RK215 wrote:Swift obsessor wrote:On that Cummins L10.Did Cummins actually design the L10 engine specifically for the British market and was it all done in America?
Am I reading it right that Cummins looked at the Gardner's economy when they came up with their engine?
The Gardner was always seen as a premium engine yet was always eclipsed in the power figures by the Cummins L10 in the MCW Metrobuses.
Was the L10 just as durable as the venerable Gardner product?
I understand that the Gardner range were a very old design being carried on by the 1980s whereas the L10 would have been much more recently designed altogether I assume.
What about the Rolls Royce diesels used in some MCWs as well.Why weren't they as prolific as Gardner /Cummins??
You know, many years ago I did read about the development history of the Cummins L10, but I don't recall enough of the detail other than what I have already said to do justice to your questions. I'm not sure that I've retained much in my library on the L10, either, but I'll check when I'm back home and post again, and also comment upon Gardner and Rolls Royce.
As it happens, I have retained very little material on the Cummins L10 or the Rolls Royce Eagle series engines and their derivatives.
However, I do have an article from “Buses” magazine of January 1996 that does provide a brief historical perspective. It records that it was in 1982 that Cummins announced its intention to break into the UK bus market in a big way with its new L10 engine, in which it had invested STG100 million in development costs. Although compact, “complex” (insofar as it had 4-valve heads) and turbocharged, the L10 soon demonstrated that it could equal the Gardner 6LXB in terms of reliability, longevity and economy, whilst easily outperforming it. And it won on emissions, too. The Gardner 6LXB couldn’t meet the Euro 1 requirements.
Even so, the UK bus market would have been but a small proportion of the intended market for the L10. The largest market was probably the US on-highway truck sector. Cummins no doubt saw that with the progressively increasing specific power outputs that came with higher boost pressures, which in turn, coupled with intercooling made meeting emissions targets easier, there was a place for a smaller displacement, but nevertheless robust engine to cover power outputs up to around 300-350 hp. At the time, the Cummins 14 litre N-series was dominant in the US Class 8 truck market. Caterpillar’s mid-1980s offering, the 3406, was even larger at 14.6 litres.
I guess one might conclude that Cummins took an holistic approach to L10 design, factoring in multiple end-user requirements including, but not limited to the British bus requirements.
Meanwhile, I haven’t unearthed anything more on the Cummins V6-200, but I have found a brochure on the smaller V6-140 and V8-185 engines. The V6-140 was also a 90 degree, three-throw engine, evidently without a balance shaft. At least, there is no mention of it, nor any sign of it in the diagrams.
In respect of Gardner and particularly its late history, the excellent book by Graham Edge is the best source. I understand that a second, updated edition is about to be released. From the 1970s, Gardner rested on its laurels somewhat, having had a seller’s market for so long. Its late engine models were underdeveloped. Still, with the benefit of hindsight, it seems unlikely that such a relatively small organization could have mustered the resources to keep up with the “big” engine builders as development costs escalated, even had the intent been there.
Cheers,