Spray transfer mode GMAW is a high(er) energy and heat welding process. The solid wire turns into molten droplets of metal as it continuously feeds into the arc zone. Very fluid welding puddle so much so that it is NOT usable in all positions but only in flat position unless you have a machine that can do pulsed spray mode (not counting Jody from weldingtipsandtricks recounting how he sort of did manual pulse spray), HOT, continuous arc, uses higher voltage and higher amperage than short-circuit transfer mode, uses shielding gases like 98-2 argon-O2 (often used for spray mode transfer on stainless steel) or 95-5 or 90-10 argon-CO2 for steel. Makes a hiss noise during welding and not the usual sizzling bacon noise that short-circuit transfer mode makes.
Unless you have pulsed spray mode, for 'thin' steel you are usually using short-circuit transfer mode GMAW. The wire electrode touches the workpiece, shorts out and heats up, then burns back and makes an arc, and repeats. At about 60 times per second, hence the sizzling bacon sounds.
You can look up more details on the modes online. Videos, descriptions, examples, etc.
By the time you put a 60-80 lb modern inverter welder on a cart with a gas cylinder you are about the same footprint as a 250+class big welder. Just not 150+lbs of welder + gas cylinder weight to move around.
The 250+ class machines are all usually 230-240V (or the industrial versions that can sometimes be bought in the higher voltage versions 440V or 3 phase).
The modern inverter 215 class machines are often usable on 120V at lower amperage settings and 230-240V at the higher settings. I consider them semi-portable, as you have the machine and the wires/cables/torch and the gas cylinder to move around.
Not portable like a lunchbox 10-25lb inverter stick/TIG welder with a shoulder strap.
The Miller MM220 multiprocess machine is 220-240V only. Expensive though, up in the $4k range, similar to the 250+class MIG machines.
Red, blue, ESAB yellow, maybe HTP or Primeweld would be what I would look at. Although some other brands have gotten better, they usually don't have the support and parts that the big names have.
I'm not a good enough welder to want to fight with an off brand machine and wonder if it's the machine or me causing 'issues'. And the whole support and parts thing.
Sheet metal and 'thin' steel up to ~1/4" or so and the modern 215 class inverter welders should cover that with solid wire GMAW. FCAW-S or FCAW-G ( aka dual shield) can usually be done with the modern inverter 215 class machines, and those wires run 'hotter' than solid wire short-circuit transfer mode GMAW and can let you weld a little bit thicker steel than solid wire short-circuit transfer mode GMAW.
Check the wire details though, some 'general purpose' FCAW-S wires do NOT have rated impact properties. Not that they are 'bad' wires, just that they don't have to meet impact properties in that classification category.
Also Double check any racing sanctioning rules for welding. Some organizations have rules about those sorts of things.
