Navistar: The changing face of MaxxForce

Could Navistar International be heading towards dropping its mid-range diesel engines following a quiet rejig of its nomenclature?

It seems the corporation, which has some engines in transition, is dropping its MaxxForce brand and replacing it by N, as in N9, N10 and N13. Presumably N stands for Navistar.

On its website, International declares its engine portfolio as: the V8 MaxxForce 7, and the I6 Cummins ISB6.7, N9, N10, N13 and Cummins ISX15. The erstwhile 10.5 litre MaxxForce 11 – like the N13 a diesel with German MAN roots – no longer appears in the engine line-up.

The power outputs of the revised six-engine International line-up are given respectively as: up to 300 bhp, up to 300 bhp, up to 330 bhp, up to 350 bhp, up to 475 bhp and, lastly, up to 600 bhp for the Cummins ISX15.

The N9 and the N10 share the same swept volume of 9.3-litres, but in the case of the N10 although the power output is about the same as that of the N9 the developed torque is significantly higher. High enough presumably to be given different branding, albeit confusingly.

Thus the N9 develops 223-246kW (300-330 bhp) and 1,166-1,288Nm (860-950 lbft) torque whereas the N10 develops 230-260kW (310-350 bhp) and torque within the range 1.425-1,566Nm (1,050-1,150lbft).

Industry observers are questioning whether Navistar can justify retaining those 9.3- litre in-house engines in the longer term. They are, after all, stretched derivatives of the company’s venerable 7.6-litre DT466 unit which, about two years ago, was relegated to ‘optional’ status in middle-weight International trucks and buses, being effectively displaced by the outsourced 6.7-litre Cummins ISB unit.

Clearly, Cummins would be only too pleased to supply Navistar also with its 8.3-litre ISC and/or its 8.9-litre ISL engines, the latter offering comparable performance to the in-house N9 and 10.

The Cummins units are more modern in design and, almost certainly, have benefitted from much greater R&D investment to achieve EPA 10 emission compliance. That will inevitably have translated into superior fuel economy vis-à-vis Navistar’s own 9.3-litre.

Admittedly, Navistar has been compelled by EPA legislation to update its remaining in-house diesels (including the MAN-based N13), chiefly by the addition of SCR (selective catalytic reduction) after-treatment to hold down oxides of nitrogen (NOx) emissions. But, bizarrely, in the eyes of many outside observers, the SCR package has been engineered by – guess who? – Cummins.

So, one is tempted to ask, perhaps mischievously, whether Cummins’ SCR engineering team were influenced to put as much effort and know-how into the Navistar programme as they did when adding SCR to their own company’s engines. Because, after all, there is undeniable commercial competition between the two makes of engine in International trucks and buses.

Whether the Cummins-engineered SCR installation on the Navistar engines is as good as that on the equivalent rival engines from Cummins’ own stable will be judged, to a large extent, by the respective fuel consumption returns. The N9 and N10 will be hampered in that respect by the dated design, as such relying on more EGR (exhaust gas recirculation) and/or more injection timing retardation. It is therefore likely that the rival Cummins ISL would prove more frugal.

On its website, Navistar notes that he N9 and N10 engines are available on the International DuraStar 4400 and WorkStar MRD vehicles. The company already offers the Cummins ISB 6.7-litre engine in its DuraStar medium duty trucks.

And, in addition, claims that built on the "proven I-6 platform of reliability and durability, the N9 and N10 SCR engines offer a fuel economy improvement of up to 8 per cent compared to the previous generation engine, adding more money to operators' bottom line".

The fuel consumption issue, now less important for truckers than it was, thanks to the decline in crude oil and hence diesel fuel prices, is nevertheless becoming a key future legislative issue, because of impending standards on greenhouse gas (GHG) emissions, due to come into force in 2018.  

It all leads inevitably to speculation that Navistar’s days as an engine manufacturer could be numbered. That speculation could be extrapolated further to envisage an eventual take-over of Navistar by Cummins, creating an entity which would pull those two all-American companies into line with the rest of the North American medium- and heavy-duty truck market – as another vertically-integrated producer, alongside European-influenced Daimler, Volvo and Paccar.