Why Was the Cummins 555 Not Popular?

Hi,

Why was the Cummins V-555 line not so popular?

My theories are that these engines, which include the VTF-555, were an outgrowth of the V-470 (VINE) and the V-504 diesel engines, all of which are undersquare (with a 4-5/8" bore, the V-470 having a 3-1/2" stroke, the V-504 a 3-3/4" stroke and the V-555 a 4-1/8" stroke).

Here is a video of a VTF-555 in action as a retrofit engine in a 1952 American LaFrance fire engine:

~Ben