Cummins looks set to outshine its rivals in the North American heavy-truck market in the crucial matter of fuel consumption, for the next year or two anyway. The company is uniquely placed to exploit a fortuitous combination of unrelated factors: the EPA’s emission credit system and the use of urea-fed SCR technology for NOx control.
As fuel costs continue to rise, Cummins will be using its consumption advantage to stave off the threat to its market share posed by the European-style vertical integration which is gradually taking hold of North American heavy truck manufacturing, at least as far as engine sourcing is concerned.
Daimler’s Freightliner and Western Star brands have, for a decade or more, promoted the group’s in-house Detroit Diesel engines. Volvo, including its Mack brand, continues to push its customers towards its own Swedish-designed power units. Navistar is now in production with its MAN-derived MaxxForce 11 and 13 units, while Paccar’s use of the 12.9-litre DAF engine from its Dutch subsidiary in class 8 Kenworth and Peterbilt chassis is now imminent.
With its late-in-the-day decision to add SCR to its existing EGR installation for NOx control, Cummins could almost certainly meet the 0.2g/hp-hr limit required for full EPA 2010 compliance
Those moves towards powertrain self-sufficiency are, by definition, a threat to any independent heavy-duty diesel supplier, of which there have, in recent years, been only two contenders, both long established – namely Caterpillar and Cummins. Cat has already thrown in the towel, having acknowledged that its production volumes of on-highway US and Canadian market engines would become so diminished, by in-house engine substitution, that it could not justify the R&D and manufacturing costs of meeting EPA 2010 emission requirements.
That has left Cummins to fight what might be seen as a bizarre battle against its own class 8 OEM customers. Its success in the US and Canada has, till now, relied on the long-standing loyalty of end-users, reinforced by a ‘pull through’ marketing strategy, aimed directly at truck operators. Effectively by-passing the OEM, it urges buyers to specify Cummins power in whatever make of chassis they might favour.
Cummins engines, specifically the 15-litre ISX unit, now in its upgraded form, potentially compliant with EPA 2010 emission limits, remains available in class 8 Daimler, Volvo and Paccar group chassis. Much as they would like to be 100% self sufficient in heavy-duty diesel power, those manufacturers know that if one of them was to delete the Cummins option, buyers would be tempted to go to another truck maker where the ISX was still listed. It could be argued that there is, in fact, a kind of ‘deterrent balance’.
Only Navistar has struck off its Cummins ISX option, for reasons covered previously in AutomotiveWorld.com analyses, relating to the proprietary engine maker’s switch to urea-fed SCR technology for NOx emission control.
Like Navistar, Cummins has also been (and remains) a major producer of medium-duty on-highway diesels, with capacities between 4 and 9 litres. Those engines, which have been manufactured in large numbers over the last six or seven years, necessarily complied with EPA 2004 and subsequently EPA 2007 emissions legislation. Many were certified at levels, on NOx especially, well below the statutory limits, for which Navistar and Cummins were rewarded with the issuing of emission credits that they were able to ‘bank’ against the requirements of future legislation, notably those of EPA 2010.
That accumulation of emission credits has allowed Cummins – and Navistar – to continue selling EPA 2007 standard engines beyond the January 1 2010 deadline, which saw much tougher NOx and PM limits come into force. Critically, the NOx limit was effectively reduced by 60% from 0.5g/hp-hr to just 0.2g/hp-hr. This has required immense additional technology and cost to achieve.
new class 8 truck sales gradually pick up from the severe downturn during the next year or so, both manufacturers will be keen to take maximum advantage of their available credits
With its late-in-the-day decision to add SCR to its existing EGR (exhaust gas recirculation) installation for NOx control, coupled with other refinements, especially the introduction of its in-house XPI high-pressure fuel system, Cummins could almost certainly meet the 0.2g/hp-hr limit required for full EPA 2010 compliance. But thanks to the availability of those aforementioned credits, Cummins is able to programme the ISX engine controls – specifically in regard to injection timing – to emit up to the EPA 2007 limit of 0.5g/hp-hr.
The less demanding ‘0.5 gram’ limit allows net injection timing to be advanced, which in turn benefits fuel economy and also, incidentally, reduces PM emissions. Among Cummins’ North American heavy-duty engine rivals, Navistar enjoys the same emission credit benefits, but without SCR’s fuel efficiency advantage, while the other contenders gain in fuel consumption terms through their use of SCR. But, without the aid of credits, they must apply some fuel sapping injection-timing retardation to comply fully with the ‘0.2 gram’ NOx limit in those EPA 2010 rules.
It is not clear how long Cummins’ and Navistar’s bank of emission credits will last. It will depend to a large extent on the number of ‘credit assisted’ engines that are certified, which itself is dependent on the rate at which the North American truck market recovers. As new class 8 truck sales gradually pick up from the severe downturn during the next year or so, both manufacturers will be keen to take maximum advantage of their available credits. In Cummins’ case that is likely to manifest itself in quite justifiable claims of markedly superior fuel economy over its competitors.
The opinions expressed here are those of the author and do not necessarily reflect the positions of Automotive World Ltd.
