Audi SQ7 TDI: an impressive technology showcase for a high performance full size SUV.

Audi made the peculiar choice to unveil its new flagship SUV after the press days of the 2016 Geneva Autoshow. The SQ7 TDI marks the return of Audi to full size SUVs delivering massive torque. Instead of the 6 cylinder petrol or diesel engines proposed on the Q7, the SQ7 receives a brand new 3956 cm3 TDI V8 boasting very impressive figures: 435 hp from 3750 to 5000 rpm and a peak torque of 900 Nm available from 1,000 to 3,250 rpm. No typo here: nine hundred newtometers at one thousand rpm. This results in the following performance claims: 0-100 km/h in 4.8 seconds, a top speed of 250 km/h, 7.4 L/100km in the mixed NEDC cycle and 194 g/km of CO2 emissions.

Audi reaches this output with a very sophisticated and innovative forced induction system. Nested between the cylinder banks (“hot V” configuration), the two turbochargers work sequentially through the rev range. They are assisted by a technology first in series production: an electric compressor (EPC for Electric Powered Compressor) brings boost from very low revs. The EPC is powered by a new 48 Volts electric subsystem. Since it does not need to be driven by the crank (supercharger) or by the flow of exhaust gases (turbocharger), the EPC can be summoned at anytime, with a very short 250 milliseconds response time and a maximum of 70’000 rpm. Audi promises therefore an imperceptible lag time and instant throttle response. This technology is the first production instance of the system we test drove in the RS5 TDI Concept.

At full load, EPC draws 7 kW of power, hence the necessity of a higher voltage electrical system to keep current at manageable levels. The 48V system is powered by a Lithium Ion buffer battery of 470 Wh of charge and 13 kW of peak power. A DC-DC converter recharges the battery from the 12V main power system used in the rest of the SQ7, as in any other conventional car.

Another innovation on the this 4.0 TDI V6 is the Audi Valve System (AVS). Every cam on the camshaft features to profiles, both on the induction and exhaust side. On the induction side, one cam is obtimized to operate in conjunection with the Electric Powered Compressor, the other to operate at maximum power. On the exhaust side, the second cam governs the actuation of the second turbocharger through dedicated exhaust ports. Exhaust flow is thereby separated between each of the two exhaust valves, directing exhaust flow with either of the two turbochargers.

The chassis receives also new enhancements. The Driving Dynamics Package includes not only a sports differential, real wheel steering and a pneumatic suspension, but also a new active antiroll system called eAWS. On uneven terrain, the anti-roll bars are disconnected, thereby allowing free movement of each of an axle’s wheels. In sporty driving, an electric moteur can not only link the two halves of the antiroll bar, but twist them to counter body roll. Both front and rear axles act independently. The eAWS is also powered by the 48V electric system.