(14 Aug 2020, 12:03 pm)streetdeckfan wrote But wouldn't having an extra, taller gear mean less strain on the engine as it could go faster at a lower RPM?
That's exactly what you see in cars, particularly in the past you would see the same engine with a 5 speed and 6 speed gearbox, and the 6 speed would pretty much always be more efficient, and smoother on the motorway as it allowed the engine to sit at pretty much idle at 70mph.
It's why you now see cars with 9 or 10 gears. When was the last time you saw a car with a 4 speed gearbox?
It doesn't, however, take away from the fact that a larger engine will be under less stress when coupled with the same gearing.
My, admittedly limited, understanding of engines tells me that a higher capacity engine (i.e a 6.7L) will generally produce the same amount of power as a lower capacity engine (i.e 5L) at a lower RPM if gearing is the same. Therefore as well as it having more at the top end, it's also under less stress for the most part.