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Hey everyone! I just picked up an old sanborn gas powered compressor. It’s 3 HP and 14 gallon with a twin cylinder compressor, but only advertises 3.4 SCFM at 40 PSI. I find that surprising because I expect more like 9-10 SCFM out of a 3 horse compressor. I want it to use with an impact wrench, tire inflater, air gun and possibly air hammer. I won’t be using the tools for long durations, probably just short bursts. The things I’d do mostly would be removing lawn mower blade bolts or shaft adapters. But I’m not sure if I can because you’re supposed to have at least 4-5 SCFM for an impact wrench, and that’s only at like 25% duty cycle I’m pretty sure. Does anyone know why it’s rated so low on SCFM? Will it be good enough? Thanks!
 

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I like to stay with at least 4 times the cfm of an impact on an air compressor.
and i like at least a rating of 40cfm @ 175 psi with a 40 gallon or larger tank.
you could try running a extra 20 gallon tank with at least 3/4 npt ports... but it will run the heck out of the little compressor..
you need a 100% duty cycle unit...
3/8 air line is the bare min for an good high power thunder gun 1/2 inch impact at 25 feet long.

yea there is a lot of jina compressors out there right now...
weird ratings as well...

just a note good compressors start at $400.00 and up.
belt driven 2 stage is a good way to start.
 

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Tyler_Frankel,

A gas motor HP is not rated the same as an electric motor HP the torque curves are different at different rpms.
Some debated rules of thumb (found at cranky Mech engineering site) 1 hp electric = 3 hp gas

Stephen


Hey everyone! I just picked up an old sanborn gas powered compressor. It’s 3 HP and 14 gallon with a twin cylinder compressor, but only advertises 3.4 SCFM at 40 PSI. I find that surprising because I expect more like 9-10 SCFM out of a 3 horse compressor. I want it to use with an impact wrench, tire inflater, air gun and possibly air hammer. I won’t be using the tools for long durations, probably just short bursts. The things I’d do mostly would be removing lawn mower blade bolts or shaft adapters. But I’m not sure if I can because you’re supposed to have at least 4-5 SCFM for an impact wrench, and that’s only at like 25% duty cycle I’m pretty sure. Does anyone know why it’s rated so low on SCFM? Will it be good enough? Thanks!
 
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