Ultimate NOS 05115 Dry thread
As much as I regret to do this, I am going to take down my project website on mustang nitrous. This is after a general lack of support from many of the big name nitrous companies. With that said, I didnt want all the info I worked on to go to waste. I compiled a TON of info on the NOS dry 05115 kit. Enjoy.
As the advent of fuel injection set upon the automotive industry several changes began to take place. Carbureted intake manifolds were designed from the ground up to flow not only air, but fuel as well. This meant that carbureted nitrous systems had no major drawback by simply throwing fuel, and nitrous down the intake manifold to achieve the desired horsepower. Sequential EFI on the other hand, posed a slight challenge. EFI intakes are designed to only flow air, as the fuel is added just before the intake port of the head. While some people were having mixed results making their little EFI mills chug nitrous via a wet kit, NOS had a better idea. If there were some way to let the injectors add the extra fuel, by just spraying nitrous by itself down the EFI intake it will allow the intake to operate as it was designed to with a dry intake charge.
There are only two ways to do this on an EFI vehicle. The first is to increase the fuel pressure, and the second is to increase the pulse width, or time that the fuel injectors are open. Since EFI fuel pressure regulators work on a 1:1 ratio with fuel and boost, or air pressure, increasing fuel pressure seemed like the logical approach. By placing 1 lb of boost on the vacuum line to the fuel pressure regulator, fuel pressure will be raised by 1 PSI. With this method, once it was determined just how much fuel pressure would be needed for a given nitrous shot size, pressure could be placed on the fuel pressure regulator to make it reach that particular point. Nitrous oxide is typically at 900-1000 PSI in the bottle. Naturally this would be far too much pressure to place on a fuel pressure regulator and would instantly burst the diaphragm inside the regulator. Since 1987 NOS had been hard at work on a device to get 1000 PSI down to a more usable 50 PSI. The device is little more than a mechanical servo unit.
While working at NOS, Mike Nelson soon saw the potential a setup like this could have and went to work perfecting the dry kit. Unlike many generic wet kits, the NOS-05115 actually began life from the ground up as a 5.0 Mustang specific kit. Once the regulator was in place it was realized that for adjustability, a bleed off tee must be incorporated. The bleed off tee basically serves no other function than to control the amount of pressure being placed on the fuel pressure regulator. A larger jet will yield more bleed off, and thereby less fuel pressure, while a smaller jet would create less bleed off, more pressure on the fuel regulator and ultimately more fuel. This makes the fuel or nitrous tee side of the jetting exactly opposite of a normal wet nitrous kit. Bigger jets supply less fuel while smaller jet sizes supply more fuel.
Now that the fuel side was ironed out, the only thing left to do was inject the nitrous oxide into the intake tract. Of course NOS went above and beyond by installing a vital safety feature in this kit. The NOS-05115 uses not one, but two nitrous solenoids. As the nitrous system is activated, the first solenoid opens up and begins flowing nitrous through the nitrous regulator. As the fuel pressure begins to spike, it triggers a "hobbs" or fuel pressure switch at about 55 PSI. This switch then activates the second solenoid which allows nitrous to flow through the nozzle and into the intake tract. The fact that the second solenoid simply cannot function without fuel pressure at or above 55 PSI makes this kit the safest kit on the market to use. As an added benefit, since the fuel pressure is raised and then nitrous is injected into the intake manifold independent of each other your engine starts out running rich, and is then leaned out by the induced nitrous oxide. A wet kit many times will go from lean to rich as a result of a few factors, the first being that when the fuel solenoid is opened it basically acts as a hole in the fuel system and momentarily drops fuel pressure a bit. The second reason is that fuel pressure is generally 40 PSI and nitrous should be 1000. As the two solenoids open in a wet kit, the nitrous usually wins the drag race and is injected slightly before the fuel. Some wet kit users raise fuel pressure and/or place a longer line to the nitrous nozzle to try and combat these ill effects.
Probably the safest feature of any dry kit is that you simply do not mess with raw fuel. Instead of running aftermarket fuel lines you let the OEM fuel system handle the vital job of injecting fuel. There is no need to tap into your fuel system for anything other than a place to mount your fuel pressure switch; although a fuel pressure guage you can see from your seat is a great idea. There is no need to worry about a fuel solenoid malfunction causing your nitrous injection to go lean, or worse yet activate without the nitrous causing a fuel puddle in your manifold. As a personal experience, the latter example burnt one of my cars to the ground and is what initially drew me to dry nitrous injection.
