On the high end of things all of the Airnoids can improve the fill time of
any system and do a better job of packing the lines. You may be able to
tell that I prefer that the jets to be the final restriction and not the

In some cases where rules dictate a single solenoid there is a lack of
capacity to fill the jet sizes available. Double bar plates come to mind. Any
of the Airnoids can improve this situation substantially. The highest
flowing electric nitrous solenoid I currently use has a .250 orifice and flows
4117 lbs/hr. This is way overkill for most applications but the FS500 blue
single does it one better which now makes it the baddest valve on the
planet, hands down.

The story is similar with the fuel. My best electric Nitrous Master .250
orifice fuel solenoid flows 982 lbs/hr and using the FS500 Airnoid as a fuel
valve would be even better and it has a smaller orifice and lighter weight.
The individual 500 series fuel Airnoid was designed to replace the currently
most used .157 fuel solenoid and it achieves this goal and then some.
Future versions of the FS500 promise to have even more flow capacity.
While the Silver and Gold units share common orifice sizes the bottom
outlet of the Gold unit allows it to have a higher flow rate than the Silver.

You may be wondering about the single nitrous Airnoid being tested with
fuel. I tested the NS500 Airnoid on fuel because it can also be used as a
fuel Airnoid. See the Fun and Games section.

The high plunger lift of the Airnoids allows for some plunger wear without
reducing flow. This will reduce or even eliminate changing plungers on a
regular basis. Some electric solenoids don't lift the plunger enough to allow
the maximum flow the orifice can provide. Some actually lift just enough
but there is a catch to "just enough". As the plunger material embeds itself
into the seat the flow is reduced due to the material located in the center
of the plunger pushing out and down creating an expanding bubble into
the orifice. This reduction in flow sneaks up on the tuner and makes the
system progressively richer as time goes on. The flow starts out at 100
percent capacity but as time goes on it could drop as low as 50 percent.
Basically this bubble that is growing in the opposite direction reduces the
effective lift available and forces one to change the plunger from time to
time. The high lift of the Airnoids means that even if it was badly bubbled
it would still have more flow than electrics in good shape.

To compare things, electric nitrous solenoids lift the plunger anywhere
from .015 to .045 depending on the orifice size. The Airnoids lift a
minimum of .080 to .100 giving you a lot more wiggle room before
maintenance is required. Perhaps replacement may never be needed. Of
course, if you run some junk through it then plunger replacement is
mandatory. Another feature that reduces or almost eliminates wear is the
way air operated valves close. Electric solenoids depend on the 900+ lbs
of pressure to slam the plunger closed and hold it down on the seat. This
"slam" is what is so hard on the plunger seat material. The Airnoids dump
off the co2 to the atmosphere and the return spring handles the job of
holding it closed. This is similar to the closing ramp on a modern roller
cam and valve spring. It's a much softer hit when it closes.

Some of you will get around to checking the cost of the Airnoids and will
initially have your eyes roll to the back of your head. But wait, it's not that
bad. When figuring the cost of 2 solenoids that have the capacity and
convenience of the Combo Airnoids you will find they are within $10-20
bucks or each other. Seems like a win/win deal to me.

I almost forgot. The Airnoids all have bolt holes for use with custom made
mounting brackets.
A Review of Combo-Flo  Air Operated Solenoids
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Combo-Flo 500 plate air operted solenoid
By David Koehler
copyright 11-30-05