Cummins ISX11.9 engine prompts industry speculation
By: Alan Bunting, Tuesday, February 24, 2009, AutomotiveWorld.com
Manufacturers are sometimes inclined, for PR reasons, to hide away significant developments in the middle of outwardly bland pronouncements. A classic example is the recent, apparently innocuous, press release from diesel engine maker Cummins. It is headed 'Cummins reaffirms readiness for EPA 2010 regulations', suggesting that its essential content has been disseminated previously.
But tucked away in the fourth paragraph is some real news – that Cummins' EPA 2010 line-up of truck and bus diesels for the North American market will include the 'ISX11.9', an all-new 'medium bore' engine – a 'clean sheet design' – aimed at vocational (municipal) and similar cruiserweight applications. As such it will replace the venerable 10.8 litre ISM, whose origins can be traced back to the then ground-breaking Cummins 10 litre of the 1970s.
No technical details of the ISX11.9 are revealed other than the implied swept volume of just under 12 litres. A request to Cummins from AutomotiveWorld.com for more information on where it will be manufactured, its power and torque ratings, bore and stroke dimensions and weight, as well as the finer points of the design, was met with the response that nothing more is being revealed at present.
So the way is open for informed speculation. It seems likely that the first part of the new engine's designation has been 'borrowed' from the fairly well-regarded 15 litre ISX which, in its upgraded EPA 2010-compliant form, is being subtly redesignated as the ISX15. It is a break with precedent for Cummins engines of two different cylinder sizes to carry the same three-letter nomenclature.
Truckers who don't look too closely at the ISX11.9 specification might therefore assume that it is derived from the 15 litre and, as such, will inherit its reputation. In fact the only features the two engines have in common are their so-called subsystems: the Cummins-Scania XPI high-pressure common-rail fuel system; Holset 'moving sidewall' variable-geometry turbocharger; SCR-plus-EGR NOx emissions control; and the same electronic engine management system.
In the absence of any indication from Cummins to the contrary, it is reasonable to assume that the ISX11.9 is the engine which has been developed – and is being manufactured – in China under a Cummins joint venture with Dongfeng Motor Corporation announced in 2005. At the time the engine was said to be of nominal 13 litres capacity. But no diesel manufacturer would simultaneously develop a 'clean sheet' 13 litre and a 12 litre, unless one was a derivative of the other. In the absence of any indication from Cummins to the contrary, it is reasonable to assume that the ISX11.9 is the engine which has been developed – and is being manufactured – in China under a Cummins joint venture with Dongfeng Motor Corporation announced in 2005.Output figures for the 13 litre Dongfeng joint-venture engine were quoted at 'between 400 and 545hp'. A shorter-stroke or sleeved version with a swept volume of just under 12 litres could be expected to develop up to about 500hp, a respectable advance on its ISM predecessor whose maximum output was around 440hp.
There is some surprise that Cummins will apparently not be offering the 13 litre variant, as originally announced, in its EPA 2010 line-up, so as to compete more directly with the in-house engines of around about that capacity being listed by US OEMs. Those include the Detroit Diesel DD13 already available from Freightliner, the D13 from Volvo and the DAF/Paccar MX to be fitted by Kenworth and Peterbilt. Only the Navistar MaxxForce 13 (aka the MAN D26) is smaller, at 12.4 litres.
Given the fact that all Cummins' North American heavy truck OEM customers, without exception, have now set themselves a medium- to long-term goal of powertrain self-sufficiency, it is unlikely that the last proprietary heavy-duty diesel supplier would begin production of an all-new engine like the ISX11.9 on US soil. In any case the projected manufacturing volumes, for limited-application class 8 operations, would not justify such investment in new plant and machinery.
It is therefore probable that, if Cummins can persuade end-users to demand an ISX11.9 option from their supplying OEMs, the engines will be shipped in from China, either ready-built-up or as so-called 'short motors', ready to be configured for US chassis with appropriate manifolds, sumps and auxiliaries.
Bearing in mind the patriotic instincts of most American truck buyers, the engine would obviously be badged as a straightforward Cummins product, with any indication of its Dongfeng manufacture as far as possible 'disguised'.
Published on Tuesday, February 24, 2009
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