On-Board Air Compressor

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After seeing the benefits of airing-down for off-roading (and its requisite airing-up to return home), the need for on-board air became apparent. While many of the developed off-road parks have air stations, some don't and most of the undeveloped locations are in remote areas. I had used a plug-into-the-lighter compressor in the past on my Land Cruiser, but found filling big tires to high pressures took f-o-r-e-v-e-r. Also, I could just see one of those things do the meltdown bit after filling 2 or 3 big meats. I have a big 12 CFM air compressor in my garage and a big collection of air tools. So, I felt it wise to get a source of on-board air that was useful for more than just filling tires.

I looked around and found several sources of compressors. There were several in the $100-200 range that were under 1 CFM, that would be adequate for tire inflation, but lacked the oomph for air tools. I looked at modified A/C compressors, but was unwilling to give up my currently functioning A/C and also had no room for adding anything else to the cramped engine compartment (A/C, alternator, power steering, etc.). So then I stumbled on a few compressors in the $500 range, all but one was too big to fit in the engine compartment. The Currie unit, at 12" long was about as big as I could handle. It has a optional ~1/2 gallon tank, pressure switch, solenoid, and gauge. It is intended for continuous, unattended use and is oil-less. It actually consists of a Thomas motor/compressor assembly. I've heard Thomas manufactures a high quality unit.


Here's what my installation looks like:

1. front view of compressor

2. mounting studs

3. side view of compressor 4. air tank

  1. Pictured (clockwise from the bottom) are the compressor, its solenoid (behind the fuse box), the air pressure gauge, the toggle switch (attached to the evaporative recovery canister) and my relocated differential breather air filter on the firewall.
  2. Shown are the mounting studs that attach to the wheel well. I used sections of 1/2" galvanized pipe angle-cut to fit the wheel well slope through which bolts extend up from beneath the wheel well to secure the compressor. I used my old rubber sway bar endlink bushings under the compressor to isolate vibration and allow some leveling.
  3. Observe the low profile of the unit. It is tucked safely out of harms way. A quick disconnect chuck is attached to the sheet metal in front of the windshield washer tank (upper left hand corner of the picture). I used a plastic cover to keep dirt out of the chuck when not in use. I carry a self-coiling 1/4" plastic hose for attaching to the front connection. I may fabricate a sort of tray to mount between the edge of the hood opening and the compressor motor. This will cover up some of the exposed power connections and also serve as a handy tool and small parts tray when working on the engine.
  4. Air tank mounting between the frame rail and transfer case on the passenger side. The tank is 5" dia. x 14" long, or about 1.2 gallon capacity. I ran 1/4" air line from the compressor (quick disconnect chuck) down to the tank and a return line back to the front of the hood.

I also added a quick-disconnect chuck to my Quadra-Flate tire inflator. As shipped I find this unit to requires three hands to operate, as you need to hold the central valve/gauge assembly in one, hold the air chuck to it with another and then operate the manual valve with a third hand to check the tire pressure periodically. This way, I can just chuck it in and go.

I tested airing up all 4 33 x 9.50 BFG M/Ts and with an empty tank and engine off, I can fill them from 12 to 32 PSI in 7 minutes. With engine on and tank full, its about 6. On the other hand, filling 4 33x15.50 Super Swamper TSL/SXs from 10 to 30 PSI takes about 18 minutes.

After a year of use, I've had no problems with the unit. I am planning on modifying the air system a bit. If my front bumper holds air, I'll be plumbing it for use as an air tank. I'll be relocating the current air tank to free up the space for an auxiliary battery. I also want to reduce the amount of air hose in the system for better flow rates, right now, 1/4" hose runs from the compressor to the tank then out of the tank back to the outlet located near the compressor.


  Compressor         $495
  Air Tank             75
  Mounting hardware    20
  Air hose/chucks/etc. 30
  Misc. electrical     10
  Total              $630


  bananabanana and a few $$$ (but well worth it!)


I just got done plumbing my front bumper for air and it holds air, woo hoo! I get about 1 gallon on each side. I drilled 7/16" holes on the bottom side of the 3x5" tubing, tapped for 1/4" NPT and screwed in some right angle brass hose fittings. I plan on running the air hose to the back and doing a similar conversion on the back bumper for an extra 3 gallons of air.

Other Air Sources:

A number of other sources of on-board air are available. Of the non-engine driven sources, I've compiled a list of air up times (35x12.50 tire measured in seconds) to use as comparison:

Begin/End (psi) Currie QuickAir-II ARB PowerTank
8 / 30 230 260 355 115
8 / 25 175 180 265 85
8 / 15 65 70 95 30
15 / 25 110 110 170 55
25 / 30 55 75 90 20
Approx. Cost ($) 495 255 25 299
Run Time Unlimited 40 minutes 40 minutes 40 32" tires, 15-30 psi

This data was measured without any air storage tank, except the PowerTank, which is nothing but an air (actually CO2) tank and the ARB which includes a small internal tank.

The modified air conditioning compressor is also a popular air source:

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Last updated: 16.JUN.1999