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Onboard Air - What do I actually need?

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I've avoided designing my onboard air system until now, but am having second thoughts about waiting until the interior is more built out. Seems like running wires and air lines might be easier now than when the walls and cabinets are in. My goals are:

-Remotely control the airbags (up or down) from the dash to be able to level the van at campsites, get extra lift when going offroad, maintain airbag pressure for road/load conditions)
-Refill the van tires after airing down for off-road (30/45 PSI to 55/75PSI)
-Blow out dust and sand from the van interior, dry the dog, quick dry things

-Idea is to have a central tank (2.5 - 5 gallons) under the chassis in the rear in front of my spare tire (tons of room on my extended).

-I'll run some quick connect air fittings from the tank to both sides of the van and possibly the rear bumper, and one inside, in order to be able to fill up the van tires, bike tires, and inflatables (tubes, air mattresses, etc).

-I'll have Airlift 5000 Ultimate bags in the rear. Planning on having a manual control for them up in the dash using this: https://www.amazon.com/gp/product/B001F12LZA/ref=ox_sc_saved_title_8?smid=ATVPDKIKX0DER&psc=1

-The air manifold will just hook in to the bags and tank (with pressure regulator).

-Tank will have a pressure switch to turn the compressor on when it gets below a certain value. I'll probably try to wire up an air pressure gauge to the tank itself that is a sending unit to my Victron Cerbo GX so I can check tank pressures. Finally, I'll have an on/off switch for the compressor, either in the dash or in the back, to cut power to the compressors (I won't keep it on or the tanks full most of the time.)

The one piece of the puzzle I'm still trying to figure out is what compressor setup to run. I don't really want the compressor inside the van.
I pretty much want 100% duty cycle.

ARB Twin Compressor (CKMTA12): $600, 4.68 CFM @30PSI, 150 PSI Max, 70A current draw. Only IP55 rated, which is the main problem. I don't really think it's a good idea to mount it under the van. I could try to create a mostly water/splashproof box and use an air intake relocate kit into the interior of the van, but that's a decent amount of effort. I was thinking about trying to mount it in front of the driver side wheel in the bumper (same spot as the windshield fluid reservoir, just opposite side. Should be pretty protected and have good air with the front wheel liners installed. Problem with that is running the power wires for 70A over to CCP2 inside the cab - needs pretty thick wires and that space is already too crowded with my audio install. Running super thick gauge wire to the back passenger side of the van where my house electrical is seems a non-starter.

Viair 485C Compressor: $400, 1.67 CFM @30PSI, 1.36 CFM @80PSI. .
200 PSI Max, 23A current draw, IP67 Rated, 100% Duty cycle at 200 PSI.
Could mount this under the chassis no problem, wiring would be pretty easy and straightforward. But the fill rate seems low? Says 5.25 min to go from 0-30 PSI on a 37" tire, 1.5 min to go from 15-30 PSI. No clue what that means from going from 45-75PSI, but I'd assume it would take slower (6 min a tire?)

Viair 485C Dual Compressors: $525, 3.05 CFM @30PSI, 2.34 CFM @80PSI.
200 PSI Max, 44A current draw, IP67 Rated, 100% Duty cycle at 200 PSI.
Enough space under the chassis as well. Says 3.75 min to go from 0-30 PSI on a 37" tire, 1.8 min to go from 15-30 PSI.


Anyways, just trying to figure out what I actually need. Seems like most people have compressors considerably less powerful than these (like Viair 88P, 1.25 CFM at 30PSI, .75 CFM at 80PSI, only 25min Duty cycle at 30 PSI)? Seems like this is not nearly adequate to get the van from air-down pressures back up to Highway pressures? Am I missing something?
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2021 T350 Cargo HR 148 AWD
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I'll be planning a similar setup soon. I went with the Napa brand air compressor. Lots of positive youtube reviews that compare this less expensive compressor to the ARB. Some videos show it out performing the ARB.


I'm trying to fit my compressor in the drivers side wheel well electrical box but I am running out of room very quickly on my non extended. I'm going for a simpler setup: one air chuck in the rear, no air tank and on/off switch near the air chuck.

For your desired setup, it would be easy to add driver/pass air chucks at any time, just get some push lock fittings for the compressor.
 

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2022 W2X 350 HR AWD EB
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I’ve been running the ARB twin compressor for several years on my Jeep. It’s mounted under the hood and I’ve not had a problem with it getting wet. I have a friend that mounted one under his van and has had to replace one of the compressors twice. He doesn’t use the remote air intakes which could be the problem.

