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The new V8 Power Unit for the BMW M3 - Oil supply and Intake System

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The new V8 Power Unit for the BMW M3
High-speed engine
Formula1 foundry Engine block
Oil supply and Intake System
Dynamic Performance and Engine Management
Ion Flow Technology and Spark Plugs
Engine Specifications
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Reliable oil supply even under extremely dynamic conditions
The high standard of driving dynamics offered by the BMW M3 obviously   calls for a sophisticated supply of oil to and within the engine. Indeed, the engine oil supply is conceived for longitudinal and lateral acceleration of up to 1.4 g – far more than the forces acting on a passenger’s body when taking off and landing in a jet aircraft. The eight-cylinder is reliably supplied with lubricant in all driving situations by two volume flow-controlled pendulum shift cell pumps consistently providing exactly the right amount of oil required by the engine. This is ensured by a change in eccentricity (off-centre arrangement) of the inner rotor in the pump versus the pump housing as a function of oil pressure in the main oil duct. In consideration of the physical forces and loads encountered in an extremely dynamic driving situation, it is conceivable that when the driver applies the brakes particularly hard, for example, the supply of oil to the oil sump serving as an interim storage reservoir would not be sufficient, particularly as the oil sump is positioned behind the front axle subframe for reasons of space. So if the worst came to the worst, lubrication would be interrupted completely. This is however prevented by the concept of “optimum-dynamic wet sump lubrication”, a system with two oil sumps: a small oil sump in front of the front axle subframe and a large oil sump behind the first one. A separate recirculation pump draws oil from the small oil sump at the front under all conditions and feeds the oil to the larger sump at the rear. The larger sump, in turn, is carefully sealed off in order to avoid any splash losses and the formation of foam.
The new eight-cylinder power unit from BMW M also comes with electronic oil level control determining the level of oil by means of a sensor fitted in the oil sump. The data thus measured is transmitted by a serial databus to the engine management evaluating this data by means of various algorithms. The value thus obtained, corrected by the car’s lateral and longitudinal acceleration, is then presented to the driver in the instrument cluster.

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Eight individual throttle butterflies with electronic management
In motorsport this is standard technology, in “regular” cars it is quite rare – the use of a separate, individual throttle butterfly for each cylinder. But precisely this mechanically very sophisticated system is unsurpassed in giving the engine a spontaneous response and supreme performance. And precisely that is what counts in a BMW M Car. The power unit of the BMW M3 so closely related to motorsport comes with eight individual throttle butterflies, four butterflies on each row of cylinders being driven by one actuator in an electronically controlled process. To provide this precise electronic management, the position of the gas pedal is scanned by a touch-free hall potentiometer 200 times a second and evaluated immediately, the engine management registering any change in the position of the pedal and adjusting the individual throttle butterflies accordingly via the two actuators in an instantaneous, split-second process. As a result, it takes the throttle butterflies only 120 milliseconds to reach their maximum opening point – about as long as a routined driver needs to press down the gas pedal. The result, first, is a sensitive and smooth response of the engine at low engine speeds and, second, an immediate, direct reaction of the car whenever the driver calls up more power from the engine.

Flow-optimised air intake
To give the engine an instantaneous, immediate response, the air volume on the intake side of the throttle butterfly must be reduced to an absolute minimum. The problem in this case, however, is the large intake cross-section and air collector volume required by a high-performance power unit of this calibre. So to meet both of these requirements, the throttle butterflies in the intake manifolds are positioned right in front of the intake valves.
From front to rear, the entire flow of intake air in the new eight-cylinder power unit does not require the usual hot-film air mass flow meter with its obligatory sensors. Instead of determining engine load by means of such elaborate sensors, therefore, which would also create disadvantages in air guidance due to the geometry of the components involved, the V8 power unit of the new BMW M3 uses the engine control unit to perform this function. To do this, the system determines engine load under current driving conditions by taking the position of the throttle butterfly and idle adjuster, the position of the VANOS control unit, engine speed, air temperature and air pressure into account. This, in turn, gives the engineers at BMW M GmbH new freedom in the configuration and optimisation of the engine air intake process. And at the same time this management concept operates with maximum reliability.
The length and diameter of the eight intake funnels also helps to ensure an optimum charge effect in the oscillating tube. Like the single-piece, extra-large air collector, the funnels are made of a light composite material with a 30 per cent share of glass fibre. The air filter cartridge in the air collector, in turn, uses the maximum filter area possible, the air collector being supplied with air by an extra-large intake air silencer with three intake air openings.

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Innovative exhaust system
Though its design and configuration, the exhaust system also serves to optimise the cylinder charge cycle. To give the eight-cylinder power unit optimum power and torque behaviour, the focus is on keeping counter- pressure as low as possible, which is why exhaust gas flows through two chambers into the rear-end silencer. The development engineers have likewise given their full attention to consistent lightweight engineering also in developing the exhaust. To achieve these and other targets, the dimensions of the exhaust manifold, the entire exhaust system, as well as all suspension and fastening elements were calculated by means of the CATIA CAD computer system, the 3D data obtained in the process being used consistently also in production and quality assurance.

High-thrust innovation for ultra-thin pipes
BMW M GmbH’s particular innovative strength in engine construction is also borne out by the production methods used. Indeed, one example dates back all the way to 1992, when BMW M GmbH became the first company to use the inner high-pressure moulding process for the then BMW M3 – and since then this process has been consistently refined. Inner high-pressure moulding serves to shape the seamless stainless-steel exhaust pipes from inside under a pressure of up to 800 bar. The result is pipes with extremely thin walls between 0.65 and 1.0 millimetres (0.0256 and 0.0394´´). Clearly, this helps to optimise both the weight of the exhaust system and the response of the catalytic converters.
At the same time this sophisticated technology allows moulding and shaping processes previously not conceivable, as well as even better geometric tolerances. And since all primary and secondary pipes are made of one single piece despite their complex shape and dimensions, many of the former connectors and welding seams are no longer required. Similarly, there are no folding points or tight bends changing the cross-section of the pipes. Instead, the pipes retain their maximum cross-section at all points, minimising any flow resistance in the process.



 
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