CUSTOM DUAL-STAGE DRY NITROUS SYSTEM
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My dual-stage dry N2O kit is a very simple derivative of NOS's 5177 kit. The 5177 kit is easily transformed into a dual stage system for less than $100.00 (this assumes that you are already operating your 5177 kit with an RPM activated window switch; if not, you will need to add one in addition to a second RPM activated switch). The following will describe what parts and steps were necessary for me to perform this mod.
Why dual stage? I wanted to be able to run a lager shot of nitrous, but I didn't want to spray a big shot right off the line due to traction issues. Also, I didn't want to spray a large amount of nitrous into the motor at such a low RPM. As engine RPM increases, so does its ability to handle a lager shot of nitrous. At low RPMs the valves are being held open for a longer period of time, which allows for more nitrous to fill the cylinders. This leads to extremely high cylinder pressure (which builds heat) and can quickly lead to detonation and/or blown head gaskets. That being said, here is what I came up with:
Below is how my system was originally wired in its intended, single-stage configuration. The section to the left of the diagram is a blow-up of the back side of the NX switch panel. The grey portion to the right is a rough depiction of the engine compartment and underside of the dash. The far right of the diagram is representative of the front of the car and the left portion of the grey represents the underside of the dash (where the MSD window switch is located). When wired in this manner, the RPM activated window switch receives power when the system is armed by flipping on the arming switch. When the desired RPM is achieved (depending on what pills are installed in the window switch), the RPM activated switch, in series with the wide open throttle (WOT) switch, provide a ground to the relay. The relay, when provided with a ground, provides 12V of power to both solenoids. One solenoid is grounded to the chassis, so it always opens when provided with power from the relay. The second "safety" solenoid receives its power from the relay, but gets its ground from the fuel pressure safety switch (FPSS), only when there is adequate fuel pressure to complete its circuit. If there is not, the safety switch will not provide a ground to the safety solenoid and it will not open. Nitrous will not be injected into your engine until the fuel pressure is adequate.
(Click on diagram for a larger view)
To operate your system as a dual-stage one, you must reconfigure both how your system is wired and how it is plumbed. This may become confusing, so refer often to the diagram shown below. Notice that the RPM activated window switch and WOT switch are now wired inline with the fuel pressure safety switch (FPSS). Previously, the FPSS provided a separate ground to the safety solenoid. Now, they all three provide a ground to the relay. The first stage solenoid is already grounded to the chassis. The first stage is activated as soon as it receives power from the relay. The second stage solenoid receives its power the same time the first stage solenoid does, but it is not activated because it has no ground. Its ground is provided by a second RPM activated switch (does not need to be a "window" switch). at the desired, higher RPM. When the "high RPM" setting in the first stage window switch is achieved, both stages will be deactivated. This is because the ground is being cut off from the relay, and the relay will pull the 12V power from both solenoids.
Now for the plumbing. The four labeled fittings in the diagram are NOT provided in your 5177 kit and must be purchased. You will no longer be using the the 1/8 NPT to 3AN 90* elbow or the 3AN male to 3AN female tee fitting that were provided with your kit. Once again, refer to the diagram when this gets too confusing. In the stock configuration, the solenoids are mounted inline so that nitrous flows from one solenoid in to the next. You will need to flip one solenoid in the opposite direction, so that the "in" side of both noids face in and the "out" side of the noids face out. The block that originally connected the two noids together will still serve the same purpose, but the 1/8 NPT plug in it will be removed and replaced with the 1/8 NPT to 4AN fitting that was previously installed in the inlet side of your first solenoid. You will then install the plug into the 4AN male to 4AN female N2O gauge adapter (see diagram), and install the adapter on the 4AN fitting (see diagram). Now, attach the 4AN male to 4AN female 90* elbow to the bottom of the gauge adapter. Next, install the 3AN male to 1/8 NPT male fittings into the outlet side of both noids. You can now reattach the noid configuration to the mounting bracket. Your noids may now be slightly further apart, so it may be necessary to extend the mounting holes on the bracket so they line up with the mounting holes on the noids. Once you remount your noids, you can attach the 4AN main feed line to the 90* elbow and attach the 3AN feed lines (that go to your air box) to the outlet sides of your noids. Note that the hole in that you plugged in the gauge adapter can easily be used later to plumb in a purge.
(Click on diagram for a larger view)
