BMW EfficientDynamics in Detail

Page 1: Overview
Page 2: World first direct gasoline injection
Page 3: EfficientDynamics in a new dimension
Page 4: The highest standard

Compact performer with exemplary emission standards: EfficientDynamics in a new dimension – Variable Twin Turbo now also in the BMW four-cylinder diesel.

More power, lower weight and a further improvement in emission management – these are the highlights of the new four-cylinder diesel engines with which BMW now sets the standard for EfficientDynamics in this segment of powertrains. Featuring an all-aluminium crankcase, turbocharging technology, third-generation common rail fuel injection, diesel particulate filters placed closed to the engine, and numerous detailed innovations, the new compact power units open up a new dimension of economic and clean motoring.

BMW’s new four-cylinder diesels displace 2.0 litres cubic capacity and come in three power and performance stages: Both the “basic” model developing 105 kW/143 hp maximum output and the 130 kW/177 hp version come with a turbocharger featuring variable turbine geometry for superior power and performance. The most powerful version of the new engine also boasts Variable Twin Turbo technology already lauded in BMW’s six-cylinder diesel models. This technology also referred to as multistage turbocharging gives the 2.0-litre power unit maximum output of 150 kW/204 hp, making this the first all-aluminium diesel engine in the world to develop output of more than 100 hp per litre.

The new diesel concept is integrated within a network of improved components around the engine serving to minimise fuel consumption and emissions and optimise management of the engine’s ancillary units.
On all models driven by a new-generation four-cylinder diesel Brake Energy Regeneration, an Auto Start Stop function and a gearshift point indicator for manual gearbox cars as well as new electrical power steering serve to enhance efficiency to an even higher, unprecedented level.

Development strategy for EfficientDynamics consistently implemented.

Introducing the new four-cylinder diesel engines, BMW is implementing the development strategy for EfficientDynamics consistently also in this drive segment. Compared with the former power units, the new engines are significantly lighter and offer a substantial improvement of both fuel economy and emission management despite their considerable increase in power and performance.

BMW’s new four-cylinder diesel engines are featured in a number of model series, ensuring that trendsetting innovations in technology for the enhancement of efficiency are available to the customer in several car segments with a particularly high volume of sales. Customers opting for diesel power thus benefit for the first time in both the four- and six-cylinder segment from supreme engine technology offering the highest standard of power and performance plus equally superior economy. A further advantage particularly of BMW’s modern diesel engines is the significant reduction of CO2 emissions.

As a result of all these strengths, BMW’s highly appealing new four-cylinder diesels make an important contribution to the overall reduction of fuel consumption and emissions.

The engines in BMW’s new generation of four-cylinder diesels develop their superior power from a capacity of 1,995 cc and come in three power and performance stages. Their distinction lies in the specific modification of the injection components and the turbocharger system. Developing maximum output of 105 kW/143 hp and peak torque of 300 Newton-metres/221 lb-ft, even the “basic” version of the new diesel outperforms its predecessor by 15 kW/20 hp and, respectively, 20 Nm/15 lb-ft.

The most powerful version of the new engine develops maximum output of 150 kW/204 hp, 30 kW/41 hp more than the formerly most powerful four-cylinder diesel from BMW – and at 400 Nm/295 lb-ft, the engine’s peak torque is up by 60 Nm or 44 lb-ft. The middle engine in the four-cylinder diesel range is a 130 kW/177 hp power unit developing maximum torque of 350 Nm or 258 lb-ft.

Another important factor clearly confirming the extra temperament of the engines is the engine speed band approximately 10 per cent broader than before. Hence, the superior pulling force from low engine speeds so typical of a BMW diesel is now combined with even faster and more dynamic revving characteristics.

This impressive enhancement of engine dynamics comes hand-in-hand with an equally impressive optimisation of all-round economy. In practice, this means that fuel consumption by the new BMW 118d in the EU test cycle is down by approximately 16 per cent versus the former model to a mere 4.7 litres/100 kilometres or 60.1 mpg Imp – despite an increase in power by 15 kW to 105 kW/143 hp. The new BMW 120d, in turn, comes with an increase in output by 10 to 130 kW (177 hp) and an improvement in fuel economy of the same magnitude, the engine now making do with just 4.9 litres of diesel fuel/100 kilometres (equal to 57.6 mpg Imp).

