Tuesday 27 September 2016

Audi diesel powers Bentley's Bentayga SUV

Bentley Motors has announces plans to install a diesel engine in its Bentayga luxury sports utility vehicle (SUV).
Bentley Motors claims that “at the heart of the world's fastest and most powerful luxury diesel SUV is an all-new, technologically advanced, triple-charged, 4.0-litre, 32-valve V8 engine.
But is the 4-litre V8 diesel based on Audi’s 4-litre TDI V8 diesel? That is the question.
In fact it is only true as, according to Bentley the new diesel was "co-developed" with Audi. And it should be remembered that Audi and Bentley are part of Volkswagen AG.
Developing 435 PS (429 bhp) and 900 Nm (664 lbft) of torque, Bentley claims the  Bentayga Diesel can hit a top speed of 270 km/h (168 mile/h) and can accelerate from 0-100 km/h in 4.8 s (0-60 mile/h in 4.6 seconds).
Bentley says that its Crewe-based engineers have “developed a V8 powertrain to deliver an authentic Bentley driving experience”.
Peak torque is available from “very early in the rev range (just 1,000 rev/min), which makes progress in the Bentayga Diesel truly effortless.”
However, Bentley Motors is less forthcoming when asked for details of the engine. Despite requests the three different communications people in the organisation, the company failed to communicate with this newsletter.
However, since posting this blog Bentley has responed and the new V8 diesel has an alumium cylinder block.
Bentley does say that “new clean technology gives the Bentayga Diesel the lowest CO2 emissions of any Bentley, as well as a range of over 1,000 km (621 miles) – allowing owners to, for example, drive from London to Verbier, Bordeaux or the Scottish Highlands on a single tank.”
And Wolfgang Dürheimer, chairman and chief executive of Bentley Motors, has proclaimed: “The Bentayga Diesel represents a moment of immense significance in Bentley’s history, by giving the world its fastest luxury diesel SUV. Immense power, grand touring capabilities and superb refinement – this is a true Bentley. Only Bentley could produce a car so powerful, yet so refined.”
                                      Clean, Powerful Performance
And the company adds that the Bentayga Diesel, which will be inproduction in early 2017, “retains the dynamic performance of the Bentayga W12, while introducing clean technologies and enhanced range.”
It adds again that the “next-generation 4-litre V8 engine, mated to a ZF eight-speed automatic transmission, develops a class-leading 435 PS (429 bhp) and 900 Nm (664 lb. ft.) of torque. Variable-geometry, sequential twin-scroll turbochargers are powered by the exhaust gases, while a third electric supercharger – powered by Bentley’s innovative 48V system – spools up within 30 microseconds to eliminate turbo lag. The effect is effortless, seamless power delivery across the entire engine-speed range – the quintessential Bentley driving experience.”
The company further suggests that “an immense amount of torque is available from very low speeds, with peak torque achieved from just 1,000 rev/min, for both seamless on-road performance and exemplary off-roading ability. The immediate flow of power complements the traditional, class-leading refinement and performance customers have come to expect.”
                                 TDI Co-developed with Audi
But the question remains: Whose engine is it? Is it based on the Audi 4-litre turbocharged V8 engine which has a compacted graphite iron (CGI) vee cylinder block sourced from Bruhl in Germany? 
According to Bentley its new V8 diesel has an aluminium vee block and the engine itself was "co-developed" with Audi and "as such is built at a facility in Europe". And the vee block does not use either steel or iron liners, but instead has APC-coated bores.
Earlier this year, Audi declared regarding its SQ7 TDI model:
“The all-new 4.0 TDI generates its power from a displacement of 3,956 cc, combining superior performance with low consumption. With 320 kW (435 bhp) and 900 Nm (663.8 lbft) of torque between 1,000 and 3,250 rpm, the SUV sets new benchmarks in the segment. The V8 diesel engine accelerates the Audi SQ7 TDI from 0 to 100 km/h (62.1 mph) in 4.8 seconds, and on up to an electronically governed top speed of 250 km/h (155.3 mile/h). In the NEDC, however, it consumes just 7.2 litres per 100 Km (32.7 US mile/gal), corresponding to 189 grams CO2per kilometer (304.2 g/mi).
The new 4.0 TDI is a biturbo that is supported in the lower range by an electric powered compressor (EPC). Its two exhaust-gas turbochargers feature a variable turbine geometry and produce up to 2.4 bars of boost pressure (relative). The EPC supports the turbochargers whenever the exhaust gas provides too little energy for the rapid development of power.
The electric powered compressor is placed in a bypass downstream of the intercooler, i.e. close to the engine. Instead of a turbine wheel, it houses a compact electric motor. It accelerates the engine’s compressor wheel up to 70,000 rev/min in less than 250 milliseconds. With the support of the electric powered compressor, the power of the 4.0 TDI is always available spontaneously and without delay when the accelerator is depressed.” 
Whatever the truth, Bentley talks about “a number of specific developments to provide peerless refinement. For example, the bespoke exhaust system has been acoustically engineered to be as quiet and refined as possible.
Bentley does however add that the “addition of Selective Catalytic Reduction (SCR) contributes to lower nitrous oxides. Combined with Bentley’s stop-start system; class-leading CO2 emissions of 210 g/km; and an impressive range of over 1,000 km between fuel stops, this technology puts the Bentayga Diesel at the forefront of advanced engine efficiency.”
But maybe Bentley owners are not too bothered who develops and manufactures the engine under the bonnet, only that the powertrain gives “peerless performance”.
Customer deliveries will begin in Europe early next year, with entry into Russia, South Africa, Australia, New Zealand and Taiwan planned across the rest of 2017.
The Porsche Panamera 4S Diesel is powered by a twin-turbocharged 4-litre engine with a variable geometry turbine. The engine has an output of 422 bhp (310 kW) and a peak torque of 850 Nm between 1,000 and 3,250 rev/min. Acceleration to 60 mile/h is 4.5s and maximum speed is given as 177 mile/h. Porsche, like Bentley is part of Volkswagen AG.

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