The 70 amps is for both motors so you only need to run 35 amps per wire. The ARB wiring harness is fused a 2x40 amps.

I’ll be installing an ARB on my Van when I get it. I can fill my 37” tires from 10psi to 33psi quickly. I’ve not timed how long it takes per tire but if I’m with others I’ll often be done before they get two of their tires filled. If we’re in a hurry I’ll go fill their other two tires to speed the process.
 

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Discussion Starter · #4 ·
I called Viair, the guy I talked to said that going from 0-30 PSI (or 15-45 PSI) should take a lot longer than going from 30 PSI to 60 PSI (or 45-75PSI). And our tires have a lot less volume than jeep tires, So he recommended just the single 485C.

I think that makes sense to me, so I’ll probably go with the single 485C compressor. A guy on the Facebook group said his 300P compressor can air his tires back up in a couple minutes (1.6cfm @30psi, 1cf @80psi). If I have a 4-5 gallon tank at 200psi to start, that should help too.
 

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I called Viair, the guy I talked to said that going from 0-30 PSI (or 15-45 PSI) should take a lot longer than going from 30 PSI to 60 PSI (or 45-75PSI). And our tires have a lot less volume than jeep tires, So he recommended just the single 485C.

I think that makes sense to me, so I’ll probably go with the single 485C compressor. A guy on the Facebook group said his 300P compressor can air his tires back up in a couple minutes (1.6cfm @30psi, 1cf @80psi). If I have a 4-5 gallon tank at 200psi to start, that should help too.
I started with a Viair 400. The compressors are easy to switch out if you find it’s not working for you.
 

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Discussion Starter · #8 ·
I have a single 480C and moving to the dual 285s. But then again, these are critical for my build (and safety). 2 is one and all...

On the 480C though, from 20->65-75 PSI is about 7-8 mins per tire.
You’re moving to dual 485c compressors you mean? And hmm the 485c is only 10% stronger than the 480c so that wouldn’t bode well for me. Maybe 4-5min based off that to go from 30->55 psi front and 45->75 psi rear.
 

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I've avoided designing my onboard air system until now, but am having second thoughts about waiting until the interior is more built out. Seems like running wires and air lines might be easier now than when the walls and cabinets are in. My goals are:

-Remotely control the airbags (up or down) from the dash to be able to level the van at campsites, get extra lift when going offroad, maintain airbag pressure for road/load conditions)
-Refill the van tires after airing down for off-road (30/45 PSI to 55/75PSI)
-Blow out dust and sand from the van interior, dry the dog, quick dry things

-Idea is to have a central tank (2.5 - 5 gallons) under the chassis in the rear in front of my spare tire (tons of room on my extended).

-I'll run some quick connect air fittings from the tank to both sides of the van and possibly the rear bumper, and one inside, in order to be able to fill up the van tires, bike tires, and inflatables (tubes, air mattresses, etc).

-I'll have Airlift 5000 Ultimate bags in the rear. Planning on having a manual control for them up in the dash using this: https://www.amazon.com/gp/product/B001F12LZA/ref=ox_sc_saved_title_8?smid=ATVPDKIKX0DER&psc=1

-The air manifold will just hook in to the bags and tank (with pressure regulator).

-Tank will have a pressure switch to turn the compressor on when it gets below a certain value. I'll probably try to wire up an air pressure gauge to the tank itself that is a sending unit to my Victron Cerbo GX so I can check tank pressures. Finally, I'll have an on/off switch for the compressor, either in the dash or in the back, to cut power to the compressors (I won't keep it on or the tanks full most of the time.)

The one piece of the puzzle I'm still trying to figure out is what compressor setup to run. I don't really want the compressor inside the van.
I pretty much want 100% duty cycle.

ARB Twin Compressor (CKMTA12): $600, 4.68 CFM @30PSI, 150 PSI Max, 70A current draw. Only IP55 rated, which is the main problem. I don't really think it's a good idea to mount it under the van. I could try to create a mostly water/splashproof box and use an air intake relocate kit into the interior of the van, but that's a decent amount of effort. I was thinking about trying to mount it in front of the driver side wheel in the bumper (same spot as the windshield fluid reservoir, just opposite side. Should be pretty protected and have good air with the front wheel liners installed. Problem with that is running the power wires for 70A over to CCP2 inside the cab - needs pretty thick wires and that space is already too crowded with my audio install. Running super thick gauge wire to the back passenger side of the van where my house electrical is seems a non-starter.

