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Small Commercial Vehicle (SCV) is an emerging Commercial Vehicle (CV) segment both in India and throughout the world. Vehicles in this segment have diesel engine of capacity less than 1 l and GVW of less than 3.5 t. Normally for the CV, engines are tested on engine dynamometer for emission test, but SCV are tested on chassis dynamometer as they are classified as N1.1 class vehicles. Hence SCV have to follow same emission regulations as diesel passenger cars. The main challenge is to meet BS-IV NOx and PM emission target together with high torque optimization along with required durability targets. This paper addresses this challenge and reports the work carried out on an Indian SCV with 0.7 l naturally aspirated indirect injection diesel engine.

Technologies for exhaust aftertreatment of diesel engines are driven by emission standards and Selective Catalytic Reduction (SCR) will play a key role in complying with the requirements, particularly for the heavy duty vehicles. Amongst the variety of catalysts for the SCR reaction, the Vanadium-Tungsten-Titanium-Based (VWT) system is preferred over the base metal doped zeolite because of the established advantages of wide temperature window, robust and durable performance and resistance to sulfur exposure. While the basic chemical reactions involved in ammonia-SCR are well known, the challenge lies in identifying the right combination of substrate and wash coat formulation to meet with customer specific requirements. An insight into the relevant materials properties of the substrates as well as the bulk surface properties of the wash coat such as its ammonia storage capacity, V2O5 dispersion and stability are important.

A novel catalytic converter technology for 2 stroke engine application has been successfully developed and tested on select two wheeler vehicles. The catalytic converter uses spherical beads, as catalyst carrier, that is characterised by its very low thermal expansion coefficient and excellent thermal shock resistance. This catalyst carrier is very different from the old fixed bed pelleted catalyst carrier used in the four wheelers in late 1970's and early 1980's, in terms of its: chemical and mineralogical composition microstructure and other physical properties When suitably catalysed and canned, it offers unique advantages over conventional honeycomb catalyst on account of its high conversion efficiency, good durability and easy catalyst replacement/refill capability. The reactor which houses the catalyst bead is so designed that it offers least pressure drop across the converter and negligible power loss at WOT conditions.