How in HECK to you figure HP on a B&S engine?

I remember the lawn mower HP wars around the turn of the century.

3.5
3.75
4

then

6
7
8

...and then somewhere they snuck in the substitution TQ rating.

Some even just put arbitrary numbers on them.

Giant font "8", then a tiny "th generation" or "series" next to it.
Unless you read the fine print, you thought it was 8 HP.
as a rule of thumb, i consider anything measured in CCs as junk