Gotta Luv HP Ratings

[Downwindtracker2]

Years ago I bought a Speedair compressor , they claimed 5hp. Mmm, my 3 hp table saw also used 15amps. I understood it put out 10 CFM, which was more important number. The compressor pump died, so I replaced it with a Rollair 3-5hp one and had it turning to get 15 CFM. When I first used it, the motor got warm, but since the pump was Chinese I thought it would wear in fast, it did. But,I finally had enough air. One year later the motor quit. Surprising how the pump, the control and the motor all died within a year. My two previous electric motor repairs attempts hadn't turned out too successful so I bought a Princess Auto 5 hp drip proof motor. By the spec sheet, full draw is 19.56 Amps . None of these hp numbers make much sense.

 

[Superburban]

Yea, it seems shop vacs, and air compressors are so efficient, that they can get 5hp, Using the same current other things draw, for a 2 to 3 HP motor.

IIRC, someone said that they are using the amp draw with a locked rotor, and converting that to HP. Thats why the actual plate on the motor will say somwthing like "SPL", "5SPL" or "3SPL" There is legal requirements as to what has to be on the name plate, and if they use the real HP, then the air compressor maker could not claim the higher number.

 

[Ulma Doctor]

HP is a figure that can be bent depending on who is interpreting the information.
it appears that most manufacturers are using theoretical horsepower in their computations.
i say theoretical because the reality is that you will never see the full HP potential of the motor, as rated, in service.
1 HP = 746 Watts in the real world, or 736 watts in the metric world

 

[benmychree]

Chinese HP, V/S real HP?

 

[BROCKWOOD]

Tank size is misleading too.

 

[hman]

Chinese horses are of smaller stature than Western horses.

 

[Liljoebrshooter]

There were class action lawsuits a few years ago for this. I had a air compressor that was included in it. They claimed 6hp on the motor.
If I remember correctly, i received a coupon for a few dollars off the purchase of a new compressor.
Sears did the same with table saws.
Joe Hynes

 

[Bob Korves]

As long as nobody in power cares enough about truth in advertising to do something about it, nothing will change. In the meantime, Caveat Emptor... Like a good friend once told me, you can buy most anything in the world for the cost of a good steak sandwich.

 

[JimDawson]

My 5hp compressor actually came with a 5hp motor. ~23 amps at 240V, but I bought it about 35 years ago. A customer gave me a much newer ''7hp'' Craftsman compressor with a bad motor, it actually had a 5hp motor on it.

My Rigid shop vac says 6.5 peak HP on it Not sure what that means, I think it's about 8 or so amps at 120V, just over 1hp. Even my Porter Cable ''3 1/4 hp'' router is way overrated, more like about 2.1 hp.

Bottom line is look at the max amps on the label to figure out what you are buying, the marketing types are always trying to outdo each other.

 

[Downwindtracker2]

Hman's explanation does make the most sense , except the Dayton Speedair is American made. Maybe they used ponies? On a similar vein, you see a big American flag on the vertical 5hp compressors, there on top is the same Chinese made 3 cylinder pump, control, and now motor I have.