The history of BMW's modern turbo engines going back to the year 2006 is characterised by spectacular power and exemplary efficiency. And now BMW is opening up a new chapter in this history, the straight-six gasoline engine powering the BMW 535i Gran Turismo consistently continuing the process of optimising engine power while at the same time reducing both fuel consumption and CO2 emissions on an engine of this calibre.
The 3.0-litre power unit, for example, is yet a further result of the BMW EfficientDynamics development strategy, offering a range of highlights in technology never seen before on any other engine - highlights created in the context of BMW EfficientDynamics and now ideally matched for optimum driving dynamics and economy all in one.
The new straight-six is the world's first engine to combine turbocharging, direct gasoline injection and fully variable VALVETRONIC valve management developed by BMW. The turbocharging process follows the twin-scroll principle already applied successfully by the BMW Group and now further enhanced consistently for use in a particularly powerful and sporting straight-six.
The combination of this turbocharger technology with High Precision Injection and VALVETRONIC exclusive to BMW exceeds even the response and efficiency of the BMW Twin Turbo power unit launched back in 2006.
Response even better than before, fuel consumption even lower.
VALVETRONIC has already proven its qualities in numerous BMW engines the world over as a particularly effective technology providing even greater efficiency. The big advantage of VALVETRONIC is the infinite control and adjustment of valve stroke on the intake valves, making the throttle butterfly used in former times superfluous. VALVETRONIC reduces throttle losses in the charge cycle process to an absolute minimum and optimises engine response since the air mass required to control the combustion process is masterminded in the engine itself and not outside the power unit with the usual "dead" volume. This ensures particularly efficient use of the energy contained in the fuel, developing a very muscular torque curve and giving the engine optimum response.
In particular, the better response of a VALVETRONIC engine results from the fact that underpressure under part load is only approximately 50 millibar, while on a conventional engine up to 800 millibar of underpressure has to be set off.
On the BMW 535i Gran Turismo the VALVETRONIC functions have been optimised again by a new adjuster complete with a fully integrated sensor serving above all to make the adjustment process even faster than before. Indeed, the inertia factor on the new adjuster is only one-tenth the figure on the former model, serving to further improve engine response.
Responding smoothly, directly and immediately to the gas pedal, the new straight-six is clearly the leader in its class also in this discipline. Maximum torque of 400 Newton-metres/295 lb-ft, for example, comes at just 1,200 rpm.
Apart from the optimised VALVETRONIC control unit, the newly developed turbocharger also contributes to this superiority, ensuring a particularly spontaneous build-up of power since the ducts of three cylinders at a time are separated from one another both in the exhaust manifold and the turbocharger.
In practice, this means particularly low exhaust gas counter-pressure at low engine speeds, the double ducts then enabling the flow of gas to build up greater dynamism in the exhaust manifold and powerfully drive the turbocharger blades even at low engine speeds. Twin-scroll technology thus combines the benefits of two turbochargers within one system. And now this principle adapted to the BMW straight-six with its high standard of technology marks the ongoing, consistent development of BMW's turbocharged engines.
High Precision Injection with new injector nozzles.
The VALVETRONIC system is fully integrated in the cylinder head. This intelligent and extremely compact arrangement allows a direct combination with High Precision Injection with its injection nozzles placed in the middle between the valves and, therefore, in the immediate vicinity of the spark plug in the cylinder head.
High Precision Injection in the new six-cylinder delivers fuel through innovative multi-hole valves at an injection pressure increased once again in large areas all the way to 200 bar. This ensures extremely precise dosage of the fuel injected as well as a particularly clean combustion process. And last but not least in this context, the direct injection of fuel serves to cool the fuel/air mixture and increase the compression ratio to a higher level than in a turbocharged engine with manifold injection - an advantage contributing once again to the greater power of the straight-six.
Displacing 2,979 cc, the new power unit delivers maximum output of 225 kW/306 hp. It therefore offers all the torque and muscle of a significantly larger eight-cylinder, but comes with much lower weight and significantly lower fuel consumption and emissions. It is indeed far lighter than a comparably powerful eight-cylinder and remains even 4 kilos lighter than the straight-six turbocharged engine already well-established in the market.
The BMW 535i Gran Turismo accelerates from a standstill to 100 km/h in 6.3 seconds and reaches an electronically limited top speed of 250 km/h or 155 mph. The unusually good balance of performance and fuel consumption is clearly expressed by average fuel consumption in the combined EU cycle of just 8.9 litres/100 kilometres, equal to 31.7 mpg imp. And the CO2 rating of the BMW 535i Gran Turismo is just 209 grams per kilometre.
The BMW 535i Gran Turismo, like the other two model variants, comes as standard with a wide range of BMW EfficientDynamics technology. Supplementing the excellent efficiency of the respective engine and the eight-speed automatic transmission, features such as Brake Energy Regeneration, on-demand management and operation of ancillary units including the electrical coolant pump, the electrical power assistance pump and the detachable a/c compressor, as well as consistent lightweight engineering, optimised aerodynamics including active management of air flaps, and tyres with reduced roll resistance, ensure optimum fuel economy and emission management at all times.
The power unit of the BMW 535i Gran Turismo is the first turbocharged engine to feature a map-controlled oil pump which, taking up less energy, makes a further contribution to motoring efficiency. Yet a further point is that the new straight-six power unit with turbocharger, High Precision Injection and VALVETRONIC, does not require sulphur-free fuel and may therefore be used without problems the world over. The final point is that the engine naturally fulfils both the EU5 emission standard in Europe and the ULEV II standard in the USA.
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