"I'm like Tim the tool man ,,, Horse POWER ..."
It's a sewing machine, not a tractor pull. If it's raw horsepower you're after, you'll need to go industrial.
I think you may be missing my central point, which is that horsepower doesn't mean anything if you can't get it to the rear wheels. The 15-91 has plenty of punch, which any number of people who use that machine can tell you, but that doesn't mean anything if you are not able to figure out how to get it to the rear wheels.