A steam locomotive is known to be able to pull more then any pure combustion engine locomotive. (Uncited)
Why didn’t oil fired steam locomotives take off?
This started when I watched: https://www.youtube.com/watch?v=Hszu80NJ438
During the runtime, it mentioned oil fired retrofits.
I search it up, and found one.
It was an overview video of a modern retrofit, and it seems to not be too difficult to retrofit, even using the same steam blaster to spread the oil in the smoke box: https://www.youtube.com/watch?v=Up1UaMVnv4M
For anyone scrolling by and curious about this, this is caused by the combination of physical and electrical resistance. In a typical engine, RPM and torque go up together because it requires more force to get to those higher RPMs (IIRC this is called positive correlation). In a circuit, you have to kind of convince the electricity that it would be better off somewhere else (by connecting to a ground, this is due to electrical resistance), so you have to give it a heavy upfront load to get it going which causes a lot of torque due to the physical resistance