I was kind of bummed last month. I was looking for an Air Compressor at various stores like Sears and HD and the marketing on them is very confusing.
THey are rated as " HP 2.0 running, 6.2 peak" What does that mean?
The only way you can only evaluate them is to check the scfm at 40 and 90 psi. I saw quite a few "Huge" units with puny output; ie a 3 hp motor on a 60 gallon tank.
I ended up buying a used 220V 5 HP Sears 20 gallon unit from the 60's with some real scfm and a new GE 5 hp motor about the size of a SAAB engine for $50.00!
I'm in the process of rebuilding it and sticking it on my 30 gallon tank.

Statements like "2.0 running 6.2 peak" mean that the manufacturer is being honest with you about the true output from the motor. Less honest manufacturers would simply call it a "6.2 HP" compressor. That's the max horsepower, as I'm sure you know, which can't be generated unless there is a whole lot of torque being developed, which probably can't happen when used for a compressor.

You're right, the SCFM figures at 40 and 90 are comparable, and since that's what tells you if you can use it for a particular application, these figures are all that matter. 90 for air tools, 40 for a spray gun.

Congrats on your find. Sounds like it should be a decent setup.

Do yourself a BIG favor and DON'T buy one of those sears direct drive compressors. Those things are VERY NOISY!!! I have an old sears 1.5 hp,belt driven compressor that has lasted me 30 years with regular useage.

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I recently replaced a 2hp direct-drive compressor with a "5hp" C-H belt-driven model (really about 3hp). It's much quieter than the old 2hp, and can drive a paint gun at 100% duty-cycle.

Ditto on the noise of direct drive air compressors. I have one of these http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47065
and I usually leave the garage when it kicks on.

we have on in the shop.. our old one a 50's vintage broke the belt and the middle school didnt need their air compressor which is a direct drive... i plugged it in and let it build pressure.. frign loud.. i went to go do some work hooking it up to the plasma cutter to get the air pressure correct for it. it turns it self on to replenish the pressure.. scared the crap out of me.. but the ole one doesnt have the capacity as the new one... ill fix the old one because its good ...

funny thing, we have all these new tools in the shop, drill presses, band saws, scroll saws.. but i end up using the vintage 50's-60's craftsman drill press and band saw over the others.. why? because.. they dont make em like they used to.. my teacher broke some part on the newer band saw.. this part cruicial to how the work surface is angled broke...it was made of plastic..not metal like the one on the craftsman...pfft

http://mgaguru.com/mgtech/tools/ar101.htm

Carra,

If you are using an air receiver from the 60's you might want to make sure that the bottom is not rusted out. These tanks will not explode if they rust through but you might invest a lot of time and money in a unit that is scrap.

When I bought mine I was only concerned with how many cfm it would put out at 90 psi. It's an Ingersoll Rand, just a single stage, 230 volt unit with 60 gallon tank, puts out about 11.5 cfm at 90 psi. I don't see anywhere on unit that indicates hp.

It good for spray painting, and most all air tools. Kind of weak for air hammer and useless for die grinder.