by Jon Mikelonis

Introduction
Nitrous Oxide (N20) isn't for everyone and during my first nitrous install, I wasn't sure it was for me either. Afterall, I don't race nor do I have any near term plans to increase my amount of wide-open-throttle street driving. Nonetheless, I still enjoy getting familiar with performance items and gaining technical experience like most of the FordMuscle community. But most of all, as it relates to writing for FordMuscle, I have a passion for demystifying the seemingly complex, overly technical, or ultra-intimidating. In this article, I will take you step-by-step through a carbureted Nitrous install in order to help you decide if hitting the bottle is right for you.

	Feature car flicks like Stallone's Cobra sometimes portray Nitrous Oxide systems as very rudimentary "flip-of-the-switch" sources of high horsepower. If you have never installed a N20 system, you'll soon find out that a proper system goes beyond a basic dash mounted toggle switch, solenoids, and bottle.

Whether it was Stallone in Cobra or Mel Gibson in Mad Max, there has always been an allure for car guys to the concept of flipping a switch for an instantaneous high increase in horsepower. However, Hollywood's use of creative freedom for cinematic impact has lead to many misconceptions about Nitrous Oxide as well as creating high expectations for the enthusiast. With that said, going into my very first nitrous install, I was sure to lower my own expectations and accept a fair level of troubleshooting before realizing any immediate power gains from my 460 powered 73 Torino.

For background information on the science of Nitrous Oxide be sure to read the first page of FordMuscle's article Bottle Feeding. In addition to that article, here are three additional facts that will prepare you for reading the install and pictorials to follow on the next four pages.

In the most basic form, a proper Nitrous Oxide system uses three "switches" to introduce N20 into your intake charge; a primary interior mounted "arming" switch, a wide-open-throttle (WOT) switch, and a RPM window switch. This mini network of switches should erase any notion you may have that the flip of one single switch will instantly peg your tachometer.

Modern nitrous kits and aftermarket ignitions have greatly increased the ability to control the timing, amount, and duration of the "shot", making nitrous safe for OE motors and yourself when "programmed" and installed correctly. In other words, you don't need a bullet proof bottom end for nitrous if you correctly design a 100HP nitrous system.

Common problems with nitrous are insufficient fuel pressure, poor bottle temperature control, running too much timing, and activating nitrous at too low of an RPM.

For a good overview of common myths and misconceptions regarding nitrous, the article N2O Myths at Competition Plus is also recommended.

	Micro WOT Switch Most nitrous kits include a interior arming toggle switch and a micro wide-open-throttle switch. While this is enough to make a nitrous system function, including the third parameter of an RPM window switch will make a N20 system proper and safe.

Ignition Considerations and Installation
Nitrous Oxide systems are designed for use at wide-open-throttle. N20 Kits include a micro WOT switch that is mechanically activated by your throttle linkage. Installed and positioned correctly, this switch ensures that when the system is armed, via an interior toggle switch, the nitrous shot is only introduced at WOT. However, a proper Nitrous Oxide system doesn't stop there. In order to protect your motor and yourself, it's important that Nitrous Oxide is not only used at WOT, but also at a predetermined RPM range above 3000 RPM. The added measure of RPM range activation, prevents the Nitrous shot from being introduced into a low velocity air/fuel charge which can wreak havoc on your motor.

Combine the need to "program" this RPM range into your system with the
general rule of retarding your ignition timing by 2 degrees for each 50HP
shot of nitrous, and you'll need an ignition controller (MSD or Mallory)
to safely run Nitrous on a carbureted application. The MSD Digital
Programmable 6AL-2 and the Mallory HyFire 6.6 Multi-Strike CD Ignition are two market offerings that will get the job done as single units. There are many manufacturers of accessory RPM window switches that can be tied into standard CD ignition boxes like the MSD 6AL or Mallory HyFire 6AL.

In the simplest form, an ignition controller serves two purposes for a Nitrous Oxide application:

Determines what RPM range to activate and deactivate the Nitrous Oxide during WOT

Determines the amount to retard the ignition timing throughout the programmed RPM range

Wiring Schematic for Mallory HyFire 6.6 Multi-Strike CD Ignition
(click image to enlarge)


With that said, before getting involved with choosing or installing a
nitrous system, our carbureted 460 Ford application would need an ignition controller to satisfy 1 and 2 above. We took on installing, tuning, and testing a Mallory HyFire 6.6 CD Ignition Controller. It was important to work out any bugs and make sure the new ignition system was functioning properly before installing the Nitrous system. This ignition controller runs for about $420.00.

Here's the install:

This is the Mallory HyFire 6.6 straight out of the box. This ignition allows for rev limiting and also has a start retard feature. However, what I was really after was the programmable RPM window switch that allows you to program a predetermined RPM range for engaging the nitrous.		I used a Mallory Comp 9000 billet magnetic breakerless distributor to work with the HyFire 6.6. They come from the manufacturer with 24 degrees of mechanical advance at 3200 RPM. Wiring it all up does takes care and a moderate amount of effort.
The leftside 4 pin connector holds the positive and negative coil wires (yellow and black) as well as two wires bound for the distributor (red and green). I planned to mount the HyFire box on the passenger side floor board.		Here I am routing the four previously mentioned wires through a grommet and through the firewall.
Next, I fed the wires from the leftside 2 pin connector through the firewall. The red wire on the 2 pin connector was for 12V constant battery power and the black was for ground.		I hooked up the black and yellow wires from the 4 pin HyFire connector to the coil. Note: I was simply going for a preliminary install to verify operation before mounting the HyFire box and coil and performing final wiring.
Mallory includes these ring terminals (red circular piece) for easy wiring, they worked nice for preliminary test wiring but I eventually replaced them. Here I am connecting the red wire from the HyFire 4 pin connector to the 12V Key On wire that runs to the distributor.		The green wire from the HyFire 4 pin connector connects directly to the distributor. Again, I used another provided ring terminal.
I connected the red wire from the HyFire 2 pin connector directly to the positive side of the starter solenoid. I found a good ground on the engine block for the black wire from the HyFire 2 pin connector.		Next, I fired up the motor and set my initial timing to 12 degrees and verified I had 36 degrees at 3200 RPM. A good starting point.
I finish mounted the HyFire Box...		...and cleaned up the engine bay wiring.
The HyFire 6.6 includes a controller and serial cable. It does not need to be connected all the time.		At this point there wasn't much to program other than the rev limit and start retard. 12 degrees of initial timing never made for hard starting with my car but I experimented with start retard. Didn't make much difference for my application but would for high compression motors running a lot of initial timing. I set the rev limit to 6250 RPM.

(Nitrous Bottle Mounting, Main Line Install, and Bottle Heater Install)