IAA Hannover 2012: Scania unveils Euro-6 SCR-only engine range

Scania sprang a surprise at the IAA Hannover show by unveiling Euro-6 engines solely reliant on SCR exhaust after-treatment.

Scania’s first Euro-6 engines, the 440hp and 489hp 12.7-litre DC13 unveiled last year, comply with the tough Euro-6 NOx limit by using a combination of in-engine EGR, followed by a second stage of SCR exhaust after-treatment.

Other truck manufacturers are following the same broad EGR plus SCR strategy, with only Iveco bucking the trend by rejecting EGR entirely in favour of removing all the NOx by SCR in the exhaust.

Now Scania said it too sees a future for SCR-only engines and will offer its 9.3-litre, five-cylinder DC09 Euro-6 engine in either EGR+SCR or SCR-only versions.

Engines with nominal ratings of 250hp and 280hp will use both EGR and SCR, while the 320hp and 360hp ratings will only have SCR. All ratings also use the Scania/Cummins XPI common-rail fuel-injection, variable geometry turbocharging, a diesel oxidation catalyst and a diesel particulate filter.

The advantages of going for the SCR-only strategy include eliminating the EGR system and cooler and the fact that intake air is cleaner without EGR, so oil stays cleaner for longer.

The downside of the SCR-only approach is higher Ad-Blue consumption, likely to be about 8% of the fuel consumption at Euro-6, compared with 4%-5% at Euro-5.

Euro-6 versions of the 9.3-litre, five-cylinder, spark-ignited gas engine were also at Hannover. These are very different from their Euro-5 counterparts, using stoichiometric combustion and multi-point gas injection rather than the previous lean-burn and single-point injection. Nominal ratings have risen, to 280hp and 340hp, and their torque ratings (1,350Nm and 1,600Nm respectively) are now much better, closer to diesel equivalents.