Audi released details of the long-awaited release of its TDI clean diesel engines in the U.S. and Canada. Next winter, in January 2009, 50-state compliant versions of the 3.0-liter TDI V6 engine will make the first stateside appearance in the successful Audi Q7 crossover SUV.
Technological improvements employed by Audi to meet CARB’s low-emissions-vehicle (LEV) tailpipe standards — equivalent to federal tier 2, bin 5 — include cylinder pressure sensors, NOx sensors, revisions to the variable-geometry turbocharger and exhaust gas recirculation (EGR) system, a urea injection system called AdBlue and a second exhaust catalyst.
The AdBlue system sprays small amounts of a urea solution just upstream of the new DeNOx catalyst, where it reacts in the heated environment to reduce NOx emissions. AdBlue is stored in a 6.2-gallon tank — enough to last to the next scheduled oil change.
Source: Inside Line