Garage air compressor - How big?

[livetopedal]

I'm planning ahead for my winter project -- full suspension refresh/upgrade on my 120K-mile '89 coupe. I figure this is a good excuse to invest in a compressor and tools.
My question is this: How high of a CFM (@90psi) do I really need?
Some criteria:
- will never be used for continuous high-flow applications (paint gun, grinders, etc)
-I think the highest torque I will need to generate is for removing the rear axle nuts (under 400) and they've been removed twice in the past few years so likely not completely frozen to the axle

I know its always best to get the highest CFM within your budget but do I really need 6 CFM (@90) if the highest demand on the compressor will be for working on the 911?

Thanks!

[Dmitry at Pelican Parts]

Hello Thom - I think something like the link below will suit your needs just fine. Other members will likely chime in with their personal experience and tool suggestions! Hope this helps you a bit!

10 Gallon Air Tank - PelicanParts.com

[Trackrash]

My old Craftsman compressor does the job. 2 real HP and an iron compressor. I've used it to paint my car and for my air wrench. You are going to need a real strong air wrench to undo that axle nut.

[boyt911sc]

Originally Posted by livetopedal

I'm planning ahead for my winter project -- full suspension refresh/upgrade on my 120K-mile '89 coupe. I figure this is a good excuse to invest in a compressor and tools.
My question is this: How high of a CFM (@90psi) do I really need?
Some criteria:
- will never be used for continuous high-flow applications (paint gun, grinders, etc)
-I think the highest torque I will need to generate is for removing the rear axle nuts (under 400) and they've been removed twice in the past few years so likely not completely frozen to the axle

I know its always best to get the highest CFM within your budget but do I really need 6 CFM (@90) if the highest demand on the compressor will be for working on the 911?

Thanks!

Thom,

Buying your first air compressor is a compromise and depends on your needs and many conditions. Storage, usage, and budget will dictate the size of your chosen air compressor. My first air compressor was a 20 gal./120 psi./1.5 Hp (?) if my recollection is correct. And after more than 20 years of service, the compressor was exhibiting problems and I replaced it with the same brand (Sears) but got the next bigger model at a price I was willing to spend. And got 26 gal./150 psi./2Hp and a portable air compressor for indoor projects. I thought it was more than sufficient until I hook up my sand blaster.

If you know anyone near you with a compressor, best to talk and have a look. Sears in Norristown has a nice show room with different air compressors on display. And buy it on SALE.

Tony

[Mark Salvetti]

You don't need many CFM for an impact gun, but don't discount adding more air tools later. Cutoff wheels are really handy, as are die grinders/sanders. I also use mine to fill a Jegs aluminum air tank so I have handy air for tires.

Mine does 6 cfm at 90 psi, and I wish it had more for the cutoff tool. I think you want around 6 cfm minimum. I would also go for an oil-lubed unit. They are much quieter than the oil-less units.

If my really old Craftsman were to die, I would probably go for this Harbor Freight to replace it: https://www.harborfreight.com/29-gal-2-hp-150-psi-cast-iron-vertical-air-compressor-61489.html

Next step up is about double that price.

Mark

[livetopedal]

Thanks for the replies!
I think I'll stick with the original plan for 20-25 gal. and minimum 6 CFM.
The higher price will look like a small line item in my overall suspension rebuild budget...

[steve meltzer]

I think this is really interesting and would make these comments. Reluctantly, I bought my first compressor 25 years ago...was sure i'd never use it and that it was a waste of time, space and money. It was a Sears and I used it again this AM!!...25 gal and it says 4HP, but I doubt this. It has been stellar, with only one breakdown, in it's second year, requiring a new piston. It's one of those that looks like a hot dog, oiless, as I recall. I've used it many more times than I ever would have predicted....you start lookin' for ways to use it and believe me, you'll find all kinds of times it's great to have. I found that as I did more and more stuff, tho' I never painted with it, sometimes the compressor just couldn't keep up...like grinding and using this great little hand held blaster I bought from Horrible Fright.

So, last year I bought another Craftsman compressor, on sale of course! 33 gallons and it's even better, tho' even with it, some blasting projects have a temporary stall while the device catches up. I had a small Harbor Freight jobby and it couldn't even fill tires without stopping to refill it's tank. To me, here are the salient points.

1) I'll bet the ranch, that if I check with you in 5 years, you'll be doing vastly more than you think you will.
2) Get a good one, Craftsman, Campbell Hausfeld, IR, etc. I wouldn't cheap out here.
3) I have only HF air tools, they're fine, but not their compressors, in my opinion.
4) Get the biggest one you can afford and can accommodate, you'll be glad down the road.
5) Even if you're painting, you probably don't need a 220V 2-stage compressor
6) I agree that it will take a good compressor, and maybe ?? 3/4 air ratchet to remove an axle nut. From what i've heard.
7) Always drain the tank when you're done with a project...moisture in the tank can rust out the bottom.
8) Tho' a few bucks more, I'd get that air hose that's really flexible...the stiff stuff is a pain to wrap up.
steve

[tirwin]

When I buy my next house and I have a bigger garage, shop air is a must. I will go for something like a 60 gal full upright 220V with at least 11-13 cfm. Oiled and a solid brand like Ingersoll-Rand. I have even looked at some rebuilt units (they don’t build them like they used to!). A drier is important too.