Impressively reaching even the most ambitious targets.

In developing the new family of diesel engines, BMW’s engineers sought from the start to enhance both output and torque while at the same time optimising the weight of the engine and reducing fuel consumption significantly versus the former power units. So it is precisely these features that characterise the BMW Group’s development strategy for EfficientDynamics, with the new four cylinder diesels impressively fulfilling all of these requirements.

For reasons of production technology and efficiency, BMW follows the principle to build four- and six-cylinder diesel engines of the same size (displacement) but in different power configurations. So looking at the new generation of four-cylinders, this means that the 2.0-litre has been developed in no less than three different versions.

All-aluminium crankcase for optimum engine weight.

Both the “basic” and the top engine significantly outperform their predecessors in terms of both output and torque. And at the same time the new engines are 17 kg or more than 37 lb lighter than the former generation four-cylinder diesel. This optimisation of weight has a positive impact not only on the car’s all-round economy, but also on the harmonious distribution of axle loads. And this, in turn, means improved agility in the models driven by BMW’s new four-cylinder diesels.

In terms of both economy and emissions, therefore, and in the area of driving dynamics, the new engines stand out clearly as the leaders in their respective segments.

The starting point for developing BMW’s new family of engines was the successful four-cylinder diesel with the same size as the new power units, developing 90 and, respectively 120 kW (122 and, respectively, 163 hp) in its former configuration. To take the extra power of the new engines into account, the diameter on the main bearings on the crankshaft has been increased accordingly. A further point is that in parallel to the increase in power, engine weight has been significantly reduced mostly by the new aluminium crankcase with its thermally bonded grey-cast iron bushes taking the place of the grey-cast iron block used so far.

Efficient combustion for optimum fuel economy.

The cylinder head with its intake ducts is a new design. The intake ducts are positioned at the side and designed as a spiral and tangential manifold.
To reduce emissions to an absolute minimum, the spiral duct serving to fill the cylinder is electronically variable in an infinite process. With their larger diameter, the valves facilitate the gas charge cycle and are now positioned upright, facing vertically into the combustion chambers. This avoids the need for extra cavities on the piston surface, which no longer requires separate valve pockets. The turbulence duct, in turn, gives the fresh air flowing into the engine a swirl motion improving the internal mixture formation process.

While the “basic” engine operates at an injection pressure of 1,600 bar and solenoid valves serve to supply the fuel in appropriate doses, the two more powerful engines inject diesel fuel at a pressure of 1,800 and, respectively, 2,000 bar through four piezo-injectors. The most powerful version of the new diesel is incidentally the first engine ever to use piezo-injectors operating at this high pressure of 2,000 bar.

To make the combustion process even more efficient, both the shape of the combustion chambers and the trough at the bottom of the piston have been modified and the compression ratio reduced to 16 : 1. And since fuel is injected in up to three “doses” for each operating stroke of the engine, the ignition flames spreads in a relatively “gentle” process benefiting in particular the smoothness and refinement of the diesel engine.

Various improvements within the engine itself – reduction of friction, redesigned combustion chambers, optimisation of the mixture formation process, combustion and air guidance – ensure a significant improvement in fuel economy right from the start. This improvement is supplemented by various other technologies and features on the car itself, such as Brake Energy Regeneration, the Auto Start Stop function, the gearshift point indicator, as well as EPS Electrical Power Steering.

Making its debut in the four-cylinder diesel: Variable Twin Turbo technology.

Two-stage turbocharging in the 150 kW/204 hp top version of the new four-cylinder diesel ensures a particularly fast response and even more muscular power. Variable Twin Turbo technology has already been introduced in the world’s most sporting and dynamic six-cylinder diesel featured in the BMW 535d. Today this 3.0-litre straight-six developing maximum output of 210 kW/286 hp is available in several model series. The technology providing this unique, dynamic power and performance is referred to as twin-stage turbocharging, a principle now featured for the first time also in a four cylinder diesel.

The turbocharger unit in the Variable Twin Turbo is made up of one small and one large exhaust gas turbocharger. Benefiting from its lower inertia, the smaller turbocharger becomes active at low engine speeds just above idling. At higher speeds the larger turbocharger then also cuts in, developing extra power in the process.

