Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

@Stoker @Nick
I believe that we nailed it, and Nick confirmed by mentioning that the early case had a much lower hp is due to the boiler pressure limitations in the early days compared to the 100s of psi steam pressure when boilers manufacturing improved.
Ps. Break Horse Power Bhp is the same as hp. A 1 hp is 0.76 kW compared to electric motor.

It wasn’t boiler pressure limitations that changed the hp ratings, but the way they measured it. I tried to find an easy to understand post on SmokStak, but left even more confused 😂 I did however come along this in a long post that would make sense Sipp vs Stuart if they were measured the same way:

“Usually, the brake horse power rating was about three times that of the old nominal rating.”