Air Compressor Question

[Matthan]

I have a 6.1 HP,150 PSI Max, 28 Gallon Air Compressor is this good enough to use to paint a car?

[carolina charger]

 Sure is.

[oldrock]

you can paint a car with way less than that setup. You should be in great shape with that rig.

[Silver R/T]

you can paint a car with way less than that setup. You should be in great shape with that rig.

you can paint car without compressor at all! but is it recommended? Your compressor will be running continuously, you will have to stop after a bit to let it pump up. 6.1HP thats PEAK hp rating, right? Running hp is probably half that. Depends on spray gun you use, but most new HVLP guns require no more than 10PSI at the cap.

[Matthan]

Thanks for the info just wanted to make sure

[elitecustombody]

as silver mentionned,it will be running non-stop and most likely will not be able to keep up,unless you will be painting the car piece by piece

[375instroke]

I can't stand the HP rating of electric motors.  You'll notice that the data plates on air compressors is often blank, because the compressor manufactures like to lie about the HP rating.  If you have a maxed out circuit, that is 20 amps at 115 volts, that gives you 2300 watts.  This equals 3 horsepower.  A 15 amp circuit maxes out at 1725 watts, or 2.3 horsepower.  So, all the HP ratings are useless.  They often tell you how much CFM at a given pressure, and that's what you need to know.  My SATAjet uses 15.2CFM at 29psi.  The newer compressors are often rated at a running rating, which is more realistic.  The numbers are like 1.6 or 1.8HP instead of the previous 5HP, 20 gallon standard used previously.  There was a class action law suit, and the penalty was that the compressor manufacturers has to give people a $20 off coupon to buy a new compressor.  What a deal.  A Craftsman 20gal, 1.6HP compressor is rated at 7.6CFM at 40psi, so it's totally inadequate.  Their 60gal, 3.2HP, 220volt compressor gives 12.4CFM at 40psi, so it may be enough at 29psi, and it's $600.  Next step up is the $950, 80gal, 5.4HP unit, but it is rated at 13.3CFM at 100psi, not 40psi.

[FJMG]

You hit it bang-on 375instroke and I will add that most circuit breakers are designed to be loaded at approx 80% which woould mean that you really cannot rely on anything more than about 1.6 or 1.7 hp on 110 volts!

[Chatt69chgr]

Getting the moisture out of the compressed air is singularly important when painting.  The little rinky dink dryers that screw onto the compressor tank are really not adequate---unless you live in Arizona, New Mexico, or Nevada where relative humidity is very low.  In any case, you need an inline dryer right before the gun.  One way to get the moisture out is run the air through 20 ft of black iron pipe.  A schematic for this setup is on the TP Tools website.  They sell good sandblasting tools and dry air is important for that too.  The other way is to use a refrigerated dryer.  Harbor Freight had one on their online store.  Never saw it in the local store.  Was maybe $300.  I actually did paint the right front fender of my old 73 Ford pickup with a Sears 20 gal outfit in the driveway.  Was spraying acrylic enamel and used a Sears spraygun.  Incredibly, it worked and lasted until I got rid of the truck 25 years later.  But I don't think I would try this with the new basecoat/clearcoat systems.  Plus, the stuff in those paints will kill you if you breath it.  You need a fresh air supply, full face mask, and paint suit to keep the stuff out of your lungs and off exposed skin. 

[Matthan]

I only asked if was good enough to paint a car.

[Troy]

I would say "no" (or at least "probably not") but I'm not an expert. I believe that the compressor will run non-stop which will heat the air and introduce condensation. I think the ideal goal is more volume (ie 2 large tanks) so the motor doesn't run all the time. There are dryers and other helpful tips (like the black pipe) to help of course. Some can get expensive for a one-time DIY job. I suppose it also depends on your spray equipment. What are the requirements for your paint gun?

I believe in overkill so I could very well be wrong here. I have found that I use my compressor a lot more for grinding, sanding, and cleaning so it actually gets a break when spraying.

Troy

[Mike DC]

They often tell you how much CFM at a given pressure, and that's what you need to know.

Yes, yes, yes. 

[Supercharged Riot]

Im looking for an air compressor as well. 

My application requires just enough efficiency to run air tools so that I can overhaul my engine & transmission etc.

What are the minimum specs I should look out for?

[Rolling_Thunder]

I am in the market as well for a compressor...   looking at an 80 gallon stand up one -    might be using it to paint a car so - we shall see.

[oldrock]

Im looking for an air compressor as well. 

My application requires just enough efficiency to run air tools so that I can overhaul my engine & transmission etc.