Thanks to this configuration, the turbocharger effect is built up spontaneously without any time lag, developing noticeable thrust and momentum even when the driver barely presses down the accelerator pedal. A turbine control flap distributes the flow of exhaust gases variably to the two turbochargers.

Specially developed, high-performance engine electronics ensure smooth management in the transition phase between the two turbochargers and optimum interaction of the two units with one another. This sophisticated control concept coordinates the complete system of turbines, the turbine control flap, bypass and wastegate as a function of the engine’s operating conditions.

The most powerful of the three new diesel engines develops its maximum torque of 400 Nm or 295 lb ft at just 2, 000 rpm. Maximum charge pressure in the system is limited in this engine to 3.0 bar.

Developing maximum output of 150 kW/204 hp, this power unit enters a new dimension of EfficientDynamics. Through its power and performance, it indeed sets new standards not only in the segment of four-cylinder diesels, since this is the first all-aluminium diesel in the world to offer output per litre of more than 100 hp.

Available in two power stages: BMW diesel with variable turbine geometry.

The drive units developing 105 and, respectively, 130 kW (143 and 177 hp) each feature one exhaust gas turbocharger with variable turbine geometry. This technology allows optimum development of power tailored perfectly to all load conditions. An electric step motor serves to adjust the turbine blades with supreme accuracy and minimum delay to the respective operating conditions and running requirements.

This ensures a spontaneous response at low engine speeds as well as high power and superior performance under full load. Maximum charge pressure in the 105 kW/130 hp power unit is 2.5 bar, as opposed to 2.55 bar in the 130 kW/177 hp version. Maximum torque, in turn, is maintained consistently between 1,750 and 2,500 rpm or, in the latter case, between 1,750 and 3,000 rpm.

Compact power pack with carefully conceived solutions.

For reasons of the car’s package and efficiency in production, all ancillaries such as the coolant pump, alternator and climate compressor are on the intake side of the engine. This arrangement serves inter alia to provide ade-quate space for the two exhaust gas turbochargers featured on the top engine. And since all ancillary units are driven by one single belt, there is no need for a second belt level, which again helps to enhance the overall standard of efficiency by avoiding frictional losses.

The design and construction concept of BMW’s new four-cylinder diesels also has a positive effect on the safety standard of future vehicles. To improve pedestrian safety, for example, the chain drive has been moved to the same side as the flywheel. The high-pressure pump, in turn, is driven by a chain from the crankshaft – and then serves itself to drive the camshaft by way of a second chain.

To make the new engines even more compact, the two balance shafts running in needle bearings in the opposite direction to the engine are integrated in the crankcase at the side. This particular arrangement takes the special configuration and space available in an all-wheel-drive vehicle into account. The balance shafts run for the first time in needle bearings to significantly reduce the frictional forces generated in the process. For thanks to their compact dimensions, the new four-cylinder diesels with balance shafts may also be combined with BMW’s intelligent xDrive all-wheel-drive system.

The oil/water heat exchanger is also housed in a very compact arrangement, fully integrated in the oil filter casing assembled directly on the crankcase.
The filter casing, in turn, is designed for maximum operating efficiency without requiring any hoses otherwise used to connect the heat exchanger to the water shell around the crankcase.

The overall height of the engine has also been reduced by moving the vacuum pump for boosting brakepower from its usual arrangement on the same side as the flywheel to the oil sump for the engine. The compact starter, finally, is fitted on the same level as the seals beneath the engine.

Exemplary emission control thanks to the diesel particulate filter.

To keep the periphery of the engine as clear-cut and uncluttered as possible, the feed pipe for exhaust gas recirculation (EGR) is integrated in the cylinder head. The EGR valve is positioned on the hot side of the engine, the EGR radiator features a bypass serving to limit the emission of harmful substances while the engine is warming up. A further advantage of this concept is that it ensures smooth and cultured engine refinement at all times.

All versions of this new engine generation come as standard with a diesel particulate filter fitted close to the engine. This ensures optimised emission control and management quite unique in this drive segment.

The diesel engine is a core technology used by the BMW Group in its strategy to reduce CO2 emissions. Accordingly, the BMW Group is acting according to the policy agreed by the European Association of Automobile Manufacturers with the EU Commission to reduce CO2 emissions to 140 grams per kilometre in the European car fleet average by the year 2008 – which equals a reduction by 25 per cent versus the level in 1995.

