Page 1: Short story
Page 2: New achievements - Hello V8
Page 3: Advanced construction
Page 4: Auxiliary systems
Auxiliary systems
Exceptionally clean and audibly dynamic
Generally, only racing engines feature a fan-type exhaust manifold leading out of the cylinders. But it almost goes without saying that the new V8 also boasts this technology, the two 4-in-1 fan manifolds made of stainless-steel optimised for consistent length and diameter in elaborate computer processes capitalising on the gas-dynamic configuration of the entire system.
The two catalytic converters – one in each exhaust pipe – are positioned close to the engine. These primary catalysts quickly reach their optimum operating temperature since the thin walls of the exhaust manifolds minimise any thermal inertia of the material while warming up, thus ensuring a very fast response after starting cold. Two particular features of the catalytic converters are their low pressure loss and the high standard of mechanical strength.
Two additional tri-metal-coated catalytic converters then come further down-stream, integrated in the underfloor of the car. Interacting with one another, the four catalysts clean the exhaust gases very effectively. Hence, BMW M’s new V8 power unit fulfils all the requirements of the European EU4 standard and the US LEV 2 classification.
Noise emissions are likewise exceptionally low. Apart from the two interim silencers, particularly the single-piece rear muffler in crosswise arrangement with its very large volume of 35 litres serves to reduce the noise level. The new V8 power unit nevertheless boasts an exceptional sound and audibly sporting character once again typical of BMW M and at the same time offering a unique touch of racing performance for all senses.
Brake Energy Regeneration for greater efficiency and dynamic performance
Brake Energy Regeneration also serves on the new V8 power unit in the BMW M3 to enhance all-round drivetrain efficiency to an even higher level, concentrating the generation of electrical energy for the car’s on-board network on the engine’s overrun mode and application of the brakes.
This highly efficient energy management related to actual driving conditions is made possible by intelligent control of the alternator. The two advantages offered by Brake Energy Regeneration in practice are that, first, specific, on-demand generation of electrical energy serves to reduce fuel consumption, while, second, the driver benefits directly from the disconnection of the alternator when the engine is running under load: With the generation of electric power being cut off when running under load, more drive power is available to accelerate the car, meaning not only greater all-round economy, but also extra driving pleasure.
With the number of charge cycles increasing as a result of such intelligent power generation, BMW combines this Brake Energy Regeneration tech-nology with modern AGM (absorbant glass mat) batteries able to withstand a much greater load than conventional lead acid batteries. In an AGM battery, the acid is held in micro-glass-fibre mats between the individual layers of lead, the battery thus remaining able to store energy over a long period even when charged and discharged regularly.
Even greater performance: the new engine management system
The MSS60 engine management system is the central “brainâ€Â' responsible for the car’s excellent performance and emission data. The system is an evolutionary development of the engine control unit already featured in BMW M GmbH’s V10 drivetrain, raising the standard of control functions to an even higher level: While the control unit on the V10 engine, featuring more than 1,000 individual components, already offers a level of package density quite unparalleled by the competition, the number of components in the MSS60 control units is even higher.
Benefiting from this highly sophisticated concept, MSS60 coordinates all functions of the engine with the various other control units on the car. The three 32-bit processors are in a position to handle more than 200 million individual operations a second, taking, for example, more than 50 incoming signals to calculate the optimum ignition timing individually for each cylinder and operating cycle, the ideal cylinder charge, the injection volume and injection timing. At the same time, the MSS60 control unit calculates and sets the optimum camshaft angle, just as it sets the positions of the eight individual throttle butterflies.
Electronic throttle butterfly control measures loads and forces for optimum management, measuring the driver’s commands by means of the potentio-meter on the gas pedal and converting this signal into the appropriate response. The Drive Power Manager then adjusts this signal by adding additional input from ancillary units such as the climate compressor or the alternator. Signals from the idle speed control, exhaust management and knock control are also coordinated and compared with the maximum and minimum force signals obtained from DSC Dynamic Stability Control and EDFC Engine Drag Force Control. The final signal obtained in this way is then sent to throttle butterfly management, taking the current ignition angle into account.
Engine management with a wide range of additional functions
The MSS60 control unit is more than “justâ€Â' a conventional engine manage-ment system in the direct sense of the word. With its hardware, software and functions having been developed completely by BMW M GmbH, MSS60 is able to support numerous M-specific functions on the clutch, transmission, steering and brakes.
Precisely this is why the driver of the new BMW M3 is also able, simply by pressing the Power Button on the selector lever cover, to activate an even more sporting and dynamic driving program. This provides an even more progressive control map for accelerator travel acting on the throttle butterfly opening, with the dynamic transition functions on electronic engine management showing an even more direct, spontaneous response.
As soon as the driver starts the engine, the control system automatically switches to the more comfortable of the two programs. The driver never-theless has the option to preconfigure and activate the change in programs in the MDrive control unit, which also offers another, extra-sporting and dynamic program.
