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 may 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

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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.

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/wind deal to me.

I almost forgot. The Airnoids all have bolt holes for use with custom made mounting brackets.

Torture Tests

Plunger Wear

I used the Racing Instrumentation Progressive Controller you read about last month to see how bad I could wear the nitrous plunger. I set it to pulse the NS500 single Airnoid for the full 10 seconds and just continued to run bench pass after bench pass after bench pass. I have to say that this was one of the more boring things I have ever done. I started with a fresh plunger and made 200 passes. With the pulse rate speeding things up this amounted to 4000 hits on the plunger. The end result was that the center bubble of the plunger material moved .004 which still left me with .074 of effective lift capacity. Since I only need .055 plunger of lift to fully utilize the orifice size I am in good shape. Pretty good I think. I will trim the bubble off in the lathe and run this test later when time permits to see if it takes a set or at least slows down the bubble growth. That would be cool.

The Clear Top

I was curious about the clear top on the 400 and 450 series. Granted you could break it with a hammer, or if you roll the car, but I think it would hold up just fine to normal use. I sprayed it down with gasoline, methanol, shop solvent, acetone, brake fluid and a couple of other mystery chemicals and none of these bothered the finish. I was out of nitro or I would have tried that particularly interesting cleaning solvent.

The only thing I found so far that could attack it was CRC non chlorinated Brake Cleaner. Most of us that use brake cleaner know it to be some good stuff but nasty on many things like paint, powder coating and anodized components so don’t use it to clean the Airnoids. You have been warned.