[Bimmer]

I'd really like to know the details of these boost systems. The water injection systems are pretty straight-forward, but what about the others? Are we talking about additional supercharger boost? If so, additional fuel would likely be used to keep combustion temperatures down in the cylinders, lacking another substance to perform that function, if in fact cylinder temperatures had proven to be an issue on that particular engine under boost. This would likely result in smoke, but also would probably only be usable within a fairly limited operating range (high RPM, high airspeed) and the engine wouldn't stand it for long. Even so, each engine is going to react differently, and each boost system is going to be different in the details. I would think that pretty solid evidence, as some have posted (albeit anecdotal), would be needed before applying boost smoke effects to a given engine or engine family if one wanted to be historically accurate.