three years later, we still have 306 horsepower and 400Nm of torque, but BMW has achieved it using only one turbocharger instead of two. The new N55B30 engine also churns out peak boost and torque faster than the N54, with 400Nm hit at the 1,200rpm point instead of the N54B30′s 1,3000rpm mark.

ENGINE BMW N55

                                   

TWIN SCROLL

The single turbocharger uses twin scroll technology. The twin scroll turbine housing uses dual side by side exhaust gas inlets into the housing, fed by two sources of exhaust pulses. A single path is also not able to take advantage of all the exhaust gas pulses effectively. Since there are two passages, each has a smaller overall volume than a single scroll turbo path, thus the exhaust velocity of each pulse can be maintained.

The N55B30 is not the first BMW engine to use a twin scroll turbocharger, as the BMW Prince engine in the MINI Cooper S also uses one. In the Cooper S, the turbocharger’s twin-scroll principle is fed by two sets of two cylinders each, while in this N55 inline-6 engine it is two groups of 3 cylinders each.

The N54 did not feature valvetronic because in a turbocharged engine, throttle losses can be countered by the positive pressure of the turbocharged air being blown into the engine. But the main reason there was no Valvetronic is because the complexity of designing a cylinder head that could fit Valvetronic mechanisms as well as direct injection. It is because of this reason that the N53 normally asp 

BMW engineers probably finally managed to cram all that technology into the engine and make it possible for them to work all together. The new N55B30 has both a new generation Valvetronic variable valve management system and High Pressure Injection (direct injection at up to 200 bar). Valvetronic replaces the throttle butterfly functions with a control unit infinitely varying the valve stroke on the intake valves. This means the intake is not obstructed by a partially closed throttle during low load operations. The new N55 also features a map-controlled oil pump which takes up less energy, which BMW says is a first in a turbocharged engine.

One of the variations of the Volkswagen EA888 engine also features variable valve management combined with direct injection but the EA888′s valvelift system is only fitted on the exhaust valves of the engine and works in two stages – a high cam and a low cam, unlike Valvetronic which is continuously variable.

Fitted in the newly unveiled BMW 353GT, the new N55B30 engine takes the machine from 0 to 100km/h in just 6.3 seconds, up to a top speed of 250km/h.

irated direct injection engines also do not feature Valvetronic.

VALVETRONIC FOR BMW N55

                                             

Discussion On : Component Identification

Component Identification

 Engine housing:-

·         Engine block ( crankcase and bedplate )

·         Cylinder head

·         Cylinder head cover

·         Oil pan

·         Gasket

                                   

Engine block :-

·         Made from an aluminium die-casting

·         Consist of the crankcase and bedplate.

Crankcase and bedplate :-

·         Crankcase feature cast iron cylinder liners

·         Webs between two cylinders on the deck on the block have a grooved cooling passage.

·         Coolant flow along the grooves from one side of the crankcase to the other, thus enhancing cooling of these area.

·         Five oil return ducts on the exhaust side

·         Five oil return ducts on the intake side

NO	EXPLAINATION
1	COOLING DUCT
2	CYLINDER LINER
3	GROOVED COOLING PASSAGE
4	OIL RETURN DUCT, EXHAUST SIDE
5	OIL RETURN DUCT, RETURN SIDE

Crankshaft :-

·         Lightweight design, at 20.3 kg

·         Approximately 3 kg lighter than the crankshaft in N54 engine

·         Made of cast iron ( GGG70 )

·         No incremental wheel installed on the crankshaft

·         Counterweight are arranged asymmetrically

NO.	EXPLAINATION
A	COUNTERWEIGHT
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

Pistons and rings :-

·         A full slipper skirt piston with a diameter of 82.5 mm.

·         1^st piston ring- plain rectangular compression ring with a chrome-ceramic coating on the contact surface

·         2^nd piston ring- is a tapered faced Napier type ring

·         Oil scrape ring- designed as a steel band ring with spring that is also known as VF system

NO	EXPLAINATION
1	PLAIN RECTANGULAR COMPRESSION RING
2	TAPERED 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 LUBRICANT OIL DRAIN
9	GRAPHITE COATING

Connecting Road and Bearing :-

·         Size – 144.35 mm

·         New features is the specially formed hole in the small end of the connecting road.

