Today I did some timing checks on the AS Air-Bags.

To complete the 2" lift took 38s from Left isolation-valve open to Left isolation-valve close. The Tech2 displays the inflation window on the graph.


The cycle starts with the compressor pressurising the system to match the last recorded air-bag pressure, otherwise opening the valve prematurely would cause the bag to deflate.

Once the pressures match, the valve is opened and the bag inflated until 2" is achieved. Interestingly the compressor kept going presumably adjusting the Right Air-Bag (hard to tell)

To get some idea of volume I measured a spare air-bag, estimated its internal volume and then increased it by 2" From this increase was 0.57 litres (0.020 cu ft)

So 0.57 litres took 38s which is 0.015 litres/min or 0.00053 cu inches/min.

Keep these figures in mind and see if they relate to any compressors you look at. If things seem "out" I can always run the tests again, it's not difficult.

 

Thanks Ocean, those are very interesting results, considering the size of the bags the H2 uses I never thought the pressures would be that high, I knew it would require a decent pump and now i understand why GM went with the dual pumps in the second generation.
Looking at the schematic without a doubt it would be easier to make a harness from the air suspension module to interface with the BCM then it would be to build some sort of control unit. I imagine the air suspension module is part of the compressor assembly and located on the compressor.shelf.
This must be the control module MixmanSC mentioned he took off the first style shelf he as.

Again I want to thank you both for provided such helpful information, This is really a great forum with so many knowledgable members always willing to help.

 

With an aftermarket controller it is vastly more simple. On my S10 I have the analog Air Lift control. The analog control does require running a pair of air lines inside to the gauge/switch panel they provide but really not that hard to do. Has a 3 position momentary toggle switch to inflate (mid is off, push left to inflate left bag, right to inflate right). That controls two solenoids from the air tank which go to each air bag, and also has tees which goes inside to the control panel for the pressure gauges and deflate buttons. There are two push buttons, one to deflate each bag, and it lets the air out right there at the button, you can hear it hissing out when you press one. The compressor has a pressure switch on the air line to the tank and also tees off to the two air bag solenoids. The pressure switch is inline with the positive to the compressor and simply cuts power (ignition) once the line (and tank) pressure hits 110 psi. The bags from Air Lift state to keep a minimum of 10 psi in each bag, and they are rated for up to 100 psi each depending on the load and comfort level desired. I generally without a load keep them at around 20 to 30 psi and with a couple thousand pounds on the bed have had them as high as about 80 psi.

Then as mentioned, I added another tee to the air line to the tank and a third solenoid to run an air horn. Then from the tank I also added a schrader valve which is mounted so that I can use a GM style tire and accessory inflator (same on in the H2 with the red hose and gauge). The nice thing with the air tank is when I need to add air to the air bags, it is dead silent, the compressor will only cut on when the pressure gets too low in the tank to inflate them or if I use the horn a lot.

Extremely simple. The digital control ones are only a little more complex in that those also need solenoids to deflate is all.

Also they sell the controls for independent bag control with dual pressures or a single pressure setup which just tees to the bags and keeps them both at the exact same pressure which is even simpler yet.

 

MixmanSC what do you think about this: I don't know if its really important for a dual system one for each bag or if I could simply get away with the single line with a tee tying both bags together. If I measure my SUT both sides are within 1/8 inch of the other so i'm not sure I need the dual system,
The only issue is would the compressor be able to keep up with the large H2 Air bags? I imagine it would just need to run longer. Other then the mounting parts for the bags and the 1/4" to 6mm line converter this looks like it could be the ticket.

Just install, set pressure to achieve the correct rear height. I would imagine the pressure would be close to the 67psi Ocean noted in his tests. Simply crank up the pressure when you add a load and bingo you have the best of all worlds without all the complications of the factory system!
A great aftermarket solution for those with failing factory compressors or components of the factory system. Its true you will have to find a place in the cab to mount all the hardware and its not as clean as the factory button but hell, a small price to pay to get back to the nice ride and flexibility
the air system makes for towing or heavy loads placed in the back.

 

some aftermarket kits do come with ride height sensors

 

@H2-SUT regarding the Tech2's air pressure readings, this thread which may be of interest to you

The point is the base-line air pressure reading of 41psi seems odd, normal atmospheric is14.7psi which you'd expect this reading to be if the readings were absolute and not relative.

Thus it would seem logical to correct all readings by subtracting 41, i.e. In my tests the final 2" levelling reading was 72, converting this yields 31psi, much more sensible.

The max pressure recorded was 88, minus 41 gives 47psi again more sensible.

Please bear this anomaly in mind.

 

I think that Air Lift system would work just fine, even the single path version (which is a lot cheaper). Air Lift also sells the exact same system but with an air tank which is their "Quick Shot" setup. That is what I actually just converted mine to by adding an air tank and pressure switch but that is not really needed. Their compressor is very good and it deals with the much longer run time of filling the air tank no problem. Only difference between the one you linked on Amazon and the one I have is mine is the older dual gauge, dual path version (LoadController I/II) which works pretty much the same. In my setup, a custom S10 tow truck, the dual path option is helpful as might might load a pallet of concrete from the side of the bed so being able to inflate just one side or one side much more than the other if very helpful.

If I were adding this to an H2 myself, I'd go with the single version and just let it put the same pressure in both sides.

If you are curious - this is my S10..... Custom stretched frame, 1 ton dually axle. It is a 1983 chassis with a 1993 Vortec drivetrain and electrical system, with a custom stretched frame, 1 ton dually axle, and a 16 foot hydraulic bed, 8,000lb winch. Handy to have. I can get the H2 on it, but that is really pushing its limits for weight and more than I really like to haul on it.

 

I can confirm that you can use standard (not metric) lines between compressors and for the air intake. I have replaced my compressor assembly with a brand new OEM (still available), and had to lengthen the air pickup (the filter located right behind the tire sucks mud into the air compressors and kills them).

I used SMC brand tubing, identical to what comes on the OEM setup, to lengthen the air pickup line and relocate the filter higher in the vehicle.
Brand: SMC
Type: polyurethane tubing
Size: 3/8" OD (approx 7/32" ID)
Color: available in a multitude of colors. Black is stock on the H2

The thin, very rigid tubing that goes from compressor to the air bags, not sure where to get that, but it is likely off-the-shelf tubing also.
Bet SMC has that available. But the OEM stuff is molded into shape. But you can heat-mold it yourself with a heat gun.

 

What is the best option for replacing all factory shocks on 2009 HT3? Any help would be greatly appreciated.

James

 

this thread is for H2 air suspension conversion not H3T