|My on-board air system consists of a converted A/C compressor, a couple
small propane tanks for storage and a pressure regulator to run my ARB
My particular compressor came from an '88 - '90 Suzuki Swift.
They used two models. One with a V-belt pulley which I have, and
another with a serpentine belt pulley. Make sure you get the one
with the V-belt pulley. The Swift had a couple engine options those
years. I believe the V-belt type is used on the SOHC engine and the
serpentine type is used on the DOHC engine.
This compressor is a NipponDenso model. It is an axial piston
design. It has 6 (I think) cylinders arranged longitudally around
the circumference of the compressor. The pistons are driven via a
swash plate from the pulley and may be double ended for 12 pistons
total. I'm not really sure on the specifics of this one though as I
haven't dis-assembled it to see.
|This is the compressor compared to a
much larger York compressor. Don't let the size fool you
though. It really moves a lot of air.
||The top adjusting
bracket is made from 1" channel.
||Here you can see the
need for a very short compressor so it'd fit with the turbocharger.
There are many different axial types of A/C compressors out
there. I chose this one because it was the smallest and shortest I
could find. It normally wouldn't be a problem, but mine is a very
tight fit because of the turbocharger.
The bigger ones will move more air, but this one does quite well if you
rev the engine a bit. I can run air tools off it. Idling at
1200 rpm I used an air impact to rotate my tires with no problem.
Revved up to 2500 rpm or so, I can fill a 33x12.5" mud tire from 10
psi to 28 psi in less than a minute. I haven't actually timed it,
but I'd guess in the 30 - 40 sec range from what I remember. I'll do
some timed fillings later. A larger drive pulley on the crank would
help as well so I don't have to rev it as much.
|You can barely see the
bottom bracket. It adapts the stock alternator/air pump
bracket to fit the compressor.
||Here's the belt
arrangement using the stock air pump pulley on the crank.
||The now unused air rail
is capped with a 1/2" NPT female cap.
Because the compressor can put out very hot air (like several hundred
degrees), I routed it through a piece of 3/8" copper tubing before it
joins my plastic air line. I can tie the compressor clutch switch
into the electric fan relay to turn the fan on when the compressor is
working, but I haven't done it yet. Right now I just turn on the A/C
as well if I need to run the compressor continuously. Turning on the
A/C does kick the cooling fan on as well.
|This is the copper
cooling tube mounted in front of the A/C condensor.
||Another view looking
down. The blue thing mounted to the front bumper is the filter
/ oil separator. The valve at the bottom of it is reached
through the holes in the front facia.
The hose coming off the compressor is indended for high pressure steam
cleaners. It's rated at 350 psi @ 325º F. The air fitting to
the compressor is a quick dis-connect as well. I designed the mount
so that I could easily remove the compressor to get to the turbo, hence
the quick-disconnect. I can remove the compressor in about 2 - 3
minutes with no hassle. The dis-connect is not your standard
compressed air dis-connect. It uses a high temp silicon O-ring and
is rated for around 350º F. Standard dis-connects are rated around
125º I think.
|Here's the high temp
quick dis-connect connected...
The brass fitting on the outlet is a ½" NPT fitting. The
inlet is bigger, but smaller than ¾" NPT. It's just shy
of 1" in diameter and a 1" crankcase breather filter fits
||This is the aluminum air
manifold I'm using. It uses 3/8" fittings and tube for
the main air lines and smaller ¼" fittings and tube to
the multiple air tanks.
My old air tank was a 5 gal tank I
mounted over the rear axle. It was quite large, but un-necessary
after I got my compressor installed. I wanted to use the space for a
dual battery box and possibly a large water tank as well.
My new tanks are small propane tanks like used for camp stoves. I
used old, empty ones of course. You can buy a little brass fitting
at hardware stores that screws onto the tank and is intended to re-fill
them from larger tanks. The nipple inside the fitting comes out
though and I drilled the hole out to ¼" for better air flow.