·         This formed hole is machined wider on the lower edges of the wrist pin bushing / bore

 

NO	EXPLAINATION
1	BUSHING
2	CONNECTING ROAD

Oil pan :-

·         Made up of aluminium casting

·         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 designed so that they extend over the oil deflector.

NO	EXPLAINATION
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

Introduction to Engine Operation : (Definition of the system) part 2

ii) Locations of the systems in vehicles

The automobile layout describes where on the vehicle the engine and drive wheels are found. 
Many different combinations of engine location and driven wheels are found in practice, and the location of each is dependent on the application the vehicle will be used for. 
Factors influencing the design choice include cost, complexity, reliability, packaging (location and size of the passenger compartment and boot), weight distribution and the vehicle's intended handling characteristics.

4 types of Engine layout :
1) Front Engine Front Drive (FF)
2) Front Engine Rear Drive (FR)
3) Midship Engine Rear Drive (MR)
4) Rear Engine Rear Drive (RR)

source : wikipedia

Introduction to Engine Operation : (Definition of the system)

i) Definition of the Systems

An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion.

The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion apply direct force to some component of the engine. This force is applied typically to pistons, turbine blades, or a nozzle. This force moves the component over a distance, transforming chemical energy into useful mechanical energy.

The term internal combustion engine usually refers to an engine in which combustion is intermittent, such as the more familiar four-stroke and two-stroke piston engines, along with variants, such as the six-stroke piston engine and the Wankel rotary engine.

Operation of Four Stroke Engine

Four-stroke internal combustion engines have four basic steps that repeat with every two revolutions of the engine:
(1) Intake stroke 
(2) Compression stroke 
(3) Power stroke and 
(4) Exhaust stroke

1. Intake stroke: The first stroke of the internal combustion engine is also known as the suction stroke because the piston moves to the maximum volume position (downward direction in the cylinder). The inlet valve opens as a result of the cam lobe pressing down on the valve stem, and the vaporized fuel mixture enters the combustion chamber. The inlet valve closes at the end of this stroke.

2. Compression stroke: In this stroke, both valves are closed and the piston starts its movement to the minimum volume position (upward direction in the cylinder) and compresses the fuel mixture. During the compression process, pressure, temperature and the density of the fuel mixture increases.

3. A Power stroke: When the piston reaches a point just before top dead center, the spark plug ignites the fuel mixture. The point at which the fuel ignites varies by engine; typically it is about 10 degrees before top dead center. This expansion of gases caused by ignition of the fuel produces the power that is transmitted to the crank shaft mechanism.

4. Exhaust stroke: In the end of the power stroke, the exhaust valve opens. During this stroke, the piston starts its movement in the maximum volume position. The open exhaust valve allows the exhaust gases to escape the cylinder. At the end of this stroke, the exhaust valve closes, the inlet valve opens, and the sequence repeats in the next cycle.

Operation of Wankel Engine

The Wankel engine (rotary engine) does not have piston strokes. It operates with the same separation of phases as the four-stroke engine with the phases taking place in separate locations in the engine. In thermodynamic terms it follows the Otto engine cycle, so may be thought of as a "four-phase" engine. While it is true that three power strokes typically occur per rotor revolution due to the 3:1 revolution ratio of the rotor to the eccentric shaft, only one power stroke per shaft revolution actually occurs; this engine provides three power 'strokes' per revolution per rotor giving it a greater power-to-weight ratio than piston engines. This type of engine was most notably used in the Mazda RX-8, the earlier RX-7, and other models.

Mazda RX-8 Wankel Engine

source : wikipedia

Common Types of Engine

- Singles : typically used in motorbikes, snowblowers, chainsaws etc.

- V-twins : found in motorbikes.

- The triple : almost unique to Triumph motorbikes where they call it the

Speed Triple, or the 675.

- Straight 4/Inline-fours : the mainstay of car engines, as well as being found in

some motorbikes too such as the BMW K1200S.

- Straight 5/Inline fives : used a lot in Audi but have found a new home in

current Volvo.

- The V5 : find in some Volkswagen.

- The V6 : has the benefits of being smoother than an inline-four but without

the fuel economy issues of a V8.

- Boxer engines : found in BMW motorbikes (twins), Porsche and

Subaru (fours and sixes).

source : http://www.carbibles.com/fuel_engine_bible.html

(...will continue on Location of the system in vehicle in the next post...)