Viair 485C Compressor: $400, 1.67 CFM @30PSI, 1.36 CFM @80PSI. .
200 PSI Max, 23A current draw, IP67 Rated, 100% Duty cycle at 200 PSI.
Could mount this under the chassis no problem, wiring would be pretty easy and straightforward. But the fill rate seems low? Says 5.25 min to go from 0-30 PSI on a 37" tire, 1.5 min to go from 15-30 PSI. No clue what that means from going from 45-75PSI, but I'd assume it would take slower (6 min a tire?)

Viair 485C Dual Compressors: $525, 3.05 CFM @30PSI, 2.34 CFM @80PSI.
200 PSI Max, 44A current draw, IP67 Rated, 100% Duty cycle at 200 PSI.
Enough space under the chassis as well. Says 3.75 min to go from 0-30 PSI on a 37" tire, 1.8 min to go from 15-30 PSI.


Anyways, just trying to figure out what I actually need. Seems like most people have compressors considerably less powerful than these (like Viair 88P, 1.25 CFM at 30PSI, .75 CFM at 80PSI, only 25min Duty cycle at 30 PSI)? Seems like this is not nearly adequate to get the van from air-down pressures back up to Highway pressures? Am I missing something?
I've been very happy with the Viair 400P, which is popular with off roaders for good reason. I got the automatic version and I'm glad I did. Was like $220 new on an ebay competitor site. I thought about mounting it underneath but it's too dirty down there, so I usually just pack it. It's very easy to setup; 1-2 minutes tops, and always clean as a whistle inside it's carry case. I rigged up a fused always hot connection to CCP2 that sits right there by the open driver's door. I use it often. More about that here.

But so far I don't have air bag plans, or really need compressed air for anything. The factory rake plus the VC lift kit (no bilsteins up front) have made it so that even with most of my big ticket heavy items installed the rear is still higher than the front, so rear airbags would only make it worse (that annoying ~80mph drone sound is gone though). I typically park with the front facing uphill to help overcome this. When on level ground or if I can't face uphill, I can press just the head lift button on my adjustable bed remote for a second. But that only buys about 1-2" before it starts to feel awkward at the hip/chest area while sleeping, and I have to remember to do it every night. A little side to side tilt isn't a huge deal because the bed faces front to back, but I guess it would be nice to be perfectly level on that axis. I just can't tell if air bags and all the gear to make them work are worth the effort. Here's a shot of the adjustable before I put the mattress on. I friggin love this thing. Have used one at home for decades.
Couch Furniture Comfort Wood studio couch

For people with side to side beds, I could see air bags being more useful, but again, with a VC lift and no Bilstein's, you might have a rake even after your build is complete, so airing up either rear bag would make it worse, which might cause you to roll out of your bed, or be at a diagonal. You can build your bed platform to lean towards the back, but it would need to over-lean beyond level and then you'd need to air up both bags by some amount every time, otherwise just using one bag would again create a diagonal or forward lean/roll.

I've read a few people on the forum say they won't drive with the bags inflated anymore. Not sure what that's all about, but might be worth looking into.

Anyhow with the 400P Automatic I have no problems airing down and back up without interruption even on hot days. The automatic stops itself between tire fills, and I usually only drop 5-10 PSI even for thick sand and gnarly death valley jeep trails and just skip filling back up on the way out. If you air down too far, you start giving up ground clearance, which is a bigger issue on most of the rough roads I take, even with 265/75/16's.

The factory PSI ratings on the van are also very high because they have to cover even heavily loaded rigs, and while my build has a massive power system, it's still not heavy enough that 5 PSI matters, yet that's usually all it takes to trim the edge off of the ride harshness and improve traction a bit. I've been through insanely thick sand like that without any issues. Just gotta keep a bit of momentum. You can go much slower if you really air down but then you definitely need to stop and fill up on the way out, and again, you lose some ground clearance.

I find I'm usually not in the mood to pull over to refill after I get off the jeep trail and back onto the nearest highway...something about craving a burger, or just looking forward to getting to my next stop. Hard to say why exactly, but my brother is the same way. When it's time to go, it's time to go.

Cheers.
 

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You’re moving to dual 485c compressors you mean? And hmm the 485c is only 10% stronger than the 480c so that wouldn’t bode well for me. Maybe 4-5min based off that to go from 30->55 psi front and 45->75 psi rear.
Yes, dual 485s. On another note, I've never really had need to change my air bag pressure on the fly. When I rotate the tires I top them off a bit and make sure the van looks level and that's it. Also, have a plan for draining water out of the tank; you will need to do it frequently.
 

