Thanks for details!
There seems to be a history here, with metallurgy playing a role. As Pneudyne pointed out in earlier posts to this string, Alco had ... issues ... with crankshafts for the 244 engine, that seem to have turned in part on the difficulty of finding a supply of adequately robust, forged, crankshafts.
((((QUESTION: Did EMD have comparable difficulties? I can think of a couple of reasons why they might have had an easier time of it, but as a non-engineer I don't know whether or how much they mattered: (i) EMD's engines, in the 1940s/1950s, had a lower per-cylinder output than Alco's (12 Cylinder 244 gave the same power as 16 cylinder 567), so the energy transferred by a pair of EMD pistons to a 567 crankshaft throw was less than that delivered by a pair of Alco pistons to a 244 crankshaft throw, and (ii) EMD's engine was two-stroke, so every down-stroke of a piston was a power stroke, whereas Alco's was four-stroke, so only every other downstroke was powered: as a consequence the force exerted by Alco pistons on the crankshaft at each POWER stroke would have been higher.))))
Comparing the Alco 538 (family) and others with the Sulzer LDA28C used on British Rail Class 47 (and a few other classes) is instructive. The 9" bore, 10.5" stroke engines (Alco 241, Alco 244, Alco 251, CB/GE FDL) have a cylinder displacement of 668 cubic inches. The Sulzer engine is MUCH bigger: per-cylinder displacement of 1352.3 cubic inches (28cm bore, 26cm stroke). This isn't quite as big as the Alco 538 (1552.7 cubic inches), but it's closer to it than it is to the postwar Alco engines. (For comparison, the current GE GEVO engine has 970.6 cu in per cylinder.) I haven't found weights to compare, but the Sulzer engine seems to be much, much, lighter: perhaps a matter of not having a cast iron frame.
((((QUESTION: Does anybody here know just how much lighter the welded-frame 540 would have been than the standard 539?))))
Now the history. Sulzer (headquartered in Switzerland, though Sulzer engines were built by subsidiaries or licensees in many countries) had been in the Diesel engine business for decades, and had built V-configuration engines early on. They abandoned the V-type for high output engines, switching to the dual-bank form, in the 1920s. Apparent reason: crankshafts! They didn't think a single crankshaft, made with the technology available at the time, could handle the power of a big engine suitable for mainline railway purposes. SO: Alco's people in the early 1940s, exploring the possibilities of a dual-bank derivative of the 538 instead of a V-configuration, were following an established precedent. And, given the saga of 244 crankshafts, were probably reasonable in doing so.
Crankshaft design and metallurgy. of course, eventually improved. By the time (late 1950s) of the British Rail modernization plan, American locomotive engines were happily taking high power on single crankshafts. (Given the different conventions for stating power ratings, I think the 16-244 engine in Alco's 1955 Dl-600A had a higher output than the LDA28 in British Rail's Class 47 of the 1960s.) Sulzer themselves had gone back to the V-configuration for more modern diesels, supplying them for locomotives of the French railways. Why British Rail insisted on an engine design originally adopted for 1920s crankshaft metallurgy I'm not sure...
(References: British rail fans and technology historians are maybe a bit more with it than American. Googling "Sulzer LDA28C" I got a number of hits, including "fan" websites with lots of interesting history, much more than what I've summarized here.)