Is it worth it to build an air tank in the front bumper?

panion · 02-01-2009, 12:45 PM

Hey all,

I'm going to start on my front bumper build next week. I had planned on making an air tank within the bumper to facilitate faster tire re-inflating. Unfortunately my engineering friend did the math for me and said I could only air up one tire to half pressure with my "tank".

I had this great plan of turning on the compressor when I aired down the tires. Tank fills while offroad. Back to the pavement, quickly air up, bumper is depressurized and safe.

Here are the parts in question.

33 inch tires by 11.5 wide. Viar compressor. Looking at a "tank" about 8 feet long and 4 inch square. I usually air down to 20 - 25 and run 60lbs on the highway. I believe my viar will go to 120psi.

Question:
Is my friends math correct? If so it's entirely not worth it. Back to the old plan of an inline regulator and a locking air chuck.

Tom.

Jeffrey · 02-01-2009, 01:53 PM

Tom, a tank that size will only be useful working in conjunction with a compressor. Alone, your friend is correct.

You said "I had this great plan of turning on the compressor when I aired down the tires."

What's that about?

AndrewST · 02-01-2009, 02:05 PM

The air tank is helpfull if you need to take the tyre off the rim to repair a flat.
It will give you a large volume of air quickly helping re-installing the tyre on the rim.
Only with the compressor, it won't be as easy.

Now to inflate the tyres from a tank, you need it to go high in pressure to be efficient.
For a one time re-inflate, I have over inflated my spare and it was enough for the 4 tyres back up to road pressure (size 32x11.5 R15).

panion · 02-01-2009, 02:55 PM

Interesting idea AnsrewST. Unfortunately my "tank" won't be strong enough for much more than 100psi.

panion · 02-01-2009, 02:57 PM

Quote:

Originally Posted by Jeffrey

Tom, a tank that size will only be useful working in conjunction with a compressor. Alone, your friend is correct.

You said "I had this great plan of turning on the compressor when I aired down the tires."

What's that about?

That meant run the compressor while offroad to fill the tank knowing that I would need the pressure for the refill.

jage · 02-01-2009, 09:57 PM

Volume and speed being required to set a bead are a myth- yes you can, yes it's easier (no patience needed) but, you can also reset a bead with pressure and not volume. I've successfully done it 7 or 8 times with 32" BFG Mud TAs with my Quickair I, a unit which isn't much faster than a Walmart backup, but has enough pressure to seat the bead.

I'm not sure I see an issue with running a pressurized bumper. I know Jeep and Bronco guys who do it, but of course that's steel... still, it's attached to the van and it's not like you're running 250psi or something ridiculous.

It's not going to explode per se, and when a high pressure tank ruptures the danger is more from the tank being projected, or that the contents are volitile. If you're in an accident large enough to rupture the bumper, you're way beyond the damage so little air pressure is going to do... I'm not saying for sure, I'm just saying it doesn't seem that much more dangerous than a front mounted spare, for example.

Any tank is better than none, and like other people said the tank is supplimenting your air compressor, which will be running while you fill anyway. Whether it's worth the trouble... well that's up to you I guess.

You could probably get the same results from a locking chuck, less the first tire, but the other answer is a bigger tank- use the other half of the bumper too, put it somewhere else, etc.

yvrr · 02-02-2009, 08:46 AM

You aren't gaining anything by having a tank in the system when you are airing up tires...the tank isn't an advantage. If you wait until the tank is full before starting to air up, the compressor will still come on the minute you start airing up. Then the compressor is trying to fill the tank and the tires at the same time and you've wasted the time it took for the tank to fill up. There is a slight advantage in having a tank when using air tools (but you still have to wait for the tank to fill between cycles). And there isn't a problem having the compressor running while you move from tire to tire without a tank.

Since I already had a tank, I added a valve to take the tank out of the loop while airing up. See

www.sportsmobileforum.com/viewtopic.php ... sor#p13931

for a photo and more discussion...

jage · 02-02-2009, 10:37 AM

From my own experience yvrr, that's not true. The tank is overpressured compared to the tire, and depending on the volume can fill a good bit without running the compressor. Once you're down and the compressor is running to keep the tank filled, your only advantage is trapping time between, where the compressor runs to refill the tank as you're moving from tire to tire.

Whether or not the benefit is there on a vehicle sized unit, I'm not sure, these observations are from using my garage unit, which is a bit large even for the van.

Another alternative is to have dual compressors. Twice the air in one system. I'm working on that, but I'm having trouble finding the right sized fittings as the compressors have 3 thread sizes on the head.

neeemo · 02-02-2009, 12:14 PM

Quote:

Originally Posted by yvrr

You aren't gaining anything by having a tank in the system when you are airing up tires...the tank isn't an advantage. If you wait until the tank is full before starting to air up, the compressor will still come on the minute you start airing up. Then the compressor is trying to fill the tank and the tires at the same time and you've wasted the time it took for the tank to fill up. There is a slight advantage in having a tank when using air tools (but you still have to wait for the tank to fill between cycles). And there isn't a problem having the compressor running while you move from tire to tire without a tank.

When I added on-board air systems to my VW Syncros, I made it so the tank was always pressurized. The pump will run--only when the engine is running-- to automatically fill the system when needed or when using the compressed air. It's a seamless set-up. I used to run them at 150psi, which filled up tires really quickly. I'm going to try and rig up a similar tank and auto-fill system with my Powerplant.

Tom

Christopher Thwaites · 02-10-2009, 02:23 PM

I bought a 3 gallon tank fillable to 125lbs. It will only refill one tire to about 50lbs from 25lbs. when fully pressurized so I really didn't gain much over my ARB compressor. It takes as much time to add 50lbs to the tank as it does to my tire....duh! I took the tank back and got a refund.
I am curious as to how an overinflated spare has enough air to reinflate 4 tires???? Can you splain me Lucy?