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BMW's New Six-Cylinder Engines - In Depth
Text & photos courtesy BMW AG
Page 1 - BMW engines enter a new era
Page 2 - The most innovative power unit of our time
Page 3 - BMW uses magnesium in high-volume production
Page 4 - Second-generation VALVETRONIC
Page 5 - World premiere of the electric water pump and further innovations
Page 6 - Specifications and torque charts
Page 7 - The use of magnesium in engine construction
Page 8 - History of the BMW inline six-cylinder petrol engine
Page 9 - Innovative Variable Twin Turbo technology
Page 10 - Premiere of 535d Saloon and 535d Touring
Page 11 - Efficient dynamics: the technology of driving pleasure
Page 12 - BMW engine production plant in Steyr
BMW engines enter a new era
The BMW Group enters new dimensions.
“We will keep our foot on the accelerator pedal, we will continue to forge ahead.” With these words Dr. Helmut Panke, chief executive of the BMW AG, proclaimed at this year’s Annual Accounts Press Conference in which direction the Bavarian premium manufacturer is moving – “straight ahead”, as usual. New series, new models and the opening up of new markets – BMW has impressively underlined over recent years that when it comes to the brand with the white and blue badge, actions speak louder than words. In 2003, BMW achieved the highest sales figures ever, the number of vehicles sold reaching 928,151.
The inline six-cylinder engine.
When speaking of acceleration, Dr. Panke is not referring to just a short spurt, but “the lasting accomplishment of a higher speed”. In aspiring to do this, a premium manufacturer requires the appropriate premium engines. Superior technology has rendered BMW the leading producer of power units.
BMW regularly receives the annual “International Engine of the World Award”, BMW has initiated advancements in engine construction with the introduction of innovations such as VANOS and VALVETRONIC, successfully establishing them on the market.
For 71 years now the inline six engine has served as a basis of driving pleasure. And there is no reason to break with this tradition, a tradition that is probably unique in the field of engine construction. This is due above all to the fact that it is based on a proven physical principle (no free inertia forces and moments). Today more than half of all BMW automobiles are powered by either an inline six petrol engine or a diesel engine. Consequently, BMW is the world’s largest manufacturer of inline six power units for automobiles.
Optimum balance of masses, silky-smooth turbine-like running characteristics, fast-revving – ideal genes, pioneering innovations, high performance, low fuel consumption and the engineers’ constant meticulous attention to detail have optimized the BMW inline six engine and rendered it an icon. The principle of consistent innovation to raise its own standards has placed BMW in a pole position in technology, not only in the field of engine construction, but also as a carmaker as a whole.
The concept of efficient dynamics.
The BMW designers’ main conflict of objectives arises from the customer’s desire for more power, comfort and safety on the one hand and from the equally understandable desire for lower fuel consumption and reduced exhaust emission on the other: BMW subsumes this issue under the term efficient dynamics, and understands this as being considerably more than the mere improvement of a few test values. Consequently, BMW interprets the term dynamics as the general behaviour of the vehicle, as its performance offered to the customer as a part of the driving experience. Efficiency is equally as comprehensive, this being the overall ratio between input and output, including, for example, “on demand” and “just in time” production, as well as the sensible use of resources. It is particularly crucial to BMW that efficiency should not belittle dynamics – and vice versa.
Technology leader BMW forges ahead: engine construction reconceived.
Due to its specific location in the vehicle and its concentrated mass, BMW designers focus predominantly on the power unit when it comes to discussing efficient dynamics, weight and the distribution of weight in the vehicle within the framework of the concept. And this is precisely the point at which emotions are sparked among engineers, as the BMW power unit is not only a splendid example of technology, but also a matter of inner attitude. Hence the new challenges were taken up passionately. This resulted in the creation of typical BMW high-tech power units that fundamentally question previously known concepts and countless details – and respond with innovative, trendsetting solutions.
In the 75th year of the BMW automobile and 71 years after the first BMW inline six engine, BMW is taking a giant and fundamental step into the future of engine construction. BMW has radically reconceived both the internal combustion engine and the diesel engine, taking the BMW inline six power unit into a new era.
The BMW inline six-cylinder petrol engine with magnesium alloy crankcase and VALVETRONIC
BMW power unit of the future: new standards in specific power output, weight and fuel consumption.
World premiere: composite magnesium/aluminium as revolutionary material technology for lightweight crankcase construction.
Electric water pump and further BMW innovations for systems, components and aggregates in the largest ever BMW engine project.
With the implementation of the most comprehensive engine project since the introduction of the first BMW automobile, the German premium carmaker is presenting its new 3.0 litre inline six internal combustion engine (R6) – a high-tech power unit with a composite magnesium/aluminium crankcase, VALVETRONIC and a myriad of further innovations. With 63 kW/ltr and 1.18 kW/kg respectively, the basic BMW power unit of the future has the highest specific power output per litre and the lowest weight per horsepower in its class. Weighing in at just 161 kg, the new R6 is 7 percent lighter than its predecessor, making it the world’s lightest six-cylinder engine. Power output is up by 12 percent to 190 kW/258 bhp, with fuel consumption down by 12 percent.
The most innovative power unit of our time:
An engine blessed for success.
The inline six-cylinder engine used up until now has been an extremely successful power unit – sporty, economical, smooth-running with an earthy exhaust sound. A total of 1.4 million have already been built. And weighing just 171 kg, the M54 is also one of the world’s lightest six-cylinder engines.
Further development conceivable but inefficient.
Consequently, the previous engine would have been an ideal candidate for further evolutionary development, which had happened consistently and through which the BMW basic power unit had achieved its cult status and its pole position in the market.
However, BMW customer demands on a new engine, ambitious objectives in regard to performance and the reduction of fuel consumption, as well as standards set by BMW engineers in innovative engine construction were reason enough for an entirely new concept – the R6. This decision is impressively underlined by the specifications of the redeveloped power unit. An upgrade of the existing unit according to state-of-the-art technical specifications would have resulted, inter alia, in the engine being 14 kg heavier. After several technical modifications to the M54, which consistently increased performance, bringing about a drop in fuel consumption at the same time, the demands of the future could only be fulfilled by implementing fundamentally new concepts offering a high technological potential. It then became evident that the new engine had to be radically modified, leaving only the principle of an inline six-cylinder arrangement unchanged.
A look at the specifications:
Conflicting objectives can only be solved using new technologies.
In view of the high standards set at BMW, new developments have to take a particularly giant leap into the future. Initially, the basic requirements placed on every BMW engine are increased output and higher torque on the crankshaft. However, at the same time, both fuel consumption and CO2 emissions have to be lowered.
Moreover, on a medium-term basis, BMW innovations pertaining to an individual component or aggregate become the technological benchmark of the entire company and its products, spanning all series, markets and client groups. The BMW innovation VALVETRONIC, for instance, is already featured on all BMW four-, eight- and twelve-cylinder power units. For this reason it was only natural to apply this technology to the six-cylinder engine. However, at the same time, the power unit had to retain its weight and size.
Optimum power density could only be realized through the utilization of new technologies and materials, incorporating a modified basic design and a myriad of innovations for systems, ancillary units and components.
Higher output, lower fuel consumption, maximum power density: Basic R6 power unit and variants for many new BMW models.
In its role as the new BMW basic power unit, the R6 distinctly surpasses the final version of its predecessor in every aspect, thus emphasizing BMW’s pole position in the development and production of sporty and particularly powerful engines.
BMW’s medium-term corporate plans reveal that around half of all new BMW cars will in future be powered by a new R6. The innovative technologies utilized within the new family of R6 engines will secure BMW’s lead in the field of markedly sporty and technically innovative vehicles featuring a uniquely smooth-running, exclusive and efficient power unit.
BMW’s corporate objective is to build fascinating and highly emotional automobiles. In achieving this goal, the main focus of interest is on technology. Nevertheless, the high technological standard at BMW has to be constantly redefined, rendering innovations indispensable. Consequently, when designing the R6, priority was given to the ongoing development of typical BMW qualities such as dynamics, agility, efficiency and superiority, with balanced emphasis on all relevant parameters and with the purpose of reaching as large a target group as possible.
The new BMW 3.0 litre inline six-cylinder engine offers the highest specific output, the best power-to-weight ratio and the lowest specific fuel consumption in its class.
With 190 kW/258 bhp at 6,650 rpm, the R6 surpasses its predecessor by 20 kW/27 bhp. The maximum torque of 300 Nm, up until now a peak value at 3,500 rpm, is now consistently available between 2,500 and 4,000 rpm. Specific output is up by 12 percent from 57 kW per litre cubic capacity to 63 kW per litre. The weight of the engine has been reduced by 10 kg (–7%) to 161 kg. Due to increased output and weight reduction, the power-to-weight ratio exceeds the 1 kW/kg mark by an incredible18 percent. The R6 delivers 1.18 kW/kg (as opposed to 0.99 kW/kg in the case of its predecessor). Fuel consumption is down by 12 percent.
