The Mad Hat Man

The Mad Hat Man

Well-Known Member
LZIR Despatch Agent
@battenberg @wammers

i want to fit on-board air to my 200tdi disco. I have a d2 compressor and air reservoir, but is there anything else i would need as part of the system to enable it to work?
pressure switch, etc?

has anyone done this already? (I looked and couldnt see anything).
 
It depends on what you're thinking of trying to use the suspension compressor for, are you sure that the motor is capable of running in a different duty cycle? For instance, the suspension calls for the compressor to run in very short bursts, even if it's called to inflate to the "off-road mode". Tyre inflation or paint spraying calls for a totally different duty cycle.
The suspension compressor might be satisfactory for air operated differential lockers which I believe work on air pressure rather than airflow, but I could well be wrong.
 
it will be running thru a reservoir tho, that will reduce the duty cycle somewhat, but my Q is to ascertain and resolve any issues :).
 
searched google, it has been done and a few have said the compressor is 100% duty cycle, as is the p38 one, preassure switch to set cutoff, and feeds for power required with suitable fusing :)
certainly possible though from what i can see :)
 
disco me said:
searched google, it has been done and a few have said the compressor is 100% duty cycle, as is the p38 one, preassure switch to set cutoff, and feeds for power required with suitable fusing :)
certainly possible though from what i can see :)
Click to expand...
brill :)

I couldnt find any, but have now found a couple. would still appreciate words of wisdom from those that know the air suspension system much better than I as most seem to use it on an existing air system, rather than building one from scratch.

http://www.rangerovers.net/outfitting/air/airsupply.html
http://www.rangerovers.net/outfitting/air/arbair.html
 
http://forums.lr4x4.com/topic/6470-could-a-discovery-ii-air-suspension-compressor-inflate-tyres/
though i have also seen---------------
quote_icon.png
Originally Posted by mr bounce
I've got a 2004 D2 and the previous owner installed coils in place of the air bags. The compressor is still in situ but disconnected. Could it be used for this purpose or is it too small output wise? Maybe just needs an air receiver?
The standard compressor on the D2 for the air suspension has a mind boggling 5% duty cycle. In simple terms, what that means is that if you use it for every 5 min , you have to wait 95 min (over 1.5 hrs) before you use it again). Typically compressor duty cycles are based on a 1 hour period, so you can use it for between 2 to 3 minutes every 1 hour. For self leveling suspension, this is supposed to be ok, except when they get a leak, even a small one, as the compressor is on for more than it should be, which means it burns out. So, in practical terms, the standard compressor is pretty well useless, even for the job it is designed for.
----------------------

another possibility is an air con compressor
http://forum.landrovernet.com/showthread.php/191589-Air-conditioning-compressor-to-compress-air
 
i dont want to use an air con compressor as it needs to have lubricant in the air supply.
 
Last edited:
In a nutshell: the D2 SLS compressor is not a good choice for that job, better use a cheap HD mini tyre inflator compressor fed through a pressure switch connected to the tank
 
It was explained why, extremely low duty cycle,,, the SLABS ECU cuts it's feed when it exceeds it's duty cycle to not burn out,. knock yoursef out and use it if you want just dont put it in a place where the car can go up in flames from it if it starts glowing after 3 minutes of pumping
 
sierrafery said:
It was explained why, extremely low duty cycle,,, the SLABS ECU cuts it's feed when it exceeds it's duty cycle to not burn out,. knock yoursef out and use it if you want just dont put it in a place where the car can go up in flames from it if it starts glowing after 3 minutes of pumping
Click to expand...
Although I do not doubt what you say, I have also read this.....
"The air compressor has been criticized by some for being inadequate in capacity and too expensive, but in reality it is a sturdy industrial 1/5 horsepower 20 amp "Wobl" piston unit made by Thomas Pumps, one of the best-known manufacturers in the world. It is a member of the Thomas Pumps 315 model series (see details below), has a flow rate of about 0.96 cfm at low pressure, and according to justcompressor.com (http://www.justaimlinks.com/compressor_thomas.htm) it can fill a 3 gallon tank from 0 to 150 psi in 4 minutes 45 seconds. It is commonly used by low rider fans to pump up their vehicles. It has to keep the 10 liter (2.5 gallon) air tank charged up to 10 bar (150 psi), which is a much higher pressure than most off-road air compressers can reach. The compressor also has a much harder life than the average air compressor, having to operate in hot conditions (it is rated at 158 degrees ambient) for hundreds of hours rather than a few minutes at a time. "

Also "The disco unit is a better design than the RR and will likely last longer too!"
"Starting at 120psi, it had enough air to inflate the four tyres from 18psi to 30psi pretty quick or enough to change a tyre with a rattle gun. It took about half an hour to get the spare up to pressure."
 
The Mad Hat Man said:
.....it is a sturdy industrial 1/5 horsepower 20 amp "Wobl" piston unit made by Thomas Pumps,....
Click to expand...
IMOt that guy is speaking about some other pump cos the SLS pump is made by Wabco and it was conceived for it's purpose so underwinded as to deliver much in short time then stop.... you can make your own bench test, connect it to the tank and let it run 3 minutes stop 1 minute and start it again ...eventually use the stup to inflate a tyre then you'll see if it fits your needs or not
 
That was what was going to do, hence my original Q if what bits do I need?
Pump and reservoir obviously wired through a relay triggered by the overheat wire. I can see that. I assume I will need some form of max pressure regulation, or is that built in? Also will need output regulation and gauge. Anything else?
 
the compressor has a mechanical overpressure valve in it to protect the bags from blowing which i dont know at what pressure works cos it's not mentioned so you need a on/off pressure switch on the tank with the cut-off pressure below the compressor's valve, somethink like this http://www.ebay.co.uk/itm/Heavy-Dut...220860?hash=item4b134ade3c:g:2jEAAOSwCU1YwGkE with the proper values, i dunno how the valve is set but the bags are at about 70 psi inflated...for me it seems inexpedient to fit such compressor for on-board air setup, IMO you better sell it for good money and get a proper HD tyre inflator
 
sierrafery said:
the compressor has a mechanical overpressure valve in it to protect the bags from blowing which i dont know at what pressure works cos it's not mentioned so you need a on/off pressure switch on the tank with the cut-off pressure below the compressor's valve, somethink like this http://www.ebay.co.uk/itm/Heavy-Dut...220860?hash=item4b134ade3c:g:2jEAAOSwCU1YwGkE with the proper values, i dunno how the valve is set but the bags are at about 70 psi inflated...for me it seems inexpedient to fit such compressor for on-board air setup, IMO you better sell it for good money and get a proper HD tyre inflator
Click to expand...
kool, ta :)
 
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