Dont know if this info is right or not but gives me something to start at.
copy paste
It is hard to convert cc to H.P. on the engine specs they usually now tell you max kW at what rpm
1 hp = .75kW,
and 1 hp. = 550 foot pounds per second, of torque.
On a mower or for that matter a outboard motor where you are spinning a blade or propeller torque is more important than horse power.