Milestone in lightweight engine construction: BMW uses magnesium in high-volume production
For the first time in the history of modern engine construction, BMW is using magnesium in the mass production of a water-cooled crankcase as well as for the new bedplate and cylinder-head cover. The 7 percent reduction in engine weight (10 kg) resulting from this and from numerous other measures contributes substantially towards a further increase in the agility and dynamics of BMW automobiles.
The extraordinary weight advantage achieved by the use of magnesium is a result of the density of this innovative material. In its pure form, magnesium is around 30 percent lighter than aluminium (density of aluminium 2.68 grams/ cubic centimetre, magnesium 1.81 grams/ cubic centimetre, steel 7.87 grams/ cubic centimetre).
The revolutionary use of composite magnesium/aluminium technology is a milestone in engine construction. It is a conclusive element in a series of innovations in the field of lightweight construction featured in BMW automobiles and a contribution that points the way ahead to a higher technological standard that is a distinctive mark of the company as a whole.
Efficient dynamics – this stands for the realization of driving pleasure for discerning target groups, giving consideration to prevailing present-day technological and social conditions. Within the framework of this long-term BMW concept, a reduction in the weight of the R6 as a means of enhancing driving pleasure was of prime importance in its development.
More powerful, more economical, lighter. BMW R6 – better in every respect. Optimum value of 1.18 kW/kg. 10 kg lighter than its predecessor.
New material technologies such as composite magnesium/aluminium, lightweight exhaust manifolds and camshafts result in the R6 having a weight advantage of 10 kg compared to its predecessor – notwithstanding the increase in output and a drop in fuel consumption attained by the use of VALVETRONIC.
With the engine delivering 1.18 kW/kg, the R6 sets new standards in terms of power density. The new BMW engine has a total weight of 161 kg, making it the world’s lightest six-cylinder in this performance category. The innovative R6 also sets the new benchmark in terms of power output, fuel consumption, running-smoothness, performance and the utilization of innovative technologies. Thus, this basic engine construction also forms a solid basis for a future-orientated six-cylinder series.
The world’s first composite magnesium/aluminium crankcase.
The crankcase featured in the new 3.0 litre internal combustion engine is by far the lightest six-cylinder crankcase used in large-scale production. Being the largest single engine component, it makes a significant contribution to reducing the weight of the R6 by a total of 10 kg compared to the previous version. The new composite magnesium/aluminium crankcase weighs just 57 percent of a comparable grey-cast iron block, the weight advantage in comparison to an aluminium crankcase being 24 percent.
Apart from using magnesium for the first time in this form, BMW specialists also achieved a technological breakthrough in terms of its use in the crankcase. Only the combination of a magnesium shell and an aluminium insert now used fulfils the stringent demands on stiffness, acoustics and durability. Consequently, BMW is the first manufacturer of a water-cooled internal combustion engine to make use of the considerable weight advantage offered by magnesium and to overcome the disadvantages posed by light metal.
A crankcase made exclusively of pure magnesium or a conventional magnesium alloy is inadequate for high-performance engines produced in series. It has insufficient stability and the surface structure of magnesium is unsuitable for the cylinder liners.
Aluminium insert on the inside, magnesium shell on the outside. Reduction in components and assembly work.
The inner part of the crankcase featured by the R6, the aluminium insert, incorporates the cylinder liners and the coolant ducts in the area of the engine block. The insert provides for the required stability under the high thermal and mechanical strain the engine is subjected to. The cylinder head is mounted directly onto the insert, the lower section of the latter serving as the upper section of the crankshaft mounting.
The magnesium jacket is placed into position over the entire insert and sealed tightly. The former consists of a single recast part and accommodates the oil ducts as well as most mounts and brackets for ancillary components. This results in a reduction in parts, weight and assembly work required in these areas. At the same time the integration of supports and brackets increases stiffness of the ancillary component connection. This in turn enhances the acoustics of the crankcase and the ancillary component connections as a whole.
Additionally, the gear casing is integrated in the magnesium housing. During the engine assembly process the entire chain drive is simply placed into the chain chamber at the front end of the engine and fixed into position. Gear casing bolts and the time-consuming task of sealing the cylinder head and the crankcase are rendered completely unnecessary.
From motor sport to series production.
Magnesium bedplate as a load-bearing engine component.
The magnesium bedplate is part of the new R6's central frame structure. For this reason it is relatively solid and is, likewise, a composite construction.
The bedplate guarantees the highest level of structural and torsional stiffness as well as optimum fatigue strength of the R6 engine. As the crankcase is split down the middle on the level of the crankshaft bearings, an optimum reduction in vibration is achieved, this resulting in enhanced acoustics.
In order to achieve sporty performance, the top engine speed of the R6 has been raised to 7,000 rpm (+ 500 rpm). So it was only logical that this bedplate, which had been tried and tested under the harsh conditions prevailing in motor sport, should be also used for series production.
The crankcase is mounted on the bedplate from above, together with the upper section of the crankshaft bearing. The lower counterpart of the crankshaft bearing is integrated into the bedplate. The crankshaft runs on sintered steel inserts surrounded by magnesium.
The join between bedplate and crankcase is made tight using a liquid sealant. After bedplate and crankcase have been bolted together, the sealing compound is injected under high pressure into a groove on the contact surface between the two components. The engine mounting brackets are bolted to both bedplate and crankcase.
Magnesium cylinder-head cover.
Following the path of consistent lightweight construction, the cylinder-head cover of the R6 is also made of magnesium.
The use of magnesium in engine construction.
Technology overcomes natural differences.
BMW has successfully managed to overcome the problem of the chemical incompatibility of magnesium and water. The coolant does not come into contact with the magnesium shell of the crankcase as it flows exclusively inside the aluminium insert.
Special aluminium bolts are used for fixing parts to magnesium components, as magnesium and aluminium both have similar coefficients of expansion. Moreover, aluminium bolts make a further contribution towards a radical reduction in engine weight. The similar reaction of magnesium and aluminium at melting point is also a crucial quality aspect when casting magnesium around the aluminium insert.
The world’s first six-cylinder to feature VALVETRONIC
Completion of implementation in all engine series.
After successfully featuring VALVETRONIC on four-, eight-, and twelve-cylinder power units, this BMW-exclusive technology is now being implemented in the case of the inline six-cylinder. The BMW innovation VALVETRONIC adjusts the valve opening times and the valve timing infinitely and according to the position of the accelerator pedal. This technology eliminates the need for throttle butterflies and very accurately regulates charge changing processes, thereby achieving particularly efficient fuel economy and a distinctively improved engine response.
VALVETRONIC is also an example of how BMW sets its own technical standard by the use of advanced technologies. BMW had first introduced VALVETRONIC in the year 2001 for the four-cylinder engine. Since then this internationally acclaimed BMW patent has been successively featured in other engine series.
Fast-revving sporty performance up to 7,000 rpm (+ 500 rpm).
The new BMW R6 is the first engine to feature BMW second-generation VALVETRONIC.
Engines with sporting characteristics excel due to higher engine speeds and particularly fast revving. In the ongoing development of this feature, which is equally as crucial to BMW as output, weight and fuel consumption, the rated engine speed was increased and maximum engine speed was raised to 7,000 rpm. As a result, the R6 has introduced a new class of mass-produced engines of this size.
This is made possible by second-generation VALVETRONIC, which excels through distinctively enhanced constructional stiffness. Consequently, the valve actuation of the R6 achieves acceleration ratings equal to those produced by bucket tappet valve trains.
VALVETRONIC is, therefore, moving in the direction of higher engine speeds, a fact that will most definitely appeal to the more sport-orientated customer. On the other hand, the R6 with second-generation VALVETRONIC will provide for more efficiency in achieving enhanced dynamic driving pleasure.
For the first time, the VANOS throttle butterflies incorporated into the VALVETRONIC are made entirely of aluminium. Thus, for the very first time, the chain wheel on the timing device is likewise made of this light metal, thereby contributing towards a further reduction in weight.
VALVETRONIC well represented in the marketplace.
Distinctly more successful than lean direct injection concepts.
With the introduction of the second generation, VALVELTRONIC is now the technical standard on all BMW petrol engines. Employing it in the six-cylinder, the most widely sold BMW power unit, also means a quantum leap for this innovative technology’s market penetration and the overall reduction in fuel consumption achieved by this technology.
In this context, VALVETRONIC is also compared with lean direct injection systems, which for very good reasons BMW is not currently offering: Lean DI systems can, for example, only exploit their full fuel consumption potential when using sulphur-free petrol. However, there are insufficient supplies of this type of fuel and it is not available in some countries at all – as was precisely the case with unleaded petrol when vehicles were first equipped with catalytic converters.
