did you Think that the diesel was dead? In a time when diesel has been put in fabric of judgment, and with reason, Audi and BMW have decided to bet with force by him, and not only by the concept of diesel for the tourism of low power and average, but also for their vehicles to high performance, as evidenced by the Audi SQ7 TDI with its new V8 TDI with two turbos and electric compressor, and the BMW 7-Series with its new engine six cylinders in line and four turbos. What option is the most interesting? Let’s compare their technologies and their numbers.
The electric compressor in front of the four turbos
why the maximum innovation of these engines is found in their systems of supercharging? Audi and BMW have responded to the challenge of creating a diesel high-flying, and therefore powerful, but above all with sporting qualities. All in all, and with that, the biggest problem with a diesel is still in not enjoy a margin of revolutions suitable to enjoy each gear. The theme of the sound is overcome, will never be comparable to that of a gasoline engine V6 or V8, but these engines offer a sound that has nothing to do with the diesel four-cylinder we’re used to. Therefore, the innovations of Audi and BMW have focused, above all, in improving the response and the linear development of their diesel more powerful.
To achieve this, Audi has resorted to two turbos, and an electric compressor. The great advantage of the electric compressor is in its ability to compress the air, immediately covers the lag, the lag of the turbo, it always depends on the pressure of the exhaust gases. The solution for Audi, on the other hand, is more complex, since it requires an electrical installation of 48 volts, and an extra battery, to work.
BMW, for its part, has opted for four turbos, who follow a strategy of sequential work in low and high pressure, so that the turbochargers of low inertia, is in charge of providing the immediate response that we wish to tread on the accelerator, and the turbos able to compress a greater volume of air, with a pressure of the exhaust gas higher, covering the rest of the regime of the rev counter.
Eight cylinders in a v-versus six-cylinder in-line
Audi has opted for an engine of a large displacement, a V8 4.0-liter. A big motor, but balanced. To some extent we may have been surprised that they have opted for an eight-cylinder motor. Especially since Audi has been working on engines V6 with this same technology. Without going more far, in 2014 since I had the opportunity to test a prototype, the Audi RS5 TDI Concept had a V6 of 3.0 liters and 385 HP of power, and was endowed with a system of two turbos sequential and an electric compressor very similar to the Audi SQ7 TDI. The big difference is that the one prototype was delivering 385 horsepower, and in this Audi SQ7 has managed to get to 435 HP.
BMW it is also an engine balanced, although in this case we find six in-line cylinders and 3.0 liters of displacement. With this engine, BMW has come to the 400 CV of power, using four turbos. BMW has opted for six-cylinder engines in line, and has done so above all by a question of modularity. BMW offers engine three-cylinder in-line, four-cylinder, in-line six-cylinder in-line, both in diesel as in gasoline engines in the background share many technologies. Even its sports of reference, as the BMW M4, used engines, six-cylinder in-line supercharged.
let’s Talk about power and its maximum torque
The Audi SQ7 TDI with its V8 4.0-liter wins the battle of power, delivering 435 HP between 3.700 and 5,000 rpm. The BMW, in any case, is not far behind, delivering 400 HP at 4400 rpm.
In terms of its maximum torque, the Audi once again wins the battle. Audi has managed to reach 900 Nm and do so to a regime surprisingly low, between 1,000 and 3.250 rpm, thanks to the instant response of the electric compressor. The BMW delivery 450 Nm to 1,000 rpm, which is also a figure of great, and reaches its maximum of 760 Nm between 2,000 and 3,000 rpm.
In terms of consumption, the comparison is very difficult. To start, because the vehicles that make their debut these engines are very different, as different as a huge SUV, the Audi SQ7 TDI, and a luxury sedan and representation, the BMW 7-Series. The theory invites us to think that the engine of the BMW will offer a few lower intakes than those of its compatriot Audi. The BMW Series 750d will consume, in the combined cycle is approved, between 5.7 and 5.9 litres/100 kilometres. While the Audi SQ7 TDI already goes up to 7.4 litres/100 kilometres. In any case, and by our experience, I would say that these figures are in reality sure they will be very different.
I don’t know about you, but in motor we are already looking forward to tasting these two new engines to check which solution is the most appropriate for a luxury car that wants to show off of diesel, and high performance.