Because the nitrous regulator and the main nitrous feed nozzle are both fed from the same bottle, yet another benefit of this kit is realized. As your bottle pressure decreases the amount of fuel injected decreases proportionately to the amount of nitrous injected. Regardless of what Zex nitrous claims, this makes the NOS dry kit the first system to "tune itself" based on bottle pressure. Since its début a few years ago, many people have disasembled the lavender "control unit" to the Zex dry system and find nothing more than a single nitrous solenoid attached to a nitrous distribution block. As the nitrous block is put under pressure, a non-adjustable bleed hole feeds nitrous to your fuel pressure regulator. By using the same basic principals of the NOS-05115 kit Zex has simply placed a much more primitive system in a dressier self contained package. Aside from the inability to tune the fuel pressure with this kit, there are two more major draw backs with this system. Since the Zex system lacks a nitrous regulator like NOS kit uses, the initial fuel pressure spike is very high and can damage your stock fuel system. Initial pressure spikes as high as 125 PSI have been measured with this kit. The worst feature of this kit, and perhaps the most ironic as Zex claims to be "The Worlds Safest Nitrous System" is the lack of a pressure safety switch. Without this switch in place, as soon as the nitrous pressure is sent to your fuel pressure regulator it is simultaneously released through the nozzle into your intake. There is no delay for the fuel pressure to rise, or confirmation that the fuel pressure has risen to safe levels. The nitrous oxide is just injected into your intake tract on blind faith.
Since the introduction of the 5115 kit, it has gone from a simple 75 HP pick me up to a fully adjustable 75-150 HP system. The mustang crowd has been using this system for years with great results. After the principals of this kit were understood, it didn't take long for some guys to throw in larger fuel injectors and start running some really big nitrous shots. The small nitrous solenoids supplied with the kit and the tee that connects them will only support about 175 HP worth of nitrous. Upgrade your fuel injectors, nitrous solenoids and connection tee and you are knocking on 200 HP with proper jetting. The -3 nitrous nozzle line, the nitrous nozzle itself and even the -4 feed lines start standing in the way of power production shortly there after, but with modifications or upgrades, the sky is the limit with this kit. On the west coast a select few were throwing huge injectors on their cars with these hybrid kits and making insane power. Mike Nelson recalls customers using this method to make so much power that they were literally tearing the hides off their tires at 50 MPH in 4th gear on the highway with their daily driven street Mustangs. It is no surprise that this is the method Mike suggested to NMRA Real Street competitor Bruce Hemminger when he called Mike for advice after getting frustrated from nitrous backfires with his wet setup. This setup soon proved to be the method for reliable big nitrous shots through a single nozzle and all other nitrous competitors in this class soon followed suit. Since the late 80's methods of altering the stock mustang computer have came a long way. Instead of using the trusty NOS nitrous regulator to increase fuel pressure, many racers now rely on programming to increase the injector pulse width under nitrous use with these huge kits. This has been so successful that Anderson Ford Motorsport now markets dry kits capable of over 400 HP using this method with their PMS engine management.
It is important to note the drawbacks of this kit , even though they are few and far between. Since the kit increases fuel pressure to to add more fuel, some people have had the rubber line that connects the two fuel rails together rupture under this pressure. This phenomenon seems to be exception rather than the norm. The biggest drawback with a dry system is the fuel and nitrous mixture itself. Since stock fuel injectors with elevated pressure are used to supply the fuel, the ammount of fuel is nearly identical from cylinder to cylinder. EFI intake manifolds, and ford manifolds in particular are notorious for uneven distribution of air. Since the nitrous and fuel dont combine until they are actually entering the cylinder head, this causes an uneven mixture to enter each cylinder causing some cylinders to run rich while others go slightly lean. For street applications you will not notice this and the variations will be so small that they arent worth mentioning, but on bigger shots distribution can be a problem with these kits. Dry kits also do not "hit" as hard as wet kits initially because they start rich and allow the nitrous to lean out the mixture. This can sometimes be an advantage, however, as traction will be severely limited in most instances on nitrous oxide.
The NOS-05115 dry kit has proven its worth for over a decade now. From illegal street racing folklore to nationally sanctioned events it is by far the safest, and most potent way to give your mustang nitrous injection. At home on a daily driven street car or a 650 HP race car, the principals behind this kit have been imitated time and time again. A cult icon, and a legend in the making this little NOS kit is just as popular now as when it was first released. Up to 150 HP the ultra safe kit works perfectly, and this makes it a simple and effective choice for your daily driven mustang.
Last edited by Supernatural; 04-07-2006 at 07:59 AM.