Customers seem to agree with BMW, as VALVETRONIC is well accepted throughout the world. For example, since introducing this new technology, BMW has already sold hundreds of thousands of automobiles worldwide with engines featuring VALVETRONIC, whereas only a few thousand vehicles featuring lean direct injection systems were sold by other carmakers over the same period.
Economical, spontaneous, exclusive.
BMW patent VALVETRONIC replaces the throttle valve function.
VALVETRONIC removes the need for a throttle butterfly and regulates engine performance by means of infinitely variable valve timing. Engine performance used to be regulated by a throttle valve, which, as the term implies, controlled engine performance by throttling air intake; a somewhat inefficient method.
In the case of the BMW innovation VALVETRONIC, valve opening times and valve timing are controlled according to the current position of the accelerator pedal, thus minimising the cylinder charge flow losses. Utilizing this method of throttle-free load control, VALVETRONIC reduces fuel consumption and ensures a significantly improved engine response.
This process is controlled according to the position of the accelerator pedal. Adjustments are made via a central servomotor, an eccentric shaft and an intermediate lever. VALVETRONIC is based to a great extent on the tried and tested, likewise infinitely variable BMW bi-VANOS (variable camshaft control).
On average and under all operating conditions, VALVETRONIC achieves a drop in fuel consumption of 10 percent in the composite EU cycle. VALVETRONIC operates independently of fuel and oil grades. With the introduction of the R6, BMW has made VALVETRONIC available to all petrol engines, all models and all markets. VALVETRONIC systems are manufactured exclusively at BMW’s own plants according to BMW’s own patent.
Apart from increasing efficiency to a great extent, VALVETRONIC technology is responsible for an increase in dynamics. The accurate and direct conversion of accelerator pedal commands into engine performance and acceleration, and the absence of idle time while the air plenum is being filled and emptied, offers the driver of a BMW considerably enhanced driving dynamics and vehicle spontaneity. In this respect VALVETRONIC is almost equally as effective as solutions with individual throttle butterflies.
BMW innovation: world premiere of the electric water pump
Independence from engine speed, reduction in consumption.
For the transportation of water within the cooling system BMW employs the world’s first electric pump. It operates absolutely autonomously and is controlled entirely according to the engine’s actual cooling requirement, irrespective of the current engine speed.
With the electric water pump BMW achieves a remarkable reduction in consumption. A conventional water pump consumes up to 2 kW, whilst the new BMW system has a maximum power consumption of just 200 W. Even in the particularly uneconomical warm-up phase the electric water pump requires hardly any fuel at all, the coolant heating up very quickly as no cooling is required during this phase, and is therefore not pumped through the system. On the other hand, when the engine is not running, the residual heat in the coolant can be efficiently utilized to heat the car’s interior when required.
The transportation and cooling capacity of a conventional water pump is designed to cope with a maximum engine load at low engine speeds and is, therefore, too large for many operating conditions at high engine speeds. Moreover, they are in permanent operation via the belt drive, with the respective losses due to friction. The flow rate of conventional water pumps is entirely dependent on engine speed and not on the engine’s actual cooling requirement under each prevailing operating condition.
Further innovations and consistent lightweight construction of aggregates and components.
Lightweight camshafts with a weight advantage of 1.2 kg.
With exception of the revolutionary composite aluminium-magnesium crankcase, the new lightweight camshafts are the largest single contributors towards the BMW R6’s remarkably low weight of 161 kg. By means of hydroforming it is possible to reduce the weight of each finished camshaft by 600 g (–25%).
The basic component of the new camshaft is a steel tube that is pulled through the cam rings made of high-strength refined steel. The parts are placed together in a die and the tube is subjected from the inside to a water pressure of 4,000 bar. By this method the tube is brought into the desired wave shape in a cold state and pressed against the cams from the inside. Finally, the cams are accurately polished down to a 1***61549; (1***8725;1000 mm) finish.
Each of these finished camshafts is 600 g lighter than a conventional camshaft. In the case of the R6 with its double overhead camshafts this means that the two camshafts alone enable a 1.2 kg saving in weight. BMW already used hydroforming in car manufacturing when producing the windscreen frame of the latest 3 Series Convertible. BMW further developed this technology, rendering it suitable for processing high precision parts such as camshafts.
Producing cylinder heads by the lost-foam method.
As early as during the initial stage of production – the casting process – the cylinder head of the new engine places particularly high demands on manufacturing technology. Generally speaking, the casting of the cylinder head of the inline six is more sophisticated than any other engine construction method (with the exception of a twelve-cylinder engine with its two lines of cylinders). Due to the overall length, the natural effects of shrinkage are very distinctively noticeable during solidification and cooling down of the aluminium, which is heated to around 700° Celsius. Employees working at the company’s own light metal foundry are uniquely competent in the production of these components – after all, they have been casting cylinder heads for all BMW inline six-cylinder engines since the introduction of aluminium cylinder heads for the petrol engine in the sixties and for the diesel engine in the eighties.
Computer-aided casting process simulations are decisive factors for the successful casting of cylinder-heads. They facilitate prior to production the evaluation of shrinkage processes during the construction of components and moulds, as well as precise control of solidification processes during the casting process through the implementation of appropriate temperature management in the casting mould.
Two parallel casting methods are used in the manufacture of the cylinder- head for the new six-cylinder engine, both of which were tried and tested in the production of the previous generation of engines, and which were further enhanced to meet the specific requirements of the new component. These methods are known as low-pressure casting and lost foam casting. Both methods are particularly suitable for the optimum forming of the complex outer contours, with the integrated cam carrier accommodating the camshaft and the eccentric shaft, as well as the intricate inner contours with cavities for the air ducts and the filigree oil and cooling water circulation systems.
Since first introducing the lost foam method in the production of cylinder heads for BMW inline six engines in 1997, the company’s own light metal foundry has held pole position in the application of this technology designed for the construction of complex engine components. The method has firmly established itself by being applied in the manufacture of the cylinder heads of more than one and a half million six-cylinder engines.
As opposed to conventional casting technology, lost foam casting is a positive moulding method. At the start of the manufacturing process an identical pattern of the cylinder-head using polystyrene is produced. This is done by placing six single layers of foam plastic, commonly used as packing material, into moulds, in which they are foamed up and finally glued together.
The finished polystyrene pattern of the cylinder head is then coated with a ceramic agent, packed in sand, vibrated and completely enclosed in fine-grained casting sand, leaving only a sprue runner free. Molten aluminium is poured into this sprue runner during the automated casting process.
It thereby completely replaces the polystyrene pattern and adopts the shape of the cylinder head. Due to the high precision achieved by this casting method, even particularly filigree constructional details such as oil holes can be integrated simultaneously during casting. This eliminates numerous manufacturing procedures during the subsequent mechanical finishing process.
Permanent customer-friendly solution: valves driven by chain.
In the case of the new R6 engine, BMW continues to give preference to a chain drive of the valves. Firstly, it contributes greatly to an accurate and durable function of the engine. Secondly, it eliminates extensive maintenance work, thereby reducing cost to the customer.
The chain drive is incorporated into the magnesium cast part of the new lightweight crankcase. It is inserted as a module into the gear casing shaft at the front end of the engine. The chain tightener is made entirely of aluminium, adding further to the consistent lightweight construction of the R6.
A shorter, lighter engine: all ancillary components driven by one single belt.
The R6 BMW employs just one single belt to drive all ancillary components. There is no second belt at all, so the engine has a shorter design. At the same time all accessory parts, that is belt, belt pulley and tightener become unnecessary, a further aspect that contributes towards making the R6 the lightest engine in its class. Single belt drive is made possible thanks to the use of the aforementioned electric water pump, which operates without a belt.
Higher torque, lower engine speed:the new three-stage resonance air intake system.
With the three-stage resonance air intake system featured on the R6, BMW achieves a higher torque at lower engine speeds. The new R6 generates its maximum torque of 300 Nm at only 2,500 rpm, which remains constantly on tap up to 4,000 rpm.
The new three-stage resonance air intake system is a further development of the old dual system. By the use of a third resonance pipe, which is actuated via resonance valves, the engine speed range, in which the self-loading effect of the system takes effect, is increased. Each of the three resonance pipes is effective in a clearly defined section of this engine speed band.
Capacity-controlled oil pump: double flow rate, precise control, substantially lower energy consumption.
In accordance with the current oil pressure, the capacity-controlled oil pump accurately supplies the required quantity of oil during each operating condition. As the oil circulation parameters (pressure, quantity and temperature) react partly in opposite ways, conventional pumps, which increase their flow rate according to engine speed, are not suitable for the complex requirements of the new BMW R6.