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2022 W2X 350 HR LWB AWD
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In your original post you mentioned the ARB. I have looked at that as well. I even wrote to ARB and they said it should not be mounted under the vehicle.

Now, in the real world… UJoint OffRoad sells a bracket to mount it under the chassis and as a whole kit. My guess is that it might eventally fail.


I have settled on the Viair because it has similar specs, is smaller and cheaper. But I’m not acquiring all my parts yet and I’m watching this thread.
 

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We have air suspension on our Sprinter. I had to replace the entire air compressor system after a few years due to moisture damage. I put a water separator in the new system. It traps a small amount of water which I drain occasionally. Small hose reel is another nice feature. I originally had the compressor under the passenger seat (photo below) which was a bad idea due to noise. Have since moved the compressor to the engine bay. More photos and information in our Sprinter build thread: 2010 3500 RV build

All the best
Hein
DIYvan

 

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Call George or one of the fine folks at Extreme Outback
I have used their stuff since 2007 (also tried lots of other options).
In my front bumper I am running a pair of the new Endura since 2019 & almost 80k miles. I do a ton of airing up and down on the trail, getting out dust from the inside & air filter and more.
With a 2gal tank and dual compressors there is more CFM than I need.
A 255/75-17 from 25psi to 50psi is 90sec per tire....yeah I look at my watch and add 1.5min to the time :)

George or whoever answers (small company, great family) will ask you questions and taylor a setup for you. Plus they have lots of little bits and pieces you need anyway.
 

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Discussion Starter · #14 · (Edited)
Thanks for the link! There stuff looks awesome, I might go for the extremeaire compressor, better specs for the price than Viair! Seems like extremeaire should be able to air up the tires in about 2 minutes each
 

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Have you considered using separate compressors for the air suspension and other needs? AirLift has this remotely controlled, wireless system which seems awesome: https://www.amazon.com/Air-Lift-74000EZ-Generation-WirelessAir/dp/B082LX2RKC

For the cars and motorcycles, I use a tiny 12v pocket-sized compressor. Your needs are perhaps different in that you want to use air to dry things, so maybe a separate compressor with a small tank? Dunno, just bringing up the wireless compressor in case you didn't know about it.
 

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Thanks for the link! There stuff looks awesome, I might go for the extremeaire compressor, better specs for the price than Viair! Seems like extremeaire should be able to air up the tires in about 2 minutes each
Like I said for 90sec to take my 33in tires from 25psi to 50psi....
Love my Extreme Air stuff and one of their compressors I installed in 2009 is still on that rig working hard and it is frame mounted UNDER the vehicle taking all the abuse.
 

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Discussion Starter · #17 ·
Have you considered using separate compressors for the air suspension and other needs? AirLift has this remotely controlled, wireless system which seems awesome: https://www.amazon.com/Air-Lift-74000EZ-Generation-WirelessAir/dp/B082LX2RKC

For the cars and motorcycles, I use a tiny 12v pocket-sized compressor. Your needs are perhaps different in that you want to use air to dry things, so maybe a separate compressor with a small tank? Dunno, just bringing up the wireless compressor in case you didn't know about it.
I have, but this adds probably $400-$500 to the total cost of the setup
 

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Running the 400P with a 2.5-gallon tank. Leave the tank disconnected most of the time. It works fantastic for mountain bike tires. It takes about 4-5 minutes per tire to air back up from 30-35 to 60-75. Not fast. Hook up the tank if we're using the air to blow out the van or clean bikes. Otherwise, the tank adds nothing.

We kept the Air Lift baby Viair for that and the 400P / tank is separate. Considered joining them, but... it works fine.
 

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I have a single compressor ARB in my landcruiser and a Viair 400 with a 5 gallon tank in my Transit. They both seem to fill tires at about the same rate...Viair might be slightly faster, but the ARB is really loud. ARB is mounted under the hood. Viair outside under the passenger seat. How often will you really use them? They are nice to have, but... I travel a lot, much of that off road and use the one in my transit mostly for filling bike tires. EDIT...oops, I forgot you said you had airbags.
 

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I do not have air bags. Needed air for van tires and e-bike tires. Instead of installing a fixed DC air system I bought a 120 volt AC portable compressor. Much less expensive and no installation of air lines or electrical.

1 Gallon 135 PSI Ultra Quiet Hand Carry Jobsite Air Compressor (harborfreight.com)
I was considering this option (still kind of am) but the major trade off with that option is they take up allot of interior space, mounting the tank under the van frees up allot of room for other gear.
 
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