1) Get the biggest one you can afford.
2) Pay attention to duty cycles. Cheap ones are rated at 40% duty cycle or less and a full day of wrenching or painting will tire them out, see (1) above.
3) Piston pump with oversize motor (2-phase 220/240 V) best, esp. with dedicated plug and VERY short pig-tail.
4) Dedicated circuit on house/shop wiring.
5) Spend the money on a high quality water/oil remover and filter setup.

6) most important, have fun.

Mike!

One warning that has not shown up yet is the noise factor. The diaphragm type (oil-less)compressors make a whole lot of it. Piston compressors are much more pleasent to be around if working continuosly for a long time. i.e. painting.

Paint gun will require much air even the HVLP. I pained a couple of panels on my daughter's car and my Sears 5 hp 26 gallon compressor kept up, but ran almost continuously. Don't forget the annoying noise I was telling you about.

Other factor is piston compressors will replenish the tank much quicker than the oil-less. I wish I had held out and bought the Ingersol Rand piston compressor. It was a few $ more for the same physical size, but I believe it would have been worth it. Get the largest tank that you feel you can donate space to.

Now the downside of the piston copressor. If you intend to paint, you should have larger and more effective filters. This will not be included in the basic purchase price of either compressor and will be an additional cost. Using the oil-less compressor, I was able to get by with just a water trap. Did I mention that the damn thing makes a lot of noise.

After I painted the car, I was using a DA sander with buffing pad and had the garage door open. My neighbor across the street was out doing some gardening and mentioned how he was getting tired of the noise. Something to consider in your decision making process. A friend warned me about the noise and I underestimated how loud and annoying it can be. Consider yourself warned.

Dan

If you can possibly afford it get a 2 stage compressor. They run a lot less & can handle constant on tools like die grinders much better than single stage. I would recommend a 80 gal. tank at minimum. Check for used ones as the 2 stage last a long time. My single stage 220v DeVilbiss has lasted for 5 yrs. with no problems & cost $350 at Lowes.


Mike M.

Allow me to UNrecommend a particular compressor....

I witnessed two brand new Husky oil-less compressors from Home Depot chew themselves apart, both under warranty.

After removing the cover to explore, we saw that the tiny cogged drive belt (sorta like our timing belts, but more like big rubber bands) had chewed off the teeth. Maybe something seized up, or maybe it's just el-cheapo design.

Not only is the belt permanently built into the motor-compressor assembly (nearly impossible to swap out), but the motor-compressor is a toy -- and yet the black plastic housing is a big, impressive, muscular-looking cover.

This particular model of Husky compressor is anything but husky.

--
Don Foster (near Cape Cod, MA)

I have a 3.5 electric HP with a 20 gallon tank with separate motor and compressor components. It runs most of the tools I need, including spot sandblaster, spray gun, nail guns( big and small, built addition), and small high speed grinder. It's marginal for continuous use over 65 psi at whatever CFM the spray gun uses. I like that it's portable (in basement in winter, garage in summer). Anything smaller would be pretty worthless. I avoided the unit motor/compressor setups.

I'd check the specs on your paint gun as I suspect it would be the most demanding. They generally need a pretty good volume of air at a pretty good pressure.