The whole dimension of the R6 project is aptly demonstrated by one single ancillary component. With the capacity-controlled oil pump BMW achieves two goals simultaneously:
the amount of oil intake corresponds to the quantity required under each particular operating condition. The capacity-controlled oil pump does not require a bybass in order to re-divert excess flow (up to 80%).
Thanks to the regulation of the actual requirement and the elimination of unnecessary output, the capacity-controlled oil pump consumes up to 2 kW less than conventional oil pumps.
Lighter and robust: the trapezoidal connecting rod.
When viewed from the side, the upper eye of the connecting rod is shaped like a trapeze. This new technology is used on the internal combustion engine to taper the conrod eye in its upper area, hence facilitating a saving in weight. Just a few grams on each connecting rod, which, however, make all the difference, considering the high speed at which the connecting rods move up and down inside the engine.
Within the lower area of the connecting rod eye, the entire width is still required for the gudgeon pin in order to transfer the forces to the crankshaft via the connecting rod.
Like all other BMW connecting rods, those installed in the new inline six engine have also undergone the cracking process. This method entails breaking the lower connecting rod eye in two. The two parts are then bolted together again when assembled onto the crankshaft. Due to the uneven surfaces resulting from the cracking process, the link between the two parts of the connecting rod have far greater stability than the even surfaces obtained on conventionally sawn connecting rods.
Shorter warm-up phase, additional oil cooling: Oil/water heat exchanger.
The oil/water heat exchanger transfers heat to the oil circulation during the warm-up phase, as cooling water heats up faster than oil. Consequently, heating of the engine oil is accelerated to such an extent that it reaches operating temperature much earlier, thereby shortening the uneconomical warm-up phase.
In operating conditions resulting in higher engine output and high oil temperatures, heat is extracted from the oil circuit via the oil/water heat exchanger and from the engine via the coolant circuit and the engine cooling system.
Marked overall reduction in the R6 engine’s friction.
In addition to an efficient control of coolant flow due to an electric water pump and of oil flow thanks to a capacity-controlled oil pump, the reduction in friction is a crucial factor in the reduction of fuel consumption. For instance, each cylinder-head element was modified to rolling friction. Thanks to optimisation of the bearing design, friction during crankshaft operation has been reduced.
High temperature resistant lightweight exhaust manifold: conformity with EU4 standards without secondary air.
BMW threw all its know-how into the exhaust manifold of the new inline six-cylinder engine, accomplishing a weight reduction of 0.8 kg in this component alone.
The differing thermal expansion coefficients of aluminium (cylinder-head) and steel (exhaust manifold) necessitate new solutions in this particular area. BMW uses a 2 mm thick, lightweight deep-draw flange (previously 12 mm), and, through the use of a graphite ring on each cylinder, achieves even more significantly improved tightness of the engine’s performance header.
The thin-walled ceramic catalysts are smaller and therefore lighter than they used to be. As a result, they reach their operating temperature and converting rate faster, thereby eliminating the need for secondary air intake.
The use of magnesium in engine construction
BMW develops a magnesium alloy with new properties.
In order to be able to make use of the properties of magnesium employed on the new BMW high-tech power unit in mass production, the company has invested in research and development for many years.
After intensive basic research and in close cooperation with material specialists, the engine development department, the light metal foundry at the BMW Landshut plant and the material supplier, a magnesium alloy was developed that fulfils the specific demands of crankcase construction. This resulted in the redefining of the material’s limits for use and the exploitation of new fields of application.
During development of the material, engineers focussed predominantly on creep resistance, thermal and mechanical capacitance, but also on its casting qualities. Parallel to this, at the die-casting research centre at BMW’s Landshut plant, the necessary competence in casting procedures was acquired and the complex manufacturing process finalised. The know-how required for processing this material and the development of processing methods, as well as the mastering of these, were acquired by the BMW Group itself.
Impressive production technology.
The light-metal foundry at the BMW Landshut plant was faced with huge challenges with regard to the technical feasibility of constructing a composite crankcase. Above all, skill in mastering the differing thermal expansion coefficients of aluminium and magnesium requires a profound understanding of technological processes and the foundry specialists’ entire experience.
During the newly developed die-casting method the magnesium shell shrinks on to the aluminium insert while cooling. At the same time the core is permanently anchored within the magnesium jacket by means of ribs with positive engagement. Due to the similar solidification periods of aluminium and magnesium at a temperature of between 500 and 600 degrees Celsius, highly sophisticated temperature management is required in order to achieve highly accurate heating and cooling of tools and insert.
During the first stage of the automated manufacturing process, a separating agent is applied to the two-piece mould, which weighs almost 60 tons, while it is in the die casting machine. Then the aluminium insert is placed in position and the mould is closed. Finally, the real time-controlled unit compresses the molten magnesium, which has been heated to 700 degrees Celsius, into the remaining cavity of the tool mould within a mere six hundredths of a second and at a pressure of almost 1,000 bar. At this point the two parts of the tool are being held together by a force of around 4,000 tons. Within 10 seconds the metal turns solid. The shrinkage of the magnesium shell, resulting from cooling down and solidification, facilitates a firm bond with the aluminium insert. After just 20 seconds the crankcase is removed by a robot from the mould, degated, and finally undergoes special heat treatment in order to reduce internal tension.
The foundry specialists have also entered unknown territory as far as testing technology is concerned. For example, a special process taken from aviation and astronautics and developed further for use in series production for the first time in this particular field, is applied to ensure optimum bonding of the magnesium/aluminium compound. By means of non-destructive ultrasonic lock-in thermography the crankcase is stimulated by ultrasonic waves using an impulse transmitter. The thermal behaviour of the joining surfaces of the two materials is recorded by means of a highly sensitive thermal imaging camera and automatically evaluated.
For the manufacture of the composite crankcase the BMW Group has invested more than 100 million Euros in the construction of a new extension building for the light metal foundry at the Landshut plant with over 10,000 square metres of floor space. The composite crankcase is manufactured using a total of six highly automated production cells incorporating the most efficient die-casting machines currently in use. This makes the new foundry one of the world’s most modern and largest magnesium foundries.
Significant changes to the manufacturing process compared to all-aluminium components are not necessary, neither in the foundry nor during subsequent machining of the materials, as magnesium is easy to process. For the handling of coolants and lubricants and the disposal of swarf the BMW Group utilises the know-how and many years of experience of respective partners from industry. A material recycling concept has been secured.
Magnesium as a lightweight material –
already used, wherever feasible, for series production.
For many years now the BMW Group has utilized magnesium components wherever feasible. A few examples of its use are the steering wheel skeleton and the steering column support of the BMW 5 and BMW 7 Series, the housing of the fully variable air intake unit of the BMW eight-cylinder engines, the convertible-top compartment cover of the BMW 3 Series Convertible as well as some engine components for BMW motorcycles.
BMW and its power unit portfolio
High competence and long-standing tradition in engine construction
BMW engine construction is as old as the company itself. Since the establishment of the company in 1917, BMW had developed and produced aircraft engines featuring 5 to 28 cylinders and up to 4,000 bhp for various purposes. For example, BMW supplied, inter alia, the nine-cylinder radial engine for the legendary Ju 52.
In 1923, BMW also built the R32, the first BMW motorcycle to feature a double-piston engine (494 cm3/8.5 bhp) – a drive concept still used to this day.
Although BMW had already been producing the BMW 3/15 bhp DA 2 – under license from the Austin Seven – since 1929, it was not until 1932 that BMW began building its own car engine. This four-cylinder with a 0.8 litre capacity, lower camshaft and overhead valves delivered 20 bhp and celebrated its premiere in the BMW 3/20.
The history of the BMW inline six-cylinder petrol engine
Concept and basic arrangement.
The production of advanced inline six-cylinder engines has been one of BMW’s core competences for 71 years now. Even in those early days preference was given to the inline six-cylinder type of design. The silky-smooth, turbine-like running characteristics of the engine are unsurpassed to this day and offer a significant contribution towards driving pleasure.
At the same time, BMW power units are extremely compact and light, considering the performance they produce, this having a positive effect on fuel consumption. The legendary, nimble, high-revving qualities of BMW engines and the very large useful speed range are the result of an adequate balance between performance, torque and each particular engine size.
The superb handling and road behaviour of BMW automobiles, which remain neutral even when pushed to their limits, is attributable mainly to the principle of rear-wheel drive. Since 1933, the longitudinally-mounted inline six-cylinder has consistently endorsed this concept, remaining the optimum engine design within its capacity and performance range.
M78: the first six-cylinder engine for a BMW automobile.
After the foundation of BMW in 1917, it took another 16 years before the first BMW car with an inline six-cylinder engine arrived on the market. 1933 saw the debut of the Typ 303, the second car constructed by the BMW company, featuring a 1.2 litre inline six-cylinder engine with a maximum output of 30 bhp at 4,000 rpm. It excelled predominantly through superb running properties which were unprecedented in this vehicle class.
