You're partially right.......
746 watts per HP is assuming a perfect 100% efficiency. I think we all know that nothing is 100% efficient. The watts/HP conversion is a law of physics. It's a known fact that it takes at least 746 watts (mechanical or electrical) to equal 1 Horsepower.
In a US home, the maximum wattage an appliance should draw on a single 120V outlet is 1500w (although you see hairdryers at 1875w which is literally 15 amps!). At 1500w, the maximum horsepower you can develop (for ANY motor and assuming 100% efficiency) is 2.01 HP.
Mind you a motor is rated at full load. If the motor isn't fully loaded, it will run faster and actually draw less current (due to being more in sync with the AC sine wave). Less current at a given voltage means less wattage being drawn. Less wattage means less horsepower.
It's a rule of science and physics that you simply cannot draw more than 2.01 horsepower MAXIMUM (and assuming you're in a perfect world) from a residential 120V outlet.
Appliances that draw more than 1500w from an outlet are actually in violation of many fire protection laws. The accepted maximum for any circuit is a draw of about 80% of the circuit's capacity by any one appliance.
Assuming a nominal voltage of 120v, that means 1440w as a maximum. That's why the biggest vacuum motors you see in the US are 12.5 amps to comply with fire protection codes.
Resistance appliances are a little different.....as the voltage falls, so does their current draw. That's why they can get away with the 1875w. As the voltage drops in the wiring in the house under load, the voltage falls in the appliance reducing the wattage load. Sort of a self-balancing thing.
Inductive devices like motors however, will draw more current as the voltage falls. They'll still be the same wattage, but it's the current rise that does damage to wiring and blows fuses.
So no.....in the US on a 120V circuit, your blender doesn't produce 2.25 HP. It physically can't produce more than 2.01 HP absolute maximum on a 15 amp plug. Assuming 90% efficiency it can't develop more than 1.8 HP.
If you were lucky enough to have a 20 amp circuit (which appliances rated for a 20A circuit must explicitly have a tag on the plug saying so with large warning letters) then the maximum you can develop (in theory) is 3.21 HP. Assuming 90% efficiency again, the maximum you can actually make is 2.89 HP. That's assuming you have that circuit fully loaded. If the appliance follows rating guidelines and only loads to 80% of the circuit, you can't get more than 2.6 HP out of it absolute maximum at 90% efficiency.
Rules of physics.....
Turn the machine over and read the nameplate. Multiply 120v times amps and it'll give you the wattage. Divide that by 746 and you'll be greeted with the absolute maximum power that machine could possibly produce (if it were 100% efficient). If you want a more realistic answer of it's horsepower rating multiply your theoretical result by .85 or .9. THAT is your actual peak horsepower. NOT what the manufacturer "claims" it to be.
Lovely to look at, pose beside and sit in. That's why I go to the new & vintage Car Shows and Auto Museums where I find them across the nation. You get to look, touch and even sometimes sit in them...without the onerous responsibility of ownership and car payments.