Last but certainly not least, engine management also performs a wide range of on-board diagnostic functions using various diagnostic routines for servicing at the workshop, just as it offers other sophisticated functions and masterminds various peripheral units around the engine.
The highlight in engine management: ion flow technology
One of the highlights of the engine control unit is ion flow technology serving to determine the risk of the engine knocking as well as misfiring and miscombustion. This significant innovation from BMW was introduced as a standard feature for the first time on the V10 power unit in the BMW M5. Now, in its latest configuration, ion flow technology no longer requires an ion flow satellite, whose function has been integrated in the ignition coil.
“Knockingâ€Â' is undesired selfignition of fuel in the cylinder. Engines without knock control have a lower compression ratio and their ignition point comes later (retarded ignition), since the engine would suffer from going beyond the knock limit. However, this “safety marginâ€Â' costs fuel, engine power, and torque.
By contrast, active knock control allows the engine to run with optimum ignition timing and protects the engine from damage. It also offers the highest standard of efficiency.
With conventional anti-knock control sensors measuring body sound are fitted outside on the cylinder. But the ability of such sensors to detect knocking in the combustion process decreases with increasing engine speed and a growing number of cylinders – and particularly such accuracy and reliability is essential on a fast-revving eight-cylinder in order to optimise combustion quality in the cylinders and, as a result, the service life of the battery and the exhaust emissions. Hence, ion flow technology measures the risk of knocking exactly directly where this phenomenon occurs – within the combustion chamber.
In this process the system uses a physical phenomenon resulting from the high temperatures of up to 2,500 oC encountered in the combustion chamber during the combustion process. These high temperatures and the chemical reactions occurring during combustion serve to partially ionise the fuel/air mixture inside the combustion chamber, this gas becoming electrically conductive particularly along the flame front due to the generation of ions resulting from the separation and deposition of electrons (ionisation). The so-called ion flow generated in this way is measured between the electrodes by an electronic measurement unit electrically isolated from the cylinder head and interacting with engine management. This unit is inte-grated in the ignition coil and interacts with the spark plug electrode to which a specific direct current is applied to generate the signal required. This signal, in turn, depends on the degree of gas ionisation between the electrodes.
Measurement of ion flow thus provides information on the combustion pro-cess directly where combustion takes place. The electronic “brainâ€Â' integrated in each ignition coil receives the signal from the spark plugs on all of the eight cylinders, reinforces the signal and conveys this data to the engine management unit. Analysing this incoming data, engine management then controls the cylinders as required, for example by adjusting the point of ignition ideally to the combustion process for the purpose of efficient knock management.
Using an innovative semi-conductor circuit to measure the control voltage required and reinforcing/multiplying the incoming signals in a variable process, the engineers at BMW M have raised ion flow technology to an even higher level in an important new step. And now this circuit control is integrated directly in the ignition coil together with the terminal stage of the ignition for the first time in the new BMW M3, detecting the ion flow signal even more directly within the combustion chamber, then reinforcing the signal and breaking it down into individual elements for even finer measurement.
Spark plugs taking on additional control functions
This technology thus uses the spark plug in each cylinder to sense and, if necessary, control the risk of knocking. At the same time it supervises the ignition and recognises any misfiring. In other words, the spark plug serves as a calculator for the ignition and as a sensor monitoring the entire combustion process, distinguishing between misfiring and mis-combustion. And precisely this dual function performed by the spark plug facilitates diagnostic processes in the maintenance and service of the car.
Specifications
| Feature/entity | 2nd engine of the M engine family |
| Fuel | Otto RON 98 (95) |
| Max output | hp (kW) 420 (309) |
| at | 8,300 min–1 |
| Max torque | 400 Nm |
| at | 3,900 min–1 |
| Max engine speed | 8,400 min–1 |
| Stroke | 75.2 mm |
| Bore | 92.0 mm |
| Displacement | 3,999 cm3 |
| Distance between cylinders | 98 mm |
| Cylinder arrangement | 8-cylinder V-engine |
| Valve plate diameter, intake | 35.0 mm |
| Valve plate diameter, outlet | 30.5 mm |
| Compression ratio | 12.0 |
| Fuel injection | Intake pipe fuel injection |
| Fuel injection pressure | 3–6 bar |
| Average combustion chamber pressure | 12.6 bar |
| Maximum combustion chamber pressure | 100 bar |
| Engine weight to BMW standard | 202 kg |
| Output per litre | 105 hp/L |
| Power-to-weight ratio | 0.65 kg/kW |
| Crankcase | Aluminium |
| Valvetrain | Infinite camshaft adjustment and hydraulic valve clearance adjustment for intake and outlet (double VANOS) |
1 | 2 | 3 | 4
Related entries:
BMW EfficientDynamics in Detail
New BMW M3 Officially Revealed
BMW M3 Coupe
Source URL: http://nensycarblog.blogspot.com/2008/01/new-bmw-m3-v8-engine-in-detail_7082.html
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