Outer Limits 4x4 Board

Hi,
Can anyone tell me the speed an aircon compressor needs to go to be useful as an air compressor. I have searched and found that a Sanden type could possibly flow 4cfm at 1000rpm (engine) and 8cfm at 2000rpm (engine) I dont know the engine belt/pulley reduction so would like to know the actual compressor RPM at those engine speeds. Perhaps an aircon tech can tell me.

I have found a source of large electric motors, and one may be able to drive one of these compressors.

Also, is there a reason the Sanden and York compressors are most popular or would any compressor work - I am thinking maybe newer design compressors, from late model small cars, may be able to flow as much in a smaller package.

thanks
Grazza

Basically pretty much any aircon compressor will work as long as it has lubrication.
The Sanden ones are good i think as theyve been used a lot and have proven reliable, the York ones are used, as they are a standard piston and crank design which gets its lubrication from oil in its crankcase.
As for an electric motor driving the compressor in your car, i wouldnt recommend it, as youre alternator is going to labour the engine anyway to keep up with the requirements of a motor large enough to run the compressor, plus then you also have electrical and mechanical losses which would make it less efficient as driving it directly off a belt on the engine.

I don't think you'll find a sanden putting out 8cfm. I have a york 210 which is a MUCH bigger compressor and it puts out about 9cfm.
The York is a good choice because it has a large capacity, has it's own oiling resiovior and its relatively commonly found if parts etc are required. The downside is that they are more bulky and more akward to mount.

Personally I would not run a york or sanden using 12V either - just too much drain on the electrical system - and besides if you have it well mounted in the vehcile why not utilise the egnine power much more efficiently.....

BTW did I mention I love my york

Geez, how much air do you want?
I run a Sandon 508, and over the weekend, inflated 3 31's from 20 to 32 psi in the time it took the forth tyre to be inflated to the same pressure by a name brand electric compressor, and that was at idle speed of around 800rpm. If I crank the idle up to anywhere over 1500rpm, the compressor is pumping faster than the air hose can deliver the air to the tyre, and thats with a cut out pressure switch at 120psi.

By electric motor I assume you mean 12v??

Wont work, Ive burnt out 2 winch motors trying tho achieve this.

Bazzle

Thanks for the advice.

I would love to run one off my motor but no room...and I need the aircon in QLD

I was just interested in seeing if I could get one to run off a big electric motor, leaving the engine running.

I guess I am inspired by the Trailhead.


Since posting that link, I read an article sayiing it pulls 150A!!! which is about 10 times what the motor I had in mind will do.

Oh well...back to the drawing board.

grazza wrote:Hi,
Can anyone tell me the speed an aircon compressor needs to go to be useful as an air compressor. I have searched and found that a Sanden type could possibly flow 4cfm at 1000rpm (engine) and 8cfm at 2000rpm (engine) I dont know the engine belt/pulley reduction so would like to know the actual compressor RPM at those engine speeds. Perhaps an aircon tech can tell me.

I have found a source of large electric motors, and one may be able to drive one of these compressors.

Also, is there a reason the Sanden and York compressors are most popular or would any compressor work - I am thinking maybe newer design compressors, from late model small cars, may be able to flow as much in a smaller package.

thanks
Grazza

If you go to a pick-a-part you should be able to measure the aircon pulley and the engine pulley. From a wild guess the air con is probably 75% of the size of the engine pulley so you'd be talking 1500 rpm/3000rpm if your cfm estimates are correct.

Some setups have the air compressor as a temporary fitment, that is, they are placed on top of the engine with the bonnet up, with a belt around a spare pulley (eg a double pulley on the alternator) and operated that way. In other words you don't necessarily need permanent room, just temporary room.

It would be interesting to see if you could run one on the PTO output...

Be careful as late model small compressors are scroll type compressors and will not do the job your after
you must use a piston type compressor

mavzilla wrote:Be careful as late model small compressors are scroll type compressors and will not do the job your after
you must use a piston type compressor

Isnt a Sanden a scroll type?