My friends who have all comprimised on the 30 gal 110V units always tell me they regret not going bigger. They all say they that once they start using it then they want to do more and they don’t have enough cfm for sustained use.

Check out the Garage Journal. Lots of good advice on there too.

[Trackrash]

I should mention that IMO a 240 volt compressor is the way to go. My compressor is dual voltage. I could wire the motor to run on 120. Yea, but it overloads the circuits if I run it on 120 v. A 240 volt compressor, even if it isn't a large one, will run much better.

[Jdub]

Big enough that it needs a 220+ outlet. Be sure you get that wired into place, then the world is your oyster.

[Reiver]

Two stage....belted....large.

[Dave Colangelo]

I have something like this mine is the lowes brand equivalent. Its always been good enough for everything I have ever done on my 911. Plenty for tires and more than enough for an impact wrench.

The skys the limit if you have the space, money and dont mind the racket...

Regards
Dave

[High Life]

Go big as you can..

Look for voltage requirements - 240v vs 120v - If you have 240v wired to your garage look for a 240V compressor - than your compressor wont work as hard and you have higher options on tank size.

Think about how big your tank is - a bigger tank means you can use air tools longer without compressor running. However the bigger the tank you then get into higher Voltage requirements.

Look for CFM ratings at 90psi - a lot of your air tools run at this pressure. The big box store brands Lowes, Kobalt, Craftsman, etc. are a bit low on CFM ratings. Ive owned a Craftsman 0 good for small jobs but was a constraint when needed to do any type of cutting, sanding, grinding with air tools...

A compressor is a good tool - so if you get the capacity to run air saws, rotary cuttoffs, sanders, polishers, etc. - You need higher CFM.. Do some research.

Also .Belt drives tend to be quieter..

Here is what I have - very happy with it thus far... Im on a limited budget and limited space and only have 120V to garage..

https://www.powerequipmentdirect.com/Chicago-Pneumatic-RCP-226VP-Air-Compressor/p2041.html

HIGHEST CFM posted thus far.. 7.1 CFM @ 90psi..

[cabmandone]

I'd start by looking at the CFM requirements of the tools you plan to use and then go a bit bigger for the compressor than the tool with the highest CFM use.

[porschenut]

Originally Posted by livetopedal

I figure this is a good excuse to invest in a compressor and tools.

It's not an investment, it's a needless expense. If you just want them, go ahead and help the economy by spending your hard-earned money

If all you need the air tools for is to get the rear axle nuts off, save yourself a lot of expense and bother and just use a 3/4" breaker bar with a pipe cheater! All the other fasteners throughout the suspension can be handled with just a breaker bar.

[Jdub]

I would agree with PNut above because he has the good sense to own an MGA, but I have to say, once you get a good compressor, you have about a million things you will use it for. It becomes indispensable.

I keep a smaller portable Craftsman for everything from blowing out irrigation lines to blowing parts free of particulate, to inflating car tires. However, I inherited a two-stage belt powered compressor that operates at 240v and it is a thing of beauty. Used it just recently to unbolt the clutch nut on an old BMW motorcycle and it was the bomb thanks to its sudden torque - all nuts and bolts fall before the amazing power of instant twist, which you will not easily get using an extension.

[steve meltzer]

I agree with Jdub....the instant torque provided by an impact tool is a thing of beauty and a joy forever! (Great for quickly removing steering wheel nuts and the nut that holds the pulley on an alternator) As noted by another poster, once you have a good compressor you won't be able to live without it. Correct: the bigger the tank, the longer you can carry on before the compressor needs to spool up again. steve

[Flat6pac]

Don’t get the oilless, they are way too noisy.
Bruce

[Goth]

I use air tools and nailers. Here is my compressor experience:

Cambell Hausfeld 4.x @ 90 w/20 gal tank. Lasted about 2 years and struggled.
Harbor freight 5 or 6 @ 90 w/10 gal tank. Did Ok but stopped working after a few months.
Husky from Home Depot 5.9 @90 w/20 gal tank. Bought it as a return item for $200 and still going strong for about 8 years now.

If you like the idea of air tools; I think 5.9 @ 90 PSI is about as low as one would want to go. Bigger tanks take longer to fill but last longer (as others have mentioned).

Hope this helps ya!

[Goth]

Originally Posted by Flat6pac

Don’t get the oilless, they are way too noisy.
Bruce

That is true. I bought oil-less with plans of paint gun use (hasn't happened yet! LOL). It must be 90+ DB's up close.