Just a point of interest. An electric motor on a compressor that plugs into a standard 120v outlet can not produce anymore than 2.5 HP period. Unless the company is violating all the electrical codes and safety standards in the country the most current the device can draw is 15 Amps. 15 Amps converts to 1800 Watts which conversts to 2.5HP.
Most new construction has 20 Amp service which would allow 3HP but to use the full 20 Amps requires the plug on the device to be different (one of the blades is 90 degrees to the other).
The way they come up with these high HP numbers is they do what is called a lock rotor test where they prevent the motor from turning and see how much current is drawn. For a 6HP number it would be 37 Amps. This test is performed as a requirement for UL safety certification, they do it to ensure something bad does not happen like bursting into flames. It has no bearing on how much power the motor is producing when it is running.
So what I am saying is do not even pay attention to the HP rating on a 120 volt compressor since no matter what it says it will only produce 2.5 HP when it's running or you will be popping breakers all the time. And this also means that a 120 v compressor is not going to be suitable for running most air tools.
A large capacity tank will give you more run time before the compressor kicks in but you will have to stop using the tool until the pressure comes back up.
The only thing to look at is the cfm rating at pressure compared to the tools needs.
