11/29/03

After several years of service, my ARB compressor started getting tired. Since it was mounted high up under the hood and often pulled duty filling up multiple sets of tires, it often overheated and blew fuses. What I needed was a high speed continuous duty compressor. What I wanted was an extremeaire compressor from www.extremeoutback.com but at nearly $400 it was really pricey.

After some searching I came across compressors from AIM Industries. One of their models looks almost identical, has the same specs and is about $200. It is a 3/4 hp continuous duty compressor that pumps out 4cfm @ 0psi. This is the Blojax DC07 or DC7000. There is also a DC5000 model. I highly recommend their install kits which include a check valve, breaker, relay and high temp hose.

Here is a side-by-side comparing the ARB compressor, on top without it's tank, and the Blowjax compressor below.

The Blowjax compressor draws about 60amps at 150psi and requires a wiring upgrade. They recommend 4 gauge but I suspect that is only if you are running over long distances. The compressor has 10 gauge leads. I used 8 gauge wire and paralleled a 30amp second relay with ARB's 40amp to give a total switching current of 70amps. I wired in an 80amp http://www.bluesea.com thermal breaker from http://www.marine.com. Yes, I know not the best idea electrically but at least the battery is protected from a short. Below are several tables on determining electrical ratings on typical thermal breakers and wiring:

I installed the compressor behind the front bumper by fabricating brackets. This is about the only place big enough and is handy for keeping it cooler than under the hood. Fortunately I do not cross deep water very often here in California.

Behind the compressor I installed a filter/water separater to keep junk out of the system. The compressor has a small filter at the inlet and I will probably replace it with something more secure for offroading. After the filter there is a check valve to keep air from back-flowing into the compressor. It is very important that a check valve be used to keep the compressor from jamming and buring out on restarts. Another very important item is using high quality hose at the compressor outlet because ordinary air hose, as shown in my picture, will quickly melt because the compressor gets pretty hot. I recommend the Load Genie combination check/unloader valve which can be purchased from Grainger under part number 5A703. This one works beautifuly and can be placed anywhere in the system; not just at the compressor head. It works better than a check valve. If your compressor doesn't flow the volume to keep the valve activated properly, you can modify/adjust the Genie valve. It is designed for up to a 6cfm compressor. Note the retaining clip on the male end. You will need to carefully remove this clip by prying up on the teeth. BUT FIRST unscrew the two halves of the valve at the center. You will note that there is a second clip inside the valve body. DO NOT remove the second clip. Removing the first clip will allow you access to the spring. Make sure to note how the pieces fit back together. Now cut coils, one at a time, until the spring can just barely return the piston to open position. Cutting less than more is better. Now reassemble and install the valve.

As seen on my ARB page, I had a pretty extensive manifold since I ran many things off the compressor. Above is my new manifold. It consists of the following. It has an air inlet on the lower left. A three way spliter output on the right to supply the pressure switch, airbag solenoid compression fitting and an isolating valve leading to the tanks. Above that are the ARB locker solenoids. The solenoids have 1/8 BSP (British Standard Pipe) threads. You will search high and low for this thread only to find someone trying to sell you adapters at an outrageous price. Skip all that and go to your local hardware store and buy a 1/8 NPT (Navy Pipe Thread) female to 1/4 NPT male. 1/8 BSP is the same as 1/8 NPT.

This picture shows the manifold installed where the ARB compressor originally was. This was a convenient place since I already had most of the wiring here. The blue lines are the ARB locker lines. The black line is the air bag supply line. The orange lines lead off to the two air tanks.

When I originally built my rock sliders I cross linked the bars so that they could be used as air tanks in the future. All that remained was to tap each one in a protected spot and run the air line to it. I installed an isolating valve so I could still run the system if the tank system develops a leak. Each slider holds 1 gallon which gives a  total of 2 gallons capacity. The compressor can fill them to 105 psi in about one minute. Two gallons is 0.25 cu ft. 105 psi is 6 atmospheres above normal.

By itself the compressor can fill a 32/10.50/16 from 15 to 35psi in about a minute. One tire holds about 3cf volume per atmosphere. Going from 15-30 is one atm. With the tanks full, the fill speed is limited mostly by the small tire stems. There's enough air to run air tools, but I don't own any.

I'm pretty happy with the AIM compressor. Though I've only had it a short time, I used it heavily on a recent trip filling multiple sets of tires. One rig had 37's and it filled them surprisingly quick. Though it doesn't have the output of a York, it will fill almost as fast when you have a couple of gallons in storage. A friend with a FJ40 has a York and a 2 gal. Another has a 4Runner with converted AC and a small tank. They feel about the same but their systems must be faster. For me, this is a huge step up from the ARB I had. I couldn't see spending twice as much for some spray paint, a sticker and the filter when this is the same unit as the xtremeair. The AIM compressor actually does have a filter. I sprayed it with some K&N oil for the moment but in the future I might do something different. You can buy a better filter setup from AIM too. They also sell many other accessories like the check valve and an oiler. You need to figure more than just the cost of the compressor. Though the compressor is oil-less I recommend spraying some compressor oil into the intake intermittantly every 20 hours of use. Harbor Freight sells a 120V version of this compressor for like $97.

Update 9/05: I'm still very happy with compressor. It has been very reliable and served me well. I even used it for hours (intermittantly) running a nail gun to install insulation in my attic. The only change made to the system was swapping the check valve for the Genie unloader as described above.

http://www.larsdennert.com