Onboard Air Research

[tdesanto]

So, I’m trying to weigh my options for an onboard air system. Cost/size/speed/functionality are all something to consider. I’ll be using this mainly to air up my tires and firestone airbags (once installed), but may decide later to run an impact wrench or a few air tools.

Also, I have a few basic questions at the outset as I’m trying to figure out where I might even install a compressor and possibly a tank. Outside the cabin, space is tight. Engine bay is not really even an option, at least I haven’t been able to find a solution to shoehorn anything bigger than a relay or two in there.

1. Can I install a compressor under the body of my truck and have it exposed to all the elements? If I do this, what about the air intake and air filter?

2. If I choose to mount the compressor inside the cabin, just how loud will one of these be?

3. 33% duty cycle vs. 100% duty cycle. Some of these compressors trade CFM for duty cycle. If I’m only using it to air up tires, and maybe connect to a 2 gallon air tank to run the occasional air tool, then could I get away with a 33% duty cycle compressor and gain the higher volume they offer?

I’m trying to decide between the following compressor setups:

1. ExtremeAire Severe Duty—the ¾ horsepower 4CFM model for about $400. This seems to offer the durability of a 100% duty cycle compressor with the volume greater than any of the other 33% duty cycle compressors I’ve looked at. But, it does so at a higher cost/ bigger size/ higher amp draw.
2. Viar 450C with a 1 or 2 gallon air tank (assuming I can find a spot to mount the tank). Only 1.66 CFM, but I was hoping that once the air tank is full then it would be able to keep up with my needs per my application.
3. Viar 400H/400C tank optional (33% duty cycle, 2.54cfm). If I can get away with using only a 33% duty cycle device here, maybe even connect it to a tank, this seemed like it would run faster for me. Can a 33% duty cycle compressor be used with a tank?

So, I’d be grateful for anyone who could help me with some of these questions and concerns.

Many thanks,

Tony

 

[Nullifier]

WEll first of all You can mount the Air compresor to the chassis that is not a foul. Just do not turn it on in deep water and check the filter periodically.

If you are in a water area then run the intake extension on the copressor to higher ground and you will be fine.

For duty cycle you will be good with a 33% cycle. They usually off better cfm stats but I would not run the tank. Just go for a multi port to accomodate quick chucks, lockers etc.

Personally I run the Viair 460c unit which is usually marketed to the street crowd. I run the viar 2.5 tank and am really happy with it. THere are other comps that are faster but I am not in a hurry that often. If I was going to try to run a larger output system I would go with 2 460 units for about the same as a large single comp. This would give me a back up if I had a problem and give me comparable cfm stats.

 

[theMec]

I haven't gotten down to comparing specs but I've been thinking about the Warn winch/compressor combo (PowerPlant Dual Force HP or HD)
http://www.warn.com/powerplant.shtml
It comes w/ a 1/2 gallon air tank so I don't know that you'd need to have a larger one.

 

[slooowr6]

Take a loot at this thread, http://www.wanderthewest.com/forum/showthread.php?t=966 He made a very nice on board Air setup. He has Firestone Ride-Rite bag as well but it's not connect to the air tank.

It should answer some of your questions.

 

[tdesanto]

Thanks, gentlemen, for all the quick replies. I will follow up on the links that you sent. Thanks, too, for the clarification on the 33% duty cycle compressors and extending the air intake to a safe location.

Doing further research revealed filter fittings for the Viair compressors to relocate the air intake filter: http://www.viaircorp.com/assemblies.html

 

[ujoint]

Check out Warn's new line of compressors. I got the VTC for it's power & size. I'll be mounting it to a skidplate where my spare tire used to live. They have 3 models of the new compressors. I'll then plumb it to the front & rear using components from Kilby Ent.

http://www.warn.com/truck/air-compressors.shtml

 

[BigAl]

I haven't gotten down to comparing specs but I've been thinking about the Warn winch/compressor combo (PowerPlant Dual Force HP or HD)
http://www.warn.com/powerplant.shtml
It comes w/ a 1/2 gallon air tank so I don't know that you'd need to have a larger one.

I've had the HP for ~6 months now, I love it. No hassle, no plumbing to run. Without an auxillary tank it takes my 36" tires from 8 to 25psi in ~2 minutes each. I use it every time I go out

 

[texas taco]

I was given a Thomas compressor which I think is about 1.5 cfm "I think" I have a 5 gallon tank under my bed. With only 1oo PSI in the tank i can use an impact to change a tire if i dont get crazy with it. It airs up tires good to. I plan on putting a 150 psi pressure switch, and regulate it down to about 80 psi. which should make it much better. If you dont have a compressor that can really maintain you can cheat with a tank. I have used my system many times, which includes using an impact and I am very happy with it. A Few tweaks and it will be almost perfect..

 

[madizell]

My personal experience with on-board air is that having a tank in the system does not compensate for cfm output from the pump. The tank will draw down quickly, and you will be left with whatever the pump can produce. This is assuming that any tank used will be rather small, i.e., 2 gallons or less. Whether airing up tires or attempting to run tools, a tank of 2 gallons won't make much difference in performance if the compressor won't otherwise do the job. My 1.5 gallon tank draws down to compressor line pressure in less than 10 seconds.

Most air tools use 4 cfm or more at 40 to 90 pounds. Few portable pumps can drive such tools at all, and even with a tank in line, most will run the tool for only a few seconds. If you are serious about using tools on the trail, go for the larger compressor with a 100% duty cycle, and yes, they are loud. I have experienced the extreme duty unit you mention, and you won't want to be inside the vehicle while the pump is running. At least, I found it to be obnoxiously load.

As for mounting the compressor under the vehicle exposed to the elements, I don't think it is a good idea, but if it is your only option, you could give it a try.