During the years to follow, a series of further six-cylinders based on this engine was developed, some featuring an aluminium cylinder head. Capacity was increased to up to two litres, depending on the demands on performance.
M328: the six-cylinder legend of the thirties.
With the increase of demands in competitive motor sport it also became necessary to increase power output. The result was the M328, the engine boasted by the legendary sports car of 1937. Featuring three downdraft carburettors mounted on the cylinder head, the 2 litre engine developed 80 bhp. This was sufficient to spur the lightweight 328 to over 145 km/h (90 mph), soon making it the epitome of motor sport. BMW even managed to increase the output of competitive car engines to 100 and 110 bhp. However, it was not the engine itself that set the limits to output, but rather the fuel, which was available only with an octane rating of 80. Consequently, the compression ratio was restricted to a maximum of 9.5:1. This limit was not exceeded until the introduction of special racing fuels, the M328 then producing an output of 136 bhp. As early as 1941 BMW engineers carried out tests on this engine with direct injection and three throttle butterflies as an alternative to the carburettor.
M335: the powerful “long-distance runner” for the German Autobahn.
Nevertheless, in order to achieve its high nominal output, the 328 was dependent upon high engine speeds. Maximum output of 80 bhp was developed at around 4,500 rpm, 3,500 rpm being required to obtain maximum torque of 128 Nm. BMW then brought out the M335, a new six-cylinder built for the Typ 335, a large saloon which arrived on the market in 1939.
This 3.5 litre power unit already reached peak torque of 221 Nm at 2,000 rpm. The highest point of the performance curve was at around 3,500 rpm, the six-cylinder then developing 90 bhp. This made it ideal for driving long distances at high speeds on the German Autobahn, which was still very new in those days.
M337: the six-cylinder engine of the BMW 501, the “baroque angel”.
1954 saw the arrival on the market of the 501, which featured a six-cylinder engine and was the first post-war BMW saloon. The power unit bore the designation M337 and delivered a peak output of 65 bhp at 4,400 rpm. For the next stage of development the combustion chamber was optimized, the result being 72 bhp at 4,400 rpm.
M06: Progenitor of a success story.
It was not until 1968 that the completely reconceived inline six-cylinder engine by BMW was born. This power unit, which was installed at a 30 degree angle, was so modern that it became the standard in engine construction for decades – and the driving force for countless victories in motor sport.
A crossflow cylinder head with overhead camshaft, V-shaped overhead valves, a special combustion chamber shape and a forged crankshaft running in seven bearings resulted in excellent running properties. The term “turbine-like running” when referring to the BMW six-cylinder was born.
The M06 was brought out in a 2.5 litre and 2.8 litre version, delivering 150 and 170 bhp respectively. This bought the BMW 2800 an admission ticket to the exclusive 200 km/h club. Consequently, saloons and, above all, coupés sporting the six-cylinder, caused quite a stir at that time.
1971 saw the appearance of two versions of the six-cylinder, which had been upgraded to 3.0 litres. The version with carburettor bore the designation M21 and delivered 180 bhp. However, the highlight was the M20 with the then newly designed electronic injection system, which provided the BMW 3.0Si with an amazing 200 bhp. Following the 2000 tii, the 3.0 litre was the first BMW series produced six-cylinder featuring fuel injection. With the saloon and the subsequently launched 3.0CSi Coupé, BMW created a real stir in the prestigious luxury segment.
M60: Origin of the 3 Series six-cylinder.
After being used exclusively to power luxury class automobiles for many decades, the M60 six-cylinder, later renamed M20, made its debut in the “small car class” in 1977, when BMW introduced the models 320i and 323i. This classic high-performance power unit, developing maximum output from as small a capacity as possible, provided the basis for an evolutionary series of inline six-cylinder engines, which in principle have remained unchanged to this day.
In 1977, BMW had invested 110 million Marks in the development of this new engine series, a gigantic sum of money in those days, resulting, inter alia, in the six-cylinder being produced in far less time than earlier four-cylinders. Above all, however, the designers had created a new standard for the way in which power development was achieved in the BMW 3 Series’ segment. One of Europe’s leading car magazines commented: “The small engine smoothly reaches highest revs almost vibration-free, emitting an earthy six-cylinder sound, but without becoming obtrusive.”
M88: power for the M1.
A year prior to this and under great secrecy, the development of a unique sports car had begun, which was to cause a stir worldwide in 1978 – the BMW M1. The mid-engine coupé was powered by a 3.5 litre inline six, supplying 277 bhp to the rear axle: The engine bearing the designation M88 was based on the mass-produced M06 engine and sported a four-valve cylinder head – an exclusive exception at that particular time. The M88 was tuned for the Procar racing series and upgraded to 490 bhp. Through further optimization and two turbochargers, an output of 850 to 950 bhp was achieved. A road version of the M88 with 286 bhp was produced for the M635 CSi and the M5 from 1983 to 1989.
M102: the turbo catapults the 745i into pole position in performance.
The first 7 Series appeared in 1977 as a sporty alternative within the luxury class. 1979 saw the market launch of the 732i, the world’s first series-produced car with digital engine electronics. The flagship was eventually the 745i, which arrived in 1980 sporting a 252 bhp turbocharged six-cylinder power unit.
M50: with VANOS emphasizing the use of state-of-the-art engine technology.
During 1989, development eventually led to the employment of the M50 engine series in the 520i with four-valve cylinder head, camshaft and valve tappets featuring hydraulic valve play compensation. The year 1992 proved to be a crucial milestone in the development of the M50. With VANOS – this is the abbreviation for the German term “Variable Nockenwellen-Spreizung” (English = variable camshaft control), and for the first time in automotive history, a system went into mass production that facilitated the adjustment of the opening and closing of the inlet camshaft from “late” to “early” and vice versa. Through this change in timing, variations in charge changing processes and combustion can be perfectly adapted to engine speed and load. The positive effects of this system were significantly improved fuel consumption and exhaust behaviour as well as markedly increased torque in the lower speed range.
M52: the first BMW all-aluminium six-cylinder.
During 1994 the previously used grey-cast iron case was replaced by a crankcase with Nikasil coated surfaces, thereby achieving a reduction in weight. Four years later, in 1998, the extensively modified M52 made its debut along with the new 3 Series Saloon. From then on it featured bi-VANOS.
In contrast to the previous, technically more basic version with just two inlet camshaft settings, adjustment was now effected across the entire engine speed range, this also applying to the outlet camshaft. A resonance intake system was introduced, predominantly to further increase torque at lower engine speeds.
M54: the inline six remains the benchmark.
At the turn of the millennium BMW still endorsed the concept of the inline six-cylinder engine. Further extensive modification of the M52 was completed by June 2000. It was given the designation M54 and was initially introduced in a 3.0 litre version delivering 170 kW/231 bhp. In addition to increasing output and torque, the ultimate goal was to exceed prematurely existing D4 and ULEV emission requirements.
The BMW inline six-cylinder diesel engine with Variable Twin Turbo technology
BMW presents the 3.0 litre-high-performance diesel engine with 200 kW/272 bhp
World premiere: Variable Twin Turbo (two-stage turbocharging) featuring successively positioned turbochargers
The most sporty diesel of all time available from the autumn in the 535d and 535d Touring
With the new Variable Twin Turbo technology (two-stage turbocharging) BMW is defining a new performance segment for the diesel engine. The new BMW 3.0 litre inline six-cylinder diesel featuring Variable Twin Turbo technology (R6D) is by far the most powerful diesel engine in its class. 200 kW/272 bhp at 4,400 rpm and 560 Nm at 2,000 rpm (530 Nm as early as 1,500 rpm) set the new benchmark for diesel engines. Running smoothness and comfort remain at the high level typical of BMW, fuel consumption and emissions are exemplary. A diesel particulate filter is included as standard.
BMW innovation – Variable Twin Turbo technology:
Two turbochargers in a complex control loop
In principle, the BMW innovation Variable Twin Turbo technology comprises two different-sized, successively actuated turbochargers. Depending on the currently prevailing engine speed, intake air is compressed by one of the two turbochargers, or by both. This two-stage charging is regulated by specially designed electronics, which in turn controls a system comprising turbine control, compressor bypass and wastegate.
Diesel power enters new dimensions.
The Variable Twin Turbo technology by BMW enters new dimensions. In the dynamic advancement of the diesel engine it stands shoulder to shoulder with unique innovative measures such as direct injection or Common Rail technology.
The increase in output of around 20 percent attained by the use of Variable Twin Turbo technology when compared with state-of-the-art diesel engines, greatly exceeds that of earlier single-stage technology. At the same time the typical characteristic of Variable Twin Turbo technology increases the useful speed range by providing above-average torque. All in all, diesels featuring Variable Twin Turbo technology offer performance normally expected of engines at least one class larger in cubic capacity.
