Don't know about horsepower but all I know is that I no longer put several layers of
fabric through my Janome 6600. I drag my old Kenmore for that. I think the difference
is electronic vs. mechanical. The electronic ones are more fragile and can get the
timing thrown off.
Here's a review of three heavy-duty sewing machines. Not affiliated but if I were
to buy a machine to replace my Kenmore I would go with the HD1000 or HD3000.
http://grandmalikestosew.com/best-he...ewing-machine/