 

[tdesanto]

My personal experience with on-board air is that having a tank in the system does not compensate for cfm output from the pump. The tank will draw down quickly, and you will be left with whatever the pump can produce. This is assuming that any tank used will be rather small, i.e., 2 gallons or less. Whether airing up tires or attempting to run tools, a tank of 2 gallons won't make much difference in performance if the compressor won't otherwise do the job. My 1.5 gallon tank draws down to compressor line pressure in less than 10 seconds.

Most air tools use 4 cfm or more at 40 to 90 pounds. Few portable pumps can drive such tools at all, and even with a tank in line, most will run the tool for only a few seconds. If you are serious about using tools on the trail, go for the larger compressor with a 100% duty cycle, and yes, they are loud. I have experienced the extreme duty unit you mention, and you won't want to be inside the vehicle while the pump is running. At least, I found it to be obnoxiously load.

As for mounting the compressor under the vehicle exposed to the elements, I don't think it is a good idea, but if it is your only option, you could give it a try.

Greg, thanks for the help. I was looking for that kind of feedback on the added or lack of added assistance that a small tank would provide. It would be great if the compressor manufacturers provided a db rating on the noise level that they produce.

I really liked your A/C compressor converted to on-board-air; however, I don't think I could give up my A/C living in TX. :drool:

 

[ujoint]

Here's a link to a video featuring a really cool guy demonstrating OBA on 2 Jeeps.....

http://www.youtube.com/watch?v=HSuQrnsVLmw

 

[madizell]

Actually, I found the Kilby video to be very instructive, and it tends to demonstrate what I was saying about tanks and output. Early in the video, you get a glimpse of the tank under the vehicle, which looks to me like a low profile 2 to 3 gallon tank, which would have up to twice the reserve capacity of my humble 1.5 g tank. The Kilby unit, as I recall, is a modified York a/c compressor, which has been the standard for off-road systems for a long time due to the capacity of the York to produce both volume and pressure, as well as having a lubricated lower end for long life. The Extreme Outback system uses either a similar pump or an identical one.

In the several demonstrations in the video, the tank drained down and the pump cycled within 5 to 10 seconds while airing tires, and in less than 5 seconds using the air nozzle (one of the highest consumers of cfm.) With the impact wrench, the pump cycled almost immediately, but the video clip only shows a few seconds of removing lug nuts (the big consumer of air), then shifts to showing zipping on the nuts, which uses far less air. Not clearly shown is the system's ability to sustain the load of removing 5 lug nuts. I suspect that it works, but that the wrench does not remove nuts as readily on line pressure alone as it does on full tank pressure. This stands to reason due to the drop in pressure as between the full tank pressure and sustainable line pressure, and may be the reason the video was edited as it was.

IMHO, Kilby makes as fine a product as you can buy. One of the benefits of such a system, if you have room under the hood for it, is that it runs off the engine, not off of 12 volts. The 12 volt systems, such as the Extreme Outback system, use an electric motor that is either a starter motor or winch motor (I don't know which). Amperage draw at full strain will be high. Starter motors can draw 125 amps easily, and winches draw up to 450 amps. Read the manufacturers literature carefully to determine the electrical needs if you go with a 12 volt system.

One OBA pump I would not use for airing tires is the ARB mini pump sold as an air source for lockers. They are a light duty cycle device and are not intended for the duty cycle needed to air tires, in spite of the fact that ARB sells a tire air-up kit for the pump. I have melted two fuses using the ARB pump for airing tires, one of those times being at the end of a long trail ride with the ARB rep for the west coast. When I fried the fuse, he said that the system "was never intended for airing tires, and ARB only sold the hose system because folks asked for it."

Presumably, the new Warn combo units use the winch motor to drive an air pump, and I would expect that the air compressor would cause the electric motor to draw about as much amperage as the winch would use under medium loads. Airing tires, however, would cause such an electrical draw on the system far longer than your standard winch recovery if you are airing up 4 tires (or 8 if your buddy does not have OBA.) In the case of either a full capacity 12 volt device like the Extreme Outback, or the new Warn units, expect to provide winch-grade wiring and a high capacity alternator to put such units to their best use.

 

[madizell]

I really liked your A/C compressor converted to on-board-air; however, I don't think I could give up my A/C living in TX. :drool:

In Alaska it was not an issue. Racing in Australia, I didn't have time to worry about the heat. Haven't been here in Arizona long enough yet to have an opinion, but my F-150 does not have AC, and so far it has not been too big a deal. Still, the weather in Prescott is mild compared to Phoenix and a lot of other places, including much of Texas. I would not suggest bypassing your factory air on a daily driver just to get OBA. Instead, see if it is possible to fit something like the Kilby system under your hood. If not, well, I would still go for as much capacity as I could afford in whatever system you choose.

 

[ujoint]

Glad you enjoyed the video. The editor cut the lug removing short, don't really know why. They did all come off at about the same speed, the difference really not noticable. That was demonstrated on the JK, which idles really low, performance would be even better with some more RPM. I made the video to act as a simple tool to demonstrate the speed of the system, and it's done good so far. I think it's better to see something instead of just reading the specs!!! I have plans for more videos in the future!! ---Chris

p.s--the tank shown on both rigs is our 2.5 gallon

 

[tdesanto]

ExtremeAire

Well, I finally decided on the ExtremAire with their 4 gallon tank. Over the last week I've had to call George at Extreme Outback a few times and even sent him a few drawings of a custom enclosure I'm building to hold it all.

He took the time to answer my email and both my phone calls. I must say that he is one of the most helpful guys I've met and is very knowledgeable.

I really enjoy buying products from folks like him. Solid products and solid customer service. What a great combination.

Can't wait to get the install done and start using it. I'll probably air down just so I can air back up :elkgrin: .