Smallest compressor Available that works?

I have a 256 combo unit and am building a kind of large welding cart and welding table in my garage . I see that the plasma takes 60 PSI at 5.3 CFM at max amps ,but I am looking for a small compressor that I might be able to just put on my cart. I see that most thinner materials are not needing 60PSI and the most common material I will be cutting is .125 to .185 steel. So with that said what would be the lowest CFM and PSI for that range , I have seen some smaller compressors that might fit my cart but not sure how much air I will be needing. I do have a larger compressor but it happens to be on the same 220 circuit as my welder and if I could find a smaller compressor that would do the job at 110 volts then that would be helpful for what I need. And so far I have not even used the plasma cutter , just the welding. So any help would be great.
Gary

Gary,
Stick with the guidlines. You need the cfm. You'll need it. Our cfm ratings are quite conservative. One thing that most people fail to realize, is that you also need reserve. I just had a customer call in to tell me about the unit would quite working periodically while he was cutting. I asked him what size compressor he was using. He said a 4 gallon pancake compressor. It was barely putting out 2 or 3 cfm. He was only cutting in short bursts and the low pressure switch would stop the unit because of the lack of reserve and the compressor would not keep up.

As for "lowering" the pressure, I don't want to get a rumor started here. Lowering pressure is helpful in some circumstances, but our torches run a relatively low pressure to begin with. Most people make a mistake with running too low of pressure. The torches cannot cool themselves and electrode life gets shortened if operating too low of pressure. Typically, never go below 50 psi, and most applications will require 60 psi.

Lowe's has a 110V twin cylinder 5.7 cfm @ 90 psi with 30 gallon capacity. Its portable and works quite well. I personally use this with up to 80 amp cutters...It does run a lot, but it can keep pace in most circumstances.

The largest compressor you can run on 110 is 2hp, Northern tool has an IR 2hp with a 20 gallon tank for $499 @ 5.5 CFM @ 90 psi. I have almost the identical one under a different brand, it works fine for the PP 50 but I will be adding an extra tank to increase air capacity when I hook up my PP 80 to my CNC table. A 15 amp breaker on 110 volts can only handle 2 HP or 1500 watts as 1 HP = 750 watts. Those small air nailer compressors can do a cut but not a long one due to the tank size. Rule of thumb on plasma air requirement is: amps divided by 10 minus one. For example 60 amp cutter requires 5 CFM, etc.

Thanks for the info Mark & Geezer,
I have a 5hp 25 gallon compressor but it is on the same circuit as my welder soooo I wanted to see if a smaller compressor that would fit in my cabinet would work, But to be safe I am just going to switch the wiring around , I have a spare 100 amp breaker that I use for my backup generator that I can connect to kinda easy so I guess that will be the ticket and wont have to worry about low air cfm .
Thanks Again
Gary