Even while mired in the mess that is Dieselgate, Audi (and parent company Volkswagen Group) have chosen to continue pursuing Turbocharged Direct Injection technology, making it more powerful, more responsive and hopefully cleaner. That’s all very apparent in Audi’s new SQ7 TDI: a diesel-powered V8 performance SUV with new clean-air tech and, more importantly, some seriously advanced turbos.
In a normal turbo engine, exhaust gas powers the turbocharger, which needs to spin very fast to give the motor its boost in power. But it takes time for the exhaust gas to spool up the turbos, causing “turbo lag” and slower acceleration. To combat this in the SQ7, Audi developed a 48-volt lithium ion battery-powered electric compressor and placed it downstream from the intercooler. The compressor can be activated in 250 milliseconds get the turbos spinning sooner than they normally would, giving the SQ7 more responsive power delivery — with no lag. The turbos in the SQ7 are also arranged sequentially, so the first turbo kicks in at low and intermediate rpms while the second one kicks in higher in the rev range, making for smooth, linear power delivery. This is a big deal if you’ve ever experienced the frustration of turbo lag.
The 4.0-liter V8 itself produces 429 horsepower and a monstrous 663 lb-ft of torque and sends it to all four wheels via an eight-speed Tiptronic transmission. With that lag-free engine and all that torque Audi says the SQ7 will hit 0-60 in 4.8 seconds while still achieving an average fuel economy of 31.8 mpg. For obvious reasons, Audi has made clear that the new diesel system should be clean, too. It uses an NOx oxidating catalytic converter with a secondary Selective Catalytic Reduction (SCR) Converter and AdBlue urea injection to reduce nitrogen oxides. (It’s worth noting that most of the Dieselgate cars did not utilize SCR and urea injection, and this new setup should be cleaner than the scandal-plagued motors of yore.)
According to Audi USA spokesman Mark Dahncke, “the SQ7 is not officially signed off on for the US, but we are optimistic.” So while it isn’t a done deal, there is a strong possibility we will be seeing the SQ7 come to US shores at some point. And that’s a good thing. If Audi can deliver diesel engines that actually function as advertised, we could see a new wave of better — and faster — diesel cars here in the US.