The launch of the new generation of the compact German sedan, GOLF 8, has been postponed until next October, a few days after the Frankfurt Motor Show. The Golf 8 has been seen several times, especially during a shoot in Madrid, but this week, the last phase of road tests has been started, revealing no details yet on the engines that will animate this 8th generation, but a 1.5 TSI with cylinder deactivation is expected, a 3 cylinder also of 1.0l, and 1.6 and 2.0l diesel blocks.
The Volkswagen Golf 8 will also receive one of the latest innovations from Volkswagen to reduce nitrogen oxide emissions from exhaust gas, this is the SCR system, called "double dosing", when AdBlue is selectively injected upstream of two SCR catalysts installed as standard. The system is used in the new 150hp Passat 2.0 TDI Evo, which already meets the technical requirements of the future Euro 6d emission standard.
This dual dosing process requires a second SCR catalyst that is located in the underbody of the vehicle. Knowing that the distance to the engine is greater, the exhaust temperature upstream of the second catalyst can be less than 100 ° C. This expands the exhaust aftertreatment window: even at engine exhaust temperatures of + 500 ° C, the system can achieve very high conversion rates. In addition, a blocking catalyst downstream of the SCR system prevents excess ammonia discharge.
The innovative dual dosing mix compensates for a disadvantage of modern diesel engines. In fact, they emit less CO2 than gasoline engines because diesel has a higher energy density and the combustion process is more efficient. Diesel engines are therefore subject to special requirements because the combustion of fuel is done with an excess of air. The main component of air is nitrogen, which reacts with oxygen during combustion to form nitrogen oxide.