Re: Onboard Air

[jlandry@domain.elided (John A. Landry)]

On Sun, 21 Dec 1997 22:34:55 -0700 (MST), Tom Mandera <tsm1@domain.elided>
wrote:

>So how would an on-board air compare?  I've heard they can flow a good 
>deal of air, at some rather high pressures.. but, assuming it's all 
>capped off at 150psi (run 90-125), what type of cfm would I be looking 
>at, at idle and at 2000rpm? (or wherever).

Tom,

We have discussed this in detail a couple of months ago, but I don't think
anyone has yet measured the cfm of the IH York compressor.  I personally
don't have any device to measure it.  All I can do is offer you my
subjective observations.

I found the cfm definitely increases in relation the compressor rpm.  At
normal engine idle the flow is moderate, but it gets pretty darn impressive
at a fast idle, say in the neighborhood of 1200 rpm.  This is why I
installed a throttle lock.

At a slightly fast idle (I don't have an on-board tach, so I can't offer
specific numbers), I can inflate my 31x10.5-R15LT's from about 15 psi to 45
psi in about 45 seconds per tire.  Not too shabby for it's main use.

I used my compressor setup with a tank installed to sand blast an old the
dirty old IH four barrel intake manifold I bought for my Scout.  This was
one of those Sears sandblasting kits that I think recommends a 5 hp
compressor (not sure the cfm requirements, but it's pretty high).  At a
fast engine idle, the York compressor could not quite keep up for
continuous sand blasting.  I would blast for about 30 seconds and as the
effectiveness of the blasting wore off, I'd let the air tank refill for
about the same.  Worked like a charm.  I had the thing running for over an
hour cleaning all sorts of parts I had lying around.

I think it definitely work great for *occasional* use of just about any air
tool.  But don't expect to be able to run a die grinder continuously
without some tank recovery time.  For home use on small projects, it's
great... not very energy efficient though with that monster motor sucking
the gasoline. <grin>

>Also, what "hp" rating would 
>it be the equivalent of?

What's the horsepower of your engine? <grin>

>Would I be able to use my on-board air system 
>to... oh, say.. PAINT my Scout?

I'd say *yes* with a couple of important considerations.

1. I really don't think the York compressor is capable of running a High
Volume Low Pressure (HVLP) spray gun.  This type gun takes *a lot* of air.
The York compressor is capable of very high pressures, but the cfm rating
is only moderate.  With an air tank hooked up, I don't see why the York
compressor wouldn't handle the job with a regular spray gun... as long as
you don't expect to be able to paint continuously.  You again may have to
let the tank recover now and then.

2. I would never consider trying to paint the vehicle in which the
compressor is installed!  I think you'd clog the engine intake and air
compressor intake in short order.  I don't see how you'd avoid that.  But
to maybe touch up or repaint something like a fender... maybe.

>I'm thinking of setting up BOTH of my Scouts with on-board air.. John 
>Landry's stories of "normal" people's AWE when he pulls out the air line 
>to air up their tires has me convinced.. plus the coolness factor of 
>pulling out an impact wrench to help someone change out a tire on the 
>trail (or more stubborn bolts).

It is handy no doubt.  My biggest problem is that many times when I'm doing
engine work, I'd like to use it *on* the Traveler that it's mounted on.  I
haven't figured out how to have the engine running while taking it apart at
the same time.  But seriously, if I know I'm going to need air to operate
an impact wrench to do something like remove the alternator pulley, I'll
charge up the air tank before hand and that will usually be enough to get
the job done.

>I was thinking I could just park my '77, with the 196, outside of the 
>garage, and run the hose inside for paint spraying or sand blasting or.. 
>whatever duty on the '72.  Granted, it'll cost some gas money.. but, if 
>it gets too bad I'll just buy a "real" compressor for the garage.

This would probably work fine.  Just make sure you use a good air line
filtering system, regulator and liquid separator.  If you buy a used
compressor at a junk yard, you can be assured that some compressor oil
seeped into the head when it was thrown in a pile and stored upside down.
Without removing the head, this oil takes a while to blow it's way out.
Mine is clear now, but it many hours of use and countless filter drainings.
Now the air runs clean.

>I also plan to mount an air tank of some sort under the bed of my 
>Scouts.. put it just behind the "step" and in front of the rear diff.  
>Should do just fine under there, though draining any water out might not 
>be as easy as I'd like.. Not sure what size to use.. find a used semi 
>brake tank, or spend the $35 for a 12gallon tank at Walmart.. 

If you use a good liquid separator up under the hood by the compressor, the
need to drain the tank will be very far and few in between.  Too bad you're
not honey mooning to the NW Binder Roundup this year... you could have
taken a look at my setup.  Oh well!  <grin>

Happy holidays,

John
------------------------------------------------------------------------
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