World premiere: BMW presents first series production diesel power unit to feature Variable Twin Turbo technology
BMW inline six-cylinder engine: also an icon for the diesel.
Thanks to their perfectly balanced masses and moments, inline six-cylinders are, physically, ideal engines. BMW has developed and produced inline six-cylinder engines for 71 years now, a diesel version also being available for 21 years. Whether a petrol or diesel version, BMW inline six-cylinders are today synonymous with superior, smooth-running and dynamic engine performance.
Above all, a well balanced package comprising superior performance, agility and technically innovative solutions has facilitated the use of BMW diesel engines to adequately power sports coupés such as the 330Cd as well as large 7 Series Saloons. BMW has been a pacemaker in diesel engine technology, utilizing its entire engineering competence to develop the diesel engine into a premium power unit providing efficiency, dynamics and comfort at the highest level.
Revolution instead of evolution.
High pressure injection with Common Rail, turbocharging and intercooler are today state-of-the-art diesel engine technology. As in the case of the 3.0 six-cylinder petrol engine, BMW engineers found that only a modest degree of further development was possible using the present concept.
The new diesel engine’s specifications did not provide for an increase in output alone. Preference was given to the simultaneous advancement of dynamics and efficiency, standard at BMW, on a long-term basis. Dynamics as an element of the vehicle’s overall performance is, however, synonymous with agility, nimbleness and best possible distribution of axle load. Consequently, these aspects immediately rendered obsolete considerations to achieve “higher output through larger cubic capacity and additional cylinders”, in particular with a view to its employment in the 5 Series. This was all the more applicable from an economical point of view – as we all know, larger engines have higher fuel consumption.
Therefore, after examining various alternatives, specialists at BMW’s Diesel Competence Centre in Steyr (Austria) decided in favour of revolutionary Variable Twin Turbo technology.
BMW forges ahead: with the world’s most powerful six-cylinder diesel engine and the lightest power unit in its performance segment.
With 200kW/272 bhp at 4,400 rpm, the new BMW inline six-cylinder diesel featuring Variable Twin Turbo technology (R6D) is clearly the world’s most powerful six-cylinder diesel engine available for the motor car. High torque of 530 Nm at 1,500 rpm is developed from the start, a peak value of 560 Nm being reached at 2,000 rpm.
With these impressive figures, the new BMW diesel engine is an absolutely unique high-performance power unit within the 3.0 litre capacity class: It shares pole position alongside established top performers, irrespective of the combustion concept used. Thanks to innovative Variable Twin Turbo technology, BMW is able produce a diesel delivering an output absolutely inconceivable until only just a few years ago.
The autumn of 2004 will see the world premiere of BMW’s Variable Twin Turbo technology when it makes its market debut in the 535d/535d Touring. This will once again affirm the company’s leading position in the development and realization of advanced and highly attractive diesel technology.
The new BMW 3.0 litre diesel engine has the highest specific output of all series production diesels. In addition, as a result of the overall concept, BMW produces the lightest diesel power unit in its performance segment (40 to 60 kg lighter than a V8 diesel with the same output). The remarkable output of this diesel engine is perfectly complemented by the adequate agility and supreme handling qualities of the BMW automobiles it powers.
Variable Twin Turbo technology: two successively actuated turbochargers.
Variable Twin Turbo technology allocates the compression of intake air to two different-sized turbochargers – a process undertaken in the past by just one single turbocharger. The smaller turbocharger operates at low engine speeds, the larger at higher speeds.
The larger turbocharger is a good example of the extent to which BMW engineers have specialised this technology. The operation of an engine equipped with only this turbocharger would simply be not possible.
Essentially, BMW Variable Twin Turbo system differentiates between three different operating conditions:
At low engine speeds the intake air flows through the large turbocharger and is compressed in the smaller turbocharger. Thanks to its optimum efficiency within this range, it supplies substantial amounts of air to the power unit, starting at idle speed without any appreciable time delay. The 3.0 litre inline six-cylinder diesel develops 530 Nm of torque at as early as 1,500 rpm.
With increasing engine speed the larger turbocharger becomes more important – initially as a pre-compressor. The intake air is additionally highly compressed inside the small turbocharger, the engine reaching its maximum torque of 560 Nm at 2,000 rpm. By means of a turbine control valve the flow of exhaust air is variably distributed to both turbochargers, thereby regulating interaction.
At high engine speeds work is done primarily by the large turbocharger, the power unit reaching a maximum output of 200 kW/272 bhp at 4,400 rpm.
From motor sports into series production: acid test at the Dakar Rally.
From motor sports into series production – this BMW-typical dovetailing with motor sports was also successful in the case of the new high-performance diesel. At the 2003 Dakar Rally, specialists at the Diesel Competence Centre in Steyr (Austria) already used the new technology with two variable turbochargers in an X5 entered by the independent X-Raid team. High power at low engine speeds during cumbersome sand dune stages, top speed on asphalt – under conditions in which, in the eighties, BMW celebrated a series of victories with motorcycles featuring boxer engines, BMW diesel specialists have now tested a revolutionary technology in engine construction.
During its first appearance, the X5 with its revolutionary turbocharging system already managed to seize victory in the diesel category. After successfully completing one of the world’s most demanding motor sport events, Variable Twin Turbo technology had proven its dependability under severe competitive conditions. The diesel specialists were then able to start fine tuning the car and make preparations for large-scale production.
To conclude the final stage of testing, the BMW X5 was once again entered for the Dakar Rally. And this time victory was achieved not only in a sporting sense but also technologically. On 17 January 2004 two BMW X5s, powered by the innovative 3.0 high-performance, near-production diesel, were the first to cross the finishing line in Dakar.
The X-Raid team clinched first place in the diesel category and was able for the first time to win stages of the rally in a diesel-powered vehicle, accomplishing 4th and 8th places in the overall rating. The new BMW sports diesel engine could not have made a more impressive job of underlining its potential.
Diesel engine with a higher specific power than the former M5.
With a specific power output of 66.7 kW, the new 3.0 litre diesel even exceeds the rating achieved by the M5 sports saloon (58.8 kW/ltr), production of which ceased at the end of June 2003. In this respect the new BMW diesel once again proves that it is worthy of the truly elite group of premium engine builders.
The basic construction of the BMW high-performance diesel is modelled on the diesel engine used in vehicles with different outputs, these being, for example, the Sports Activity Vehicles X5 and X3, or the large 7 Series. Based on this, the power unit was further developed in all relevant aspects and adapted to meet fastidious requirements.
Whilst the 2,993 cc capacity remained unchanged, the crankcase construction was reinforced predominantly within the area of the crankshaft bearing.
Second-generation Common Rail serves as an injection system, whereby the flow characteristic of the fuel-injection nozzles was adapted to cope with the new level of output. Thanks to excellent overall efficiency, the 3.0 litre diesel with Variable Twin Turbo even falls below the specific fuel consumption of the basic power unit in certain driving situations. Injection timing and combustion process (compression ratio 16.5:1) were adapted to the new parameters.
Unique. High-revving and spontaneous up to 5,000 rpm.
The new BMW 3.0 litre diesel with Variable Twin Turbo offers the widest useful engine speed range in its class. In addition to the increase in output, the useful engine speed range was widened by + 400 rpm. Nominal output of 200 kW/272 bhp is at 4,000 rpm and maximum engine speed is now 5,000 rpm, which is unusual for a diesel. The new BMW diesel with Variable Twin Turbo technology will undoubtedly appeal first and foremost to the customer with sporting ambitions, as the engine proves to be a particularly high-revving unit demonstrating excellent response.
Robust and lighter: trapezoidal connecting rod.
When viewed from the side, the upper eye of the connecting rod is shaped like a trapeze. This new technology is used on the internal combustion engine to create an additional supporting surface for the gudgeon pin within the lower area of the connecting rod eye for high piston pressures.
At the same time, weight is saved in the upper (narrower) part of the connecting rod eye. Just a few grams on each connecting rod, which, however, make all the difference, considering the high speed at which the connecting rods move up and down inside the engine.
Like all other BMW connecting rods, those installed in the new inline six engine have also undergone the cracking process. This method entails breaking the lower connecting rod eye in two. The two parts are then bolted together again when assembled onto the crankshaft. Due to the uneven surfaces resulting from the cracking process, the link between the two parts of the connecting rod has far greater stability than the even surfaces obtained on conventionally sawn connecting rods.
Lightweight camshafts with a weight advantage of 1.2 kg.
Thanks to lightweight camshafts the new R6D has a weight advantage of 1.2 kg (–25%). The basic component of the new camshaft is a steel tube serving as a support for the cams prefabricated from highly tensile refined steel. The cams are then joined and finally polished down to an accuracy of 1***61549; (1***8725;1000 mm).