I also drilled out the schrader type valve in the propane tanks as
well. If you do this, I'd suggest keeping the neck of the tank full
of water. You don't want a spark coming off during the drilling
process as even an empty tank still has fumes inside. I drilled the
neck out to ¼" as well.
|View looking forward
showing the tanks mounting up behind the rocker panel.
||They sit a couple inches
higher than my nerfs so they're well protected.
The tanks are mounted on the passenger side behind the rocker panel.
They are mounted high and are well protected. Right now I'm using
only two tanks. As I empty some more from camping, I'll probably add
two more to the driver's side as well. My 150 psi safety valve
is mounted to the air manifold which has enough free fittings that I can
fit as many as 4 more tanks and just plug them in.
|The mounts are pieces of
½" angle welded into the corner of the floor and rocker panel.
||A ¼" rod is welded
offset into the angle. Just enough to let the hose clamp fit
through behind it.
||The tanks mount in the
hose clamps then and they're large enough (the tanks) that they draw
up against the floor and rocker panel before they touch the rod so
they fit tight and don't rock or rattle.
I haven't done much with oiling yet. I know a lot of people that
use these type compressors just run some Slick 50 or something similar
through them once a year or so and haven't had a problem. I've just
been periodically squirting a few ounces of oil into the inlet for
lubrication. There is a website somewhere of a guy that has a
completely re-circulating oil system. Oil is filtered out after the
outlet to a reservoir and is allowed to drip back into the inlet.
Haven't gotten that far yet though.
|A view from the back
side. There is a small schrader type valve on the inlet that I
use to squirt oil in through periodically. This is an ideal
place to fit a hose for an automatic, closed circuit oiling system.
Some final notes:
This compressor does require the removal of the smog pump. That
pump though only does any work at startup for a few minutes until the
engine is warm. If you really wanted to, you could run your
compressor all the time to keep tank pressure up, then run a large (for
volume), regulated (for low pressure) line to the air rail and switch it
with the same signals used to switch the smog pump. I don't think
I'll be doing that much though.
To remove the pump, I pull off the upper tensioning bracket and a bolt
from the front of the lower bracket. The compressor then pushes back
about ¼" - ½" and pulls strait up. To remove the lower
bracket though, I have to remove the large smog pump / alternator bracket.
The large bolt on this bracket is inserted from the rear and I can't do
that when the bracket's on the engine because of the turbo so the adapter
has to be installed to the stock bracket before it itself is bolted back
I'm using an air compressor switch to turn the compressor on around 90
psi and off around 130 psi. I use a pressure regulator to knock this
down to around 70 - 80 psi for the ARB though. The switch is not the
ideal type though as it mounts in the air line in parallel. i.e.
air pressure is routed to it, not through it. Look for one that
routes air through it and has a check valve. Right now I don't have
a check valve and the air will bleed back through the compressor when it's
off. Pressure drops enough to kick the compressor back on every 5 -
10 minutes or so.
And finally, all the hoses and fitting came from McMaster Carr
(www.mcmaster.com). I can't say enough good things about this place.
They literally have just about anything industrial you'd need and their
web site is excellent for searching and ordering. The down side is
that they won't send you a print catalog, so if you don't know what you
want or don't know what it's called, it's hard to search for it on the
My air lines are high pressure Nylon 11 lines and I use the instant
fittings for them. Nylon 7 will work as well. It's stronger,
but much stiffer and doesn't bend as well. These fittings are the
type you just push in to connect. To dis-connect, you push the line
in, pull and hold the collar down and the line will pull back out.
They're air-tight and very easy to connect and dis-connect for re-routing
lines or whatever.
For the main lines that *all* the air goes through, I use 3/8".
For the lines from the manifold to the multiple air tanks, I use smaller
¼" since they all work in parallel and don't have to pass as much
Any questions or comments? Give me a shout.
Created by: Dan
This page was last updated on 14 Apr 2004