An interesting idea that crops up every so often. The brits had this fantastic sounding 3 cylinder, 6 piston, 2 stroke diesel engine locomotive, with a bunch of turbos. It sounds fantastic.
Pollution was problematic, so they went away.
Here's a model that illustrates how it works:
Here's a video that really captures the sound of the Napier Deltic engine:
Sometimes known as the whistler engine.