That seems more like a typo than anything, in Formula jargon the engine is called a "power unit" not plant, not to mention that that a plant is generally a place of industry and not a object (e.g., nuclear plant ...).
In either case, calling a "silnik" a "powerplant" is a very large stretch, where as a "powerunit" would be a more accurate translation since it has the same meaning as a engine/motor.
> Porsche has developed a hydrogen powerplant prototype that can be installed in luxury sports cars and perform as well as a 4.4-liter, eight-cylinder petrol engine
I don't see how quoting random articles proves either or, specially when it comes to specific jargon in a sport or even the original topic here wrt. engine vs. motor.
> This article gives an outline of Formula One engines, also called Formula One power units since the hybrid era starting in 2014. Since its inception in 1947, Formula One has used a variety of engine regulations. Formulae limiting engine capacity had been used in Grand Prix racing on a regular basis since after World War I. The engine formulae are divided according to era.
Quoting random articles should prove the point that the author of that page on the F1 website did not in fact make a typo, as you suggested. The word powerplant is used — fairly commonly, both written and spoken — in motoring journalism in place of the word engine or motor.
I don't find your arguments convincing, for the logical holes I've spotted. I don't think you find my arguments convincing either, so I guess we'll leave it at that.
This can be evidenced[0], for example, in motorsport journalism.
> For more than a quarter of a century, Cosworth’s DFV (and it’s variants) was the off-the-peg powerplant of choice for independent F1 teams
Or of course, in the dictionary[1].
[0]: https://www.formula1.com/en/latest/article/the-best-engine-p...
[1]: https://www.merriam-webster.com/dictionary/power%20plant