BMW’s newly developed four-cylinder diesel engines are a further step through which the BMW Group is making a clear-cut and decisive contribution in reaching these targets. Indeed, the new BMW 120d already reduces CO2 emissions to 129, the new BMW 118d to an even more impressive 123 grams per kilometre.

A further point is that BMW already fulfils the commitment made by the German automotive industry to fit all new diesel passenger cars with a particulate filter ex works by the year 2008. The diesel particulate filters used by BMW achieve a separation rate already confirmed by the German Federal Office of the Environment of more than 99 per cent, the concentration of particulates in the exhaust emission of a BMW diesel thus reaching a level similar to the concentration in the ambient air – that is in the environment as a whole.

BMW diesel engines: striking out to success with strong muscle and superior efficiency.

Introducing the new four-cylinder diesels, BMW is continuing the successful development of this drive concept. The combination of dynamics and economy which has already given the diesel engine its growing significance, is now being raised to a new level also with the four-cylinder.

Diesel engines have been a firm highlight within the BMW engine range for more than two decades, the production figures of BMW diesel engines increasing more than tenfold since 1983.

The engines featured in BMW cars offer a particularly attractive and, indeed, convincing combination of dynamics, efficiency and motoring culture. Inter alia, these qualities were also the reason why in the year 2005 no less than 39 per cent of all new BMW cars registered worldwide featured a diesel engine. Depending on the model series and sales market, the share of diesel engines is indeed significantly higher in some cases. As just one example, no less than 88 per cent of all BMW X3s sold in Europe in 2005 were driven by a diesel power unit.

Specifications of BMW’s new four-cylinder diesel engines.

Feature/entity	Unit	4 cylinder diesel engine with aluminum crankcase			For comparison: 6 cylinder diesel engine with aluminum crankcase and Variable Twin Turbo technology
Fuel	[ ]	Diesel	Diesel	Diesel	Diesel
Max output	kW	105	130	150	210
at	rpm	4,000	4,000	4,400	4,400
Max torque	Nm	300	350	400	580
at	rpm	1,750–3,000	1,750–3,000	2,000	1,750
Max engine speed	rpm	5,000	5,000	5,200	5,000
Stroke	mm	90	90	90	90
Bore	mm	84	84	84	84
Displacement	cc	1,995	1,995	1,995	2,993
Distance between cylinders	mm	91	91	91	91
Valve plate diameter, intake	mm	27.2	27.2	27.2	27.4
Valve plate diameter, outlet	mm	24.8	24.8	24.8	25.9
Compression ratio	[ ]	16 : 1	16 : 1	16 : 1	16.5 : 1
Fuel injection	[ ]	Common Rail 2nd generation; electro-magnetic injectors; up to 5 separate injections	Common Rail 3rd generation; piezo-injectors; injectors; up to 5 separate injections	Common Rail 3rd generation; piezo-injectors; injectors; up to 5 separate injections	Common Rail 3rd generation; piezo-injectors; injectors; up to 5 separate injections
Fuel injection pressure	bar	1,600	1,800	2,000	1,600
Maximum charging pressure above atmosphere	bar	1,500	1,500	2,000	1,950
sort of turbo charging	[ ]	Turbo charger with variable turbine geometry	Turbo charger with variable turbine geometry	2 stage charging with 2 turbo chargers in line (Variable Twin Turbo technology)	2 stage charging with 2 turbo chargers in line (Variable Twin Turbo technology)
Average maximum combustion chamber pressure	bar	19	22	25.3	24.5
Maximum combustion chamber pressure	bar	170	180	180	180
Engine weight to BMW standard	Kg	152	152	161	196
Minimum specific fuel consumption	g/kWh	198	198	204	205
Output per litre	kW / L	52.6	65.2	75.2	70.2
Power-to-weight ratio	kg/kW	1.44	1.17	1.07	0.93
Crankcase	[ ]	Aluminium	Aluminium	Aluminium	Aluminium
Camshaft	[ ]	Assembled instead of cast	Assembled instead of cast	Assembled instead of cast	Assembled instead of cast
Valves per cylinder	[ ]	4	4	4	4