High-performance DDE 6 for complex computing.
Engine electronics required to control a turbocharged power unit are significantly more complex. A system comprising two superchargers, turbine control, bypass and wastegate has to be controlled, and not just a turbocharger with variable turbine geometry. The system elements have to be coordinated with each other and with the respective operating condition of the engine. A highly complex task, which could only be solved using state-of-the-art diesel electronics (DDE 6.0). It provides the required computing power and sufficient storage capacity to deal with processes adequately.
Exemplary: particulate diesel filter complying with EU4 standard.
The exhaust system was specifically designed to cope with the high rate of air flow. Pipe diameter and silencer were developed independently and the sound was adapted to the sporty character of this high-performance diesel.
Powerful engines should be exemplary in their emission behaviour. The new BMW diesel fulfils the stringent EU4 emission standard and comes as standard with a particulate filter.
The sportiest series production diesel of all time
Premiere of 535d Saloon and 535d Touring in the autumn.
The new BMW high-performance diesel engine with Variable Twin Turbo will make its debut in the autumn in the 535d Saloon and 535d Touring. This makes the 535d the only sports car with typical diesel fuel consumption. The saloon sprints from 0 to 62 mph in 6.5 seconds and top speed is limited to 250 km/h (155 mph), using only 8.0 litres of diesel fuel over a distance of 100 km in the EU combined cycle (all figures apply to the automatic transmission supplied as standard). Efficient dynamics at its best.
The comparably low weight of the engine is a continuation of the lightweight concept utilized for the 5 Series. The BMW 5 Series had successfully broken through the weight spiral, as it was lighter than its predecessor from the very beginning: All-aluminium suspension, aluminium brake callipers and the front-end design contributed to this considerably. Consequently, the 535d has no trouble presenting itself as a typical BMW – extremely sporty, remarkably agile and easy to handle.
Once again it becomes clear that a high-performance engine alone cannot accomplish the comprehensively conceived dynamics that make BMW automobiles so distinctive and appealing to BMW clientele. It is the well-balanced package comprising above-average power reserves, spontaneous response, supreme comfort and styling, the unparalleled running smoothness of the inline six-cylinder and exemplary fuel consumption that makes the 535d complete.
The environmental behaviour of the new BMW 535d is equally as exemplary, as BMW does not employ the latest technology in its new top-of-the-range diesel simply to achieve development of power, but also in the treatment of exhaust gas. The 535d comes with a maintenance- and additive- free particulate filter, which, of course, complies with the EU4 standard.
When making its debut, the sportiest series production diesel of all time will set the benchmark and demonstrate sheer understatement.
BMW and the diesel engine:
Technological challenge and sporty driving performance
BMW engine competence adds driving pleasure to diesel-powered cars.
Diesel engines are synonymous with exceptional durability, high torque and low fuel consumption. BMW has added an essential virtue to these strong points – driving pleasure.
Based on 50 years of experience in engine construction, BMW presented its first diesel power unit in 1983. With a 2.4 litre engine it was again an inline six that marked the beginning of BMW’s diesel success story. The 524td was the fastest diesel-powered car of its time, having a top speed of 185 km/h (115 bhp).
BMW as the pacemaker of modern diesel technology.
During 1987 BMW reached its first milestone in the development of the diesel engine: BMW was the first manufacturer to feature an electronic control unit for the diesel engine, namely Digital Diesel Electronics (DDE). DDE by BMW marked a breakthrough in the development of the diesel engine. Above all, a new age began in terms of performance and comfort, with BMW diesel engines becoming high-tech power units. Sporty, smooth-running and economical diesel-powered vehicles, now standard at BMW, would be completely inconceivable without electronic engine management.
From motor sports into series production.
It was not long before BMW also began employing the diesel in competitive sport, this becoming the driving force in the further development of materials and technologies. In 1998, a BMW 320d was the first diesel car in its class to win the 24-hour race at the Nürburgring. Thanks to efficient dynamics, it left the rest of the competition far behind. Less refuelling stops due to lower fuel consumption and superior performance characteristics when accelerating out of bends – at comparably low engine speeds and high torque typical for diesels – bestowed victory on the diesel for the very first time. In the case of the 3.0 litre diesel also, BMW has once again made use of motor sport to test new technologies under extreme conditions.
Balance of output and consumption.
Accurate control and balance of all parameters and engine processes by means of electronics also further enhanced a classic diesel virtue – economy. For instance, the current 525d delivers 130 kW/177 bhp, that is a 54 percent increase in output compared with the first comparable 2.4 litre BMW diesel of 1984. Fuel consumption, however, has dropped from 8.4 litres to 6.7 litres of diesel fuel/100 km. Moreover, the 525d meets the significantly more stringent exhaust requirements and comes as standard with a diesel particulate filter.
Top of the league in just a few years:
Diesel in BMW sport coupés, BMW’s first V8 diesel.
High competence in engine construction, optimum utilization of electronics and a superior package comprising performance, comfort and fuel economy put BMW diesel-powered automobiles in pole position ahead of all competition in their segment. Whilst retaining classic diesel virtues, BMW diesel experts have managed in just a few years to develop the diesel engine into an adequate power unit for sports coupés such as the BMW 330Cd for example. It was also a BMW that presented a diesel engine for the first time in a luxury class automobile in 1999. The 740d was the world’s first V8 diesel from a German manufacturer to be positioned in the highest market segment.
Efficient dynamics: the technology of driving pleasure
75 years after the first automobile produced under the Bavarian flag, BMW is once again underlining its claim to technological leadership with three remarkable power units. With the two six-cylinders, BMW is impressively infringing principles of engine construction previously considered unchangeable. These principles stipulated that higher power output meant supercharging or a larger displacement. Larger displacement inevitably means more weight. Larger displacement and more weight inevitably mean higher fuel consumption.
The fact that heavy engines alter not only the vehicle’s centre of gravity, but, as a result, also negatively affect agility and the driving dynamics desired and perceived by the customer, is also of great significance to BMW. Heavy power units not only have a higher fuel consumption, but also cast a cloud over driving pleasure.
In the opinion of BMW, dynamics consist of more than just acceleration and Vmax values. BMW believes that dynamics comprise the overall behaviour of the vehicle, the performance the vehicle provides to the customer as part of the driving experience. Engine response, high-revving, reaction to steering wheel movement and body shell behaviour are just a few parameters of these dynamics. Their significance is demonstrated for example by the two latest BMW innovations in this field. Dynamic Drive (counteracts body roll) and Active Steering (controls steering angle according to the speed of the vehicle) are considered by customers to be a quantum leap for the immediately perceived dynamics of the vehicle.
Similarly, efficiency is to BMW not merely low fuel consumption, but also in this case an optimum balance between input and output. The parameters for full efficiency, irrespective of whether we are referring to a company or to vehicles and engines, are, therefore, also short development periods, “on demand” and “just in time” production, as well as protection of resources.
BMW engineers aspire to provide the customer with a maximum degree of dynamics. These dynamics are efficiently realized for BMW using the latest materials, innovative solutions and trendsetting technologies.
Dynamics are a basic characteristic of BMW automobiles. To the driver they mean high power density and low weight.
Less weight for more driving pleasure.
For this reason dynamics have been a predominant aspect in vehicle and engine development at BMW for many years now. Increased customer expectations with regard to these brand-significant values, but also an increase in the vehicle’s total weight – for example due to extensive active and passive safety measures or standard comfort features such as automatic climate control – mean that the BMW research department is forced to overcome conflicting goals. Dynamics, safety and comfort must be increased simultaneously and emissions lowered, while at the same time observing the preservation of resources during production and utilization of the vehicle.
One main aspect of all these considerations is weight. Lighter vehicles facilitate a considerable increase in driving dynamics and agility, the core virtues of all BMW automobiles. Less weight, however, also means lower fuel consumption and lower emission.
With regard to construction of body and suspension, BMW engineers successfully tackled these conflicting goals years ago by the utilization of innovative concepts. For example, the 5 Series presented in 1996 was the world’s first car to feature an aluminium suspension. Apart from the actual reduction in weight, the unsprung masses are also decreased, by which particularly dynamic motoring is achieved. Meanwhile, 7 Series Saloons, the 6 Series Coupé and Convertible as well as the new 5 Series Saloon and Touring all feature this pleasantly nimble suspension. All of them are considered to be particularly agile vehicles within their respective segments.
BMW is pushing ahead with the technology required for the development and processing of body structures and components made of carbon-fibre-reinforced plastic (CFP) for use in series production. A prime example of the utilization of the innovative lightweight composite material in series production is the CFP roof of the BMW M3 CSL, which features a tissue structure. The CFP roof is produced at the BMW Landshut plant using the world’s first highly-automated manufacturing process for CFP body components. CFP offers a significant weight advantage coupled with excellent crash behaviour and corrosion-resisting qualities.
