Following recent discussion on the venerable 14 litre Cummins and its various outputs, my interest was piqued. During my decent into the triple ewes I came across this site.
https://www.cummins.com/en/in/engines/nt855
I wasn’t aware that over 400hp was offered by Cummins, prior to the Big Cam. It is possible that greater than 400hp was only offered in marine or stationary applications.
Interestingly, we found that with unauthorised tuning above 400hp, the liners tended to chatter. Was this also the case with approved 400+ settings and Cummins accepted that as a trade off for the higher output?
As far as I am aware, here (Oceania) output above 400 was not offered for automotive use, prior to the NTC 444.
Scammell built six Contractor Mk2 heavy haulage tractors only for the home market in 1976. They had Cummins 450 engines, which would have been NTC, as we hadn’t got NTE lumps yet.
In 1978 Scammell trialled two engines, one of which was a Cummins KTA 600bhp and a Rolls V12 at 625 bhp to go in the Commander. Both performed well, but Scammell chose the Rolls in the end.
450 to you was the 444 for us. Cummins chose to call it 444 for marketing purposes, in reality it was 450 as per the spec sheet, but regardless of the marketing fluff, they were a Big Cam (NTC). According to the link, I included, the Small Cam was offered at up to 480hp, I suspect only for marine and stationary use.
The KTA’s predecessor, the KT was popular in some sectors here, rated at 450 to 500hp, until C '90s when Kenworth refused to fit it to non-twin steer chassis, as overloaded the maximum legal maximum for a single steer axle.
I’m confused: didn’t NTC refer to small cam and NTE to big cam?
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Bruce Mallinson of Pittsburg Power recorded his experiences about uprating the 855
No doubt Slartibartfast will, as usual, want to argue ad nauseam that he is right and everyone else, including the design and development engineers, are wrong so that will be another thread ruined.
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NT was Small Cam (retrospectively), NTC was Big Cam and NTE was Electronic.
Oh dear. Not here it wasn’t. The NTC 290, 335 and 350 were small-cam (as you say retrospectively speaking) and the NTE big cam. For a while in between, now I come to think of it the early big cam ones were called NTCE 290 etc. The electronic ones were much later in the '90s - the NTAA etc (Celect).
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Oh dear, I seem to have been labouring under a misapprehension for years, believing the information given to me by a truck mechanic.
EVOLUTION OF THE NT-855 ENGINE (HEAVY-DUTY DIESEL)
Improvements since 1957 in the Cummins NT-855 heavy-duty diesel engine are described. The current model, the Big Cam II, is a turbocharged, four-stroke, in-line, six-cylinder engine with 855 cu. in. displacement. Examples of its application are commercial heavy-duty trucks (bulk of the market), large articulated farm tractors, commercial fishing boats, and generator sets (standby or continuous duty). The NT-855 is traced from its pre-1975 version with a rated speed of 2100 rpm (Small Cam), through the 1975 introduction of the Formula rating in which rated speed was reduced (1900 rpm) while maintaining rated power output, to the 1976 Big Cam–Formula (1900 rpm) and 1979 Big Cam II–Formula (1800 rpm) versions. A 15% fuel economy improvement was realized in the 1975-1980 time frame. Future developments (Big Cam III in 1982 and New Engine in 1984) are indicated; a 10% mpg gain is targeted for the 1984 engine over the equivalent Big Cam II model.
Further research required by me. Apologies for the misinformation.
Looking at that data, it all looks OK to me. I don’t think you are wrong, or it is wrong; I just think the dates and nomenclature have led us to call the same thing by a different name.
The big-cam 855 was available in America some time before it was available in Britain. I’m not sure that the C part of NTC didn’t denote that it was exported or built abroad - I say that because the NTC was first built here as the NTK which specifically meant that it was built at Shotts (UK). Bit of a minefield, perhaps.
The first NTE big-cam engines came to UK at the end of the '70s, although a big-cam 290 was being trialled by Cummins in an ERF unit before this.
I don’t know from where our Cummins were sourced, or even if we had anymore than a distribution facility here. I’ve seen engines assembled from parts produced in countries as far apart as Mexico and England. Presumably this was done to comply with mandated or voluntary local content claims. Final assembly would no doubt define country of manufacture.