I was at the wreckers yesterday and picked up a cheap Daewoo compressor, it was a lot more compact than the older ones. I pulled it off a car since I wanted all the hoses and brackets. It has 5 pistons, scroll type.
Think I have made a mistake, as you pointed out. I will see if I can swap it for a bigger compressor.

I ran it off my power drill - about 2500rpm - and hardly any pressure builds up at either port. Perhaps I need to "load it up" with pressure first, like put a full tyre on one port and then try. I pulled it apart and cleaned up a bit of minor surface rust on the gaskets ( ) and it all appears in good working order.

Should I expect to get air rushing out of the ports?

Interesting things when you pull them apart.

grazza wrote:

mavzilla wrote:Be careful as late model small compressors are scroll type compressors and will not do the job your after
you must use a piston type compressor

Isnt a Sanden a scroll type?

I was at the wreckers yesterday and picked up a cheap Daewoo compressor, it was a lot more compact than the older ones. I pulled it off a car since I wanted all the hoses and brackets. It has 5 pistons, scroll type.
Think I have made a mistake, as you pointed out. I will see if I can swap it for a bigger compressor.

I ran it off my power drill - about 2500rpm - and hardly any pressure builds up at either port. Perhaps I need to "load it up" with pressure first, like put a full tyre on one port and then try. I pulled it apart and cleaned up a bit of minor surface rust on the gaskets ( ) and it all appears in good working order.

Should I expect to get air rushing out of the ports?

Interesting things when you pull them apart.

I had the same experience with a Sanden compressor from a commodore that I got for free. It was a scroll type, and like you I found it really interesting to take apart.

But it didn't produce the kind of pressure you'd need.

However, other Sandens are not scroll type, they are genuine piston types, the Sanden 508 and 510, possibly some others. The 508 is pretty common on old sigmas and I am not sure what else; I saw at least a dozen at pick-a-part last time I was there.

So, not all sandens are equal.

Jason

I've mounted two Sandens now on different vehicles, each from VB Commodores, cost almost nothing from the wreckers, and had no probs in years of operation. They put out plently of air, and I think they are the scoll types. I did pull one apart once and it had scrolls in it.

They don't seem to put out much air initially, especially when turned by hand, but when pressure builds they just keep pumping and pumping!

Got to make sure they are not corroded inside. Turn them by hand to test, they should turn easily and at least put some pressure on the outlet port when turned by hand - put you thumb over the port and rotate the pully, you should feel the pressure build up.

Reddo wrote:I've mounted two Sandens now on different vehicles, each from VB Commodores, cost almost nothing from the wreckers, and had no probs in years of operation. They put out plently of air, and I think they are the scoll types. I did pull one apart once and it had scrolls in it.

They don't seem to put out much air initially, especially when turned by hand, but when pressure builds they just keep pumping and pumping!

Got to make sure they are not corroded inside. Turn them by hand to test, they should turn easily and at least put some pressure on the outlet port when turned by hand - put you thumb over the port and rotate the pully, you should feel the pressure build up.

Really? Interesting. I got as far as making a bracket to fit the free commo one I got, then gave up before I added the bit to reposition the power steering pump, because I heard the scroll types were no good. If you reckon they are good enough then maybe I should do a trial fit of it... hmm.

I must admit when I researched it it seems that a/c compressors have to work much harder for air con than an air compressor, something in the several hundreds of psi, not just 120ish which is the most we would want.

Jason

I swapped the Daewoo compressor for a Sanden TRS105 from a VR Commodore - could not find a Sanden 508 or York. It rotates freely and some air pressure is generated when I spin it from my electric drill. Not a massive amount however but more than the piston-type Daewoo.

I will attach it to a full tyre and spin it over with the power drill, if possible, and see if it pumps it up at all.

I think this is scroll type as I pulled off the top and there was a heap of large ball bearings in it, and I can see a non-piston type action from the ports. Quite different to the Daewoo.

Anyone know where I can get an electric generator? Not an alternator. I believe old cars and tractors used generators but I was hoping someone could provide a more specific source.

Just thinking an old generator may make a useable motor - no harm in asking

Starter motor. People will tell you they can't run for long but it depends on the starter motor - you need to find one suitably durable.