> What do you need the air tank for?
Even assuming you just vent the excess air rather than starting and stopping
the motor, a tank still allows you to operate tools that take more air than
the compressor supplies, and also provides a buffer for tools that have
large instantaneous air draws (like jackhammers and chisels).
> If you have 58 SCFM (or CFM,
> I have not found anything to clarify on this for this setup)
Should I say it again ? Compressors are *always* in scfm, even when they
don't say so.
Lessee, ISTR a typical bug motor is 1800cc, we should get nearly half that
per crank revolution. A cubic foot is .0283 cubic meters, or 28300 cc, so
it would have to spin at 58 * 28300 / 900 rpm to deliver 58 scfm @ 0 psi
(ignoring VE), or a little over 1800 rpm. However, even if the kit has
components to raise the compression ratio through the roof, the efficiency
won't be very good at 100 psi, so I'd guess it turns more like 3600 rpm to
deliver the rated 58 scfm @ 100 psi.
Throw in the multiplier from scfm to cfm, which is almost 8 @ 100 psi, and
the engine would have to turn some 14000 rpm just to get the free air
delivery. Somehow, I doubt that's what they're doing ...
> The compressor is going to run the same amount of
> time whether you have the tank or not, since your air usage requirements
> will still be the same.
How long do you think the starter would last, if you started the engine
every 10 seconds ? Can you recharge the battery in 5 seconds ?
Exercise for the student : how big does the tank have to be to guarantee a
minimum 60 second cycle time (assuming the motor is started when the
pressure falls to 100 psi, and shut off when it rises to 130 psi. For
simplicity, assume compressor output is constant at 58 scfm.)
Randall
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