Interesting!
Sorry I don't nick-name my engines, but I do make up my own nicknames I keep to myself for people I see in the gym regularly, but do not know personally. I know it sounds weird and if you're not a gym rat you may not understand, but if you are it will probably make perfect sense. People you see regularly with certain habits, mannerisms, characteristic, or appearance, or who remind you of a certain fictional or historical character or celebrity, but who you don't know personally. I know I've been doing this for a many many years.
It is a way to give a proper name to someone, or in the case of your locos something, that is familiar by identifying it with a meaningful (at least to you) name.