A significant measure to reduce weight was, inter alia, the weight- reduced aluminium front end used for the first time worldwide on the new BMW 5 Series. With a weight reduction of 35 kg compared with a conventional steel construction, this technology optimizes the vehicle’s weight in a particularly critical area. The result is predominantly an optimum 50:50 distribution of axle load required to achieve above-average dynamics – a further fundamental precondition for the agility only experienced in a BMW automobile.
These were just three examples of BMW innovation in lightweight construction. With these and many other measures, BMW has consistently emphasized its technological lead in limiting and reducing vehicle weight by the employment of new materials.
Lightweight construction: the ecobalance must be right.
Viewing vehicles in their entirety with the help of ecobalance case studies results in conclusive environmentally-friendly lightweight construction concepts.
In the course of intelligent lightweight construction development, experts at the BMW Group’s Recycling and Dismantling Centre (RDZ = Recycling- und Demontagezentrum) are considering vehicle concepts of the future. One focal point of their interest is ecobalance case studies. For example, detailed ecobalance case studies include the examination of the entire life cycle, taking concepts and components into account. The process chain analysis is comprehensive. It deals with the initial stages of vehicle development and the extraction of raw materials and their processing for vehicle production, as well as the use of vehicles by the customer, including service. However, this still does not close the cycle. For this reason the end of the life cycle, vehicle recycling, is included in the survey.
By viewing vehicles in their entirety, lightweight concepts, which at first glance appear to facilitate a marked reduction in fuel consumption through a considerable saving in weight during the vehicle’s lifetime, are not considered particularly feasible from an ecological point of view. This is the case when, for instance, substantially more energy or emissions are produced for the extraction of raw materials and material processing than can be saved during the entire life cycle of the vehicle through lower fuel consumption. The environmentally-friendly exploitation of utilized materials and substances is a further critical assessment criterion.
Logical concepts – intelligent mixing of materials has a future.
Ecobalance case studies are a suitable instrument for the integral assessment of lightweight construction. Hence each material mix chosen within the framework of a BMW Group vehicle project is based on a logical concept:
As there is no such thing as a universal patent remedy, BMW Group will continue in future to give preference to an intelligent mix of metal and non-metal materials.
BMW engine assembly with flexible structure / © GCF
BMW engine production
BMW engine production plant in Steyr
The BMW Motoren GmbH in Steyr, which will be celebrating its 25th anniversary in 2004, is the largest engine plant within the BMW Group’s global production network. It also serves as a competence centre for the development of BMW diesel engine technology.
Preparation for further growth.
The BMW plant in Upper Austria has built more than 7.5 million engines since 1982, thereby adjusting to the increasing number of units produced and the demands arising from the growing complexity of products and processes. Since the founding of the plant, around 2.6 billion Euros have been invested in building and extension work, in new production technologies as well as in research and development.
The stage VII extension is currently upgrading this location, whereby the main focus is not only on the installation of further machines and engine assembly units, but also on diesel engine development, environmental protection and logistics. With this extension the BMW Motoren GmbH is enlarging its factory area by around a third, thereby increasing flexibility of production and capacity.
Competence centre for diesel technologies.
The BMW diesel engine development centre sited at the Steyr plant has established itself as the competence centre for the entire BMW Group. From here, for instance, innovations such as the first fully electronic control system for the diesel engine, the first V8 diesel direct injection system for a car, or the new twin turbo six-cylinder engine with 200 kW/272 bhp were introduced. Moreover, engineers in Steyr developed a particulate filter, with which 5 Series diesels are equipped as standard and which eliminates particles in the exhaust gas without using additives.
Mechanical production technology.
State-of-the-art production technologies are also used to produce the most essential engine components for the new generation of BMW six-cylinder petrol engines.
The weight-optimized crankcases as well as the crankshafts, cylinder heads and connecting rods are delivered as blanks. Each component is then processed on ultra-modern machines. Last year alone approximately eight million engine parts were turned, milled, drilled, ground and honed with utmost precision.
In the case of the new generation of BMW engines, this processing is carried out predominantly in the 120 flexible processing centres. These are ultra-modern facilities where processing of diverse components is effected without manual tool changes and several processing stages can be carried out simultaneously. Finally, surface finishing is effected in successive processes on additional transfer lines. The swarf produced during processing is removed from the materials and completely recycled.
Process safety and quality.
The highly developed processes of mechanical production, incorporating almost 100 percent automation, are programmed, controlled and monitored by trained specialists.
Trouble-free management of millions of parts can only function within a closely linked logistics network. It guarantees the supply of blanks and the punctual availability of components for engine assembly.
To facilitate maximum transparency, the main components are allocated a matrix code. This permits the storing of all production data in a database. For quality control purposes this data can be called up and the status of each individual component followed up.
Dimensional stability and quality of the processed parts is consistently monitored. In addition, random checks are made and the specimens examined in the precision measuring laboratory, where tolerances are meanwhile measured in thousandths of a millimetre (1***61549; = 0.001).
Maximum customer orientation and short lead times require a high level of flexibility. This is the only way the BMW Group can react to varying market demands and at the same time promise the customer a high level of flexibility when making changes.
In Europe, just four days elapse between the receipt of the order from the vehicle manufacturing plants and installation of the engine into a vehicle.
At BMW’s Steyr plant, diesel engines featuring four and six cylinders as well as six-cylinder petrol engines are assembled. With a 60 percent level of automation, modern production techniques and the employees’ craftsmanship complement each other. In 2003, the share of diesels in total production in Steyr was almost 60 percent.
The complexity of the control of processes is clearly demonstrated by the fact that the new six-cylinder diesel engine in the BMW 535d comprises around 400 individual parts and components. Moreover, depending on the type of vehicle, country of destination, transmission and special equipment, assembly results in a myriad of different engine variants.
In the assembly shop, core components such as crankcase, crankshaft, connecting rod, camshaft and cylinder head are assembled into a so-called short block. The cylinder head and parts of the crank drive are pre-assembled on a separate assembly line.
Testing systems integrated into the production line guarantee consistent first-class quality. For example, an engine-specific bar code read at each assembly point eliminates the possibility of incorrect components or tools being used. The engines are then finally fitted with vehicle-specific components according to order.
The engines are not allocated to a customer order until they have been completed with the corresponding components. Assembly is carried out in sequence, i.e. in the order in which the customers’ vehicles pass through the vehicle plant. The BMW Group’s global logistics network then ensures that each engine is allocated to the correct vehicle on the assembly line.
Long-term utilization of resources also has top priority at the BMW plant in Steyr. For this reason, the so-called cold-testing method, a computer-controlled operational test of fully assembled engines, was introduced. This involves the thorough testing of mechanical systems, acoustics, sealing tightness as well as the optimum functioning of the fuel injection system and electronic components, without the need for burning fuel in the engine. This environmentally-friendly method relieves the environment by a saving of 559,000 litres of fuel each year.
Success factor man.
A high level of qualification and the employees’ commitment to their work are crucial factors for the success of the plant. The BMW Motoren GmbH is not only the largest employer in the region, but also the largest apprenticing company. Around 100 young people are currently being trained for careers in commerce and industry.
Thanks to innovative working time models, machine operation times are decoupled from the employee’s personal working hours, resulting in optimum machine utilization as well as increased flexibility and production.
Engine production within a network
With its automobiles and motorcycles the BMW Group is present in around 160 countries all over the world, currently having at its disposal more than 23 production plants on four continents. This production network includes eight vehicle plants for BMW and MINI production. Three engine production plants and four facilities producing, inter alia, components. Furthermore, the England-based subsidiary company Rolls-Royce Motor Cars Ltd. is currently manufacturing the Rolls-Royce Phantom.
Essential building blocks of the engine network.
The three BMW engine plants in Steyr, Munich and Hams Hall are essential constituents of the BMW Group production network. They are supplemented by capacities from the joint venture Tritec Motors, Curitiba, Brazil, for the MINI brand.
Together they produced more than a million engines last year, these being supplied to all vehicle factories worldwide.
The four-cylinder engines featuring VALVETRONIC produced at the Hams Hall engine plant are destined for BMW 3 Series vehicles and, from the autumn, also for the BMW 1 Series.
The BMW engine plant in Munich builds six-cylinder and eight-cylinder petrol engines as well as special engines produced in limited numbers, such as the power unit for the new BMW M5. Engines from Munich are found in almost all BMW model series.
The largest BMW engine plant in Steyr produces all four and six-cylinder diesel engines as well as the current and future generation of six-cylinder petrol engines. Engines from Steyr power the new BMW 1 Series, the BMW 3 Series, the BMW 5 Series, the BMW 6 Series and the BMW 7 Series and can also be found in the BMW X3, the BMW X5 and the BMW Z4.
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