The job of any power adder is to enable an engine to burn more fuel, and burning more fuel is the only way to make more power. To make power in an internal combustion engine there must be a proper ratio of fuel and air. It's the air portion of the ratio that nitrous affects.
Nitrous oxide is a molecule with two nitrogen atoms bonded to one oxygen atom. In the nitrous bottle and under pressure, nitrous is in liquid form. When it's released through the nozzle, it turns to gas. During combustion, the chemical bond of the molecule breaks, releasing the oxygen atom.
By weight, air is 23-percent oxygen while nitrous is 36-percent oxygen. So there's more oxygen present in the nitrous-enhanced combustion chamber ready to make power. When the proper amount of fuel is introduced and sparked, more power is made.
The advantages of nitrous carry much weight. First, it's universal in character. A nitrous kit can be installed on virtually any car, so even the red-headed stepchildren of the import scene that don't have huge aftermarket support can make power with the big dogs.
Second, nitrous hits hard everywhere but in the wallet. Basic single-nozzle dry systems for EFI cars can start between $400 and $500 with high-end systems topping out at $1,400. A typical single-nozzle system can generate up to 60 hp, or about $8.33 a pony. The more complex direct port or plate systems can pump out as much as 150 to 200 hp, or from $7 to $9 per horsepower; that's dirt cheap.
Third, today's nitrous kits are supremely tunable. Some of the more basic kits can be jetted from 25 to 150 or 200 hp. Of course, the enthusiast must be sure the engine can "kinetically" handle the power and the fuel system can provide enough fuel. Further, computerization is now part of the tuning equation. With this added precise control comes more power and more safety.
Some of the recent innovations in the nitrous oxide injection field include bottle heaters, remote bottle valve opening systems, staged injection nitrous systems, rpm-activated systems, fuel pressure cut-off strategies, injection via time, boost dependent injection and cabin-mounted pressure gauges.
In this series of tech articles, we'll examine a variety of kits from different manufacturers to illustrate the simple to the ultra high tech. We'll also illustrate innovations in delivery methods, tuning strategies, installation issues and safety.
First out of the gate is Nitrous Express' NXL system. This system won our Product Innovation Award at the 2002 SEMA Show. The NXL is a direct-port setup, which injects additional fuel and the nitrous at the injector site. The NXL has a revolutionary integrated fuel rail that houses the solenoids and connects to NXL injector adaptors via soft plastic lines.
This makes a tube bender obsolete and drastically cuts installation time, since the solenoids are already in place and ready to wire up. The nitrous and additional fuel are introduced at the injector adaptor, which also houses the stock injector. The injector adaptor slips over the injector and has its own O-ring system to ensure proper sealing. The interior of the adaptor has ports where the nitrous and fuel flow into the engine.
While the adaptor concept was introduced by NOS, Nitrous Express has designed the internal ports a little differently. Jetting swaps are made at the adaptor and Nitrous Express includes jet combinations that spray 40, 60 or 90 hp into the engine. Of prime concern to enthusiasts should be the engine's fuel system and the heartiness of the pistons and rods. The key isn't if you can make 90 more hp but whether or not the engine can take 90 more hp.
The strong points of the Nitrous Express NXL system are its integrated fuel rail design, premounted nitrous and fuel solenoids, use of flexible lines and its injector adaptor technology. The Nitrous Express fuel rail also offers a cosmetic upgrade. Many different anodized colors are available.
The NXL system is available for Honda B16 engines and Nitrous Express will be introducing a universal four-cylinder kit for imports as well as systems targeting Camaro, 'Vette and Mustang. The challenge is in the injector adaptor, which has to physically house the injector and meld with the intake manifold. It should be interesting to see how the universal kit addresses these issues. From the ease of installation and power output angle, the NXL system embodies virtues that power enthusiasts on a budget should embrace--getting more for less.
In many cases, the nitrous cylinder or bottle is the fashion statement of the kit. Usually positioned in the trunk, the bottle becomes the center of attention and it hits harder visually than underhood-mounted solenoids. Beyond color, the choice here is also one of materials.
Taking Nitrous Express as an example, the standard white bottle can be swapped in favor of a "The Fast and the Furious" bottle. For the weight conscious, Nitrous Express offers a carbon-composite bottle that tips the scales at 8 pounds compared to conventional examples that check in at 14.5 pounds.
It should be noted the composite bottle holds 12 pounds of nitrous, compared to the 10 pounds contained by the standard-issue bottles.
The downside is cost. Composite bottles go for anywhere between $400 and $600 or roughly $60 to $90 per pound of savings. These bottles are usually racer options, where weight is a super-critical issue. They are really cool, though.
|Manufacturer Nitrous Express|
|Style||Direct Port