What are the minimum specs I should look out for?

for air tools, largest you can afford is usually the answer. Some air tools can be real hogs when it comes to air needs. I have a small compressor and some of my high demand air tools are a pain to use. I get maybe 30seconds of use and then have to pause for the stupid air compressor to catch back up. Some air tools take alot more air than others though so comes down to what you are driving. My air rachets don't use much air so no problem. My angle grinder on the other hand is an air hog!

[375instroke]

Im looking for an air compressor as well. 

My application requires just enough efficiency to run air tools so that I can overhaul my engine & transmission etc.

What are the minimum specs I should look out for?

I am in the market as well for a compressor...   looking at an 80 gallon stand up one -    might be using it to paint a car so - we shall see.

I explained it earlier, but here's a recap:  A big tank only helps if you are using a lot of air for a short amount of time.  If you are doing something like porting heads or sandblasting, you need a big motor and pump.  A big tank won't make up for a small pump.  If the pump will keep up, a larger tank will prevent the pump from turning on and off for short periods of time constantly.  If the pump is too small, it will just keep on pumping, you won't have enough pressure, and you will be spitting out a lot of water.  Ignore HP and concentrate on CFM.  Also pay attention to the pressure that CFM is rated at.  The higher the pressure, the more air that cubic foot contains.  One cubic foot of air at 90psi contains 7 standard cubic feet of air.  The specific tool you want to use will have an air requirement rating on the box or on the web site.  It'll say ???CFM@???PSI.  Air tools, like an impact wrench, or die grinder, want 90 to 120psi.  An HVLP paint gun may want something like 30psi.  A compressor can pump more air volume at 30psi than it can at 120psi.  It doesn't have to compress as much air to get to that lower pressure.  Compressors will also give an output of ???CFM@???PSI, so just get a compressor with more air flow, at the pressure that is required, than what the tools you will be using require.  Some terms used are SCFM, or standard cubic feet per minute, and ACFM, or actual cubic feet per minute.  We probably don't care about the specifics of these.  We just want to know if we'll get the air we need out of the compressor.  I talked about bogus HP numbers earlier.  A very common size home compressor, a 5HP/20gal. 115v unit usually costs around $300 under the old system of bullshit.  You'd get about 4.9SCFM@90psi, and 6.3SCFM@40psi.  A Snap-On 5HP compressor outputs 14SCFM@175psi.  It also costs $2400.

[SG1022]

Im looking for an air compressor as well. 

My application requires just enough efficiency to run air tools so that I can overhaul my engine & transmission etc.

What are the minimum specs I should look out for?

for air tools, largest you can afford is usually the answer. Some air tools can be real hogs when it comes to air needs. I have a small compressor and some of my high demand air tools are a pain to use. I get maybe 30seconds of use and then have to pause for the stupid air compressor to catch back up. Some air tools take alot more air than others though so comes down to what you are driving. My air rachets don't use much air so no problem. My angle grinder on the other hand is an air hog!

I agree, that's just no good. As far as I am concerned pausing for 30 seconds is not a usable tool.

[AmadeusCharger500]

I've been using the pause every 30 second air comressor for 7 years. Its become quite the Pita. Maybe Im gettin old and lesss patient ( wait is the reverse?) Anyway I have been shopping for a compressor for the past year and amidst all the confusing not standards they like to spout I have also come to think its all about cfm rating. So I went and purchased a 3.5 Hp 240v that will do 12.5@ 90 14.5@40. I have yet to do any real work as its been bitch weather but Im thinking this will be a great improvemt and I will be able to paint if needed. BTW I did paint my 71 with the old compressor (twice). You just need a great deal of patience and fresh air system.

[375instroke]

How much?  I guess I'll relegate my oilless compressor to supplying breathing air, and something like yours for everything else.  My SATAjet uses 15.2CFM at 29psi, so that looks like it would be marginal for me.  Sears has a 60gal, 3.2HP, 220volt compressor that gives 12.4CFM at 40psi, so it may be enough at 29psi, and it's $600.  What brands should people stay away from?

[Troy]

I have one of these (vertical):
http://www.eatoncompressor.com/catalog/item/504747/172993.htm

One of the best tools I own so far. I got it on sale for less than $1,100 and I picked it up in person.

Troy

[AmadeusCharger500]

I am not sure what to stay away from.I purhased mine from compressorsdirect. IT was a chicago compressor and was the only one to which I could find a good online review. They offer a liftage service off $100 and the shipping is otherwise free. Very helpful since these weigh about 250lbs.
Total cost was $850.