Читать книгу How to Install and Tune Nitrous Oxide Systems - Bob McClurg - Страница 17

Simply put, a solenoid is an electrically activated on/off valve that controls fuel flow (which could be either gasoline or alcohol) and nitrous oxide flow at the flick of a switch. When it comes to actual construction, some solenoids are manufactured out of stainless steel or aluminum. The higher quality the materials, the less trouble you’re going to have in the long run, so it is always wise to check with the manufacturer first when buying a single-stage N₂O kit.

If there is such a thing as a heart and soul of a solenoid, it is the electric coil used to open and close the fuel orifice (see the illustration on page 14). Generally speaking, the coil is designed to operate at 20 percent of the maximum fuel operating pressure at WOT. The duty cycle of a high-pressure solenoid (which would always be the nitrous side) is generally no more than 30 seconds at 33 percent. Low-pressure solenoids (typically used on the fuel side) have a duty cycle duration of 5 seconds at 50-percent duty cycle.

Tuning Tips

Here are a few tuning tips that I’ve found to be useful over the years:

• Start with a realistic nitrous calibration recommended by the manufacturer.

• When you are comfortable with the recommended power level, increase power by providing more fuel and more N₂O to the engine through jet changes. At the first sign of detonation, backfire, or misfire, always reduce the size of the nitrous jets first.

• As you add N₂O (and thereby create more heat in the cylinder), pull back ignition timing. One general rule is to retard the timing at top dead center (TDC) until you experience a notable loss of power. Then kick it up a couple of degrees.

• An ignition retard box like one from MSD is highly recommended and functions as a safety valve.

• However, if you don’t have one of these boxes, set your ignition timing to a normal, non-nitrous setting so that your engine performs well when the N₂O system is turned off.

• After you have started with a properly adjusted carburetor, jetting should start on the rich side because it’s safer, and power levels are not as seriously affected nor are internal engine components as seriously taxed if coming from a rich condition rather than coming from a lean one.

• When adding nitrous oxide to a highly modified engine (i.e., big cam, high-compression pistons, ported and polished heads, headers, etc.), it is also safer to start on the rich side when tuning-in the system. Two jet sizes up from stock is considered being on the safe side.

• Of course there’s nothing like a good old-fashioned tune-and-test session down at the local drag strip to establish a creditable baseline. Again, start with a conservative jet size—perhaps one recommended by the nitrous kit manufacturer—and continue to tune your way up until you have achieved your fastest time.

• If in doubt, don’t be afraid to consult with some of the more successful nitrous racers who are running similar combinations, and keep a notebook of your progress.

• Caution: Do not make multiple changes to the engine, such as timing, valve lash, etc., while you are in the process of establishing a workable carburetor-tuning baseline. Make one change at a time to determine its effect and worth.

A solenoid is simply an electrically-activated on/off valve, which controls both fuel flow (gasoline or alcohol) and the flow of N2O at the flick of a switch. Some solenoids are manufactured of stainless-steel, and some from aluminum. Suffice it to say, the higher quality the materials, the less trouble you’re going to have in the long run, so it is always wise to check with the manufacturer before buying a single-stage N2O kit.

Amperage draw varies. Most single-stage kits feature 8.5- to 10-amp nitrous and 4-amp fuel solenoids, which combine for a system draw of 12 amps. But a higher amperage draw is going to allow the coil to open at a higher pressure. However, the longer a coil is open, the more amperage it draws, and the hotter it gets!

Orifice size is also very important because it dictates flow capacity. Think of a solenoid as a huge jet. You want the solenoid to flow at maximum PSI. In fact, its flow rating should always be larger than the combined metering jets throughout the rest of the fuel system.

Plunger quality and seal quality, which control the hit (or intensity) is also very important and has a lot to do with the longevity of the solenoid(s). Again, be sure to consult with your manufacturer of choice before selecting a kit. Remember, a bargain kit may not be such a bargain when you balance it against long-term component reliability.

Never use the wrong solenoid for an application. That is the quickest way to cause serious damage to an engine! Generally speaking, fuel and nitrous solenoid mounting brackets on a single-stage-plate N₂O kit typically have the fuel solenoid located at the left rear carburetor stud, in the general vicinity of the fuel supply line and the N₂O solenoid being located at the left front carburetor stud. Mounting brackets vary depending on the level of sophistication and cost of the kit in question. Of course, you can always upgrade. Just to cite one example, Edelbrock Nitrous’ optional CNC-machined Two-Solenoid Bracket(s) for square-flange Edelbrock Performer, Holley 4500, and Dominator carburetors are some of the nicest solenoid brackets I’ve seen.

Nitrous Oxide Systems’ non-adjustable Powershot N20 kit (PN 05001NOS) for the Holley flange, and Q-Jet–type spread-bore flange (PN 05004NOS) offer up to 125 hp at the touch of a button. Note that there is also a Powershot Universal kit application (PN 05000NOS). For those who want more power and controllability, there’s the 100-125-150-hp Super Powershot nitrous kits available in standard Holley 4V flange (PN 05101NOS), Q-Jet-type spread-bore flange (PN 05104NOS), and even a Holley 2300 2-barrel-flange application (PN 051056NOS).

The NOS 200- to 400-hp Big Shot Single Stage N2O system is geared toward the really serious street/strip enthusiast. Advertised as the World’s Most Powerful Single-Stage Plate Nitrous System, power output is adjustable in increments from 200 to 400 hp. Available kits include the standard Holley 4V-flange (PN 02101NOS) and Holley Dominator-flange (PN 02102NOS). Nitrous Oxide Systems also offers five Cheater Upgrade Kits to convert Sniper (Powershot, and Super Powershot single-plate single-stage N2O systems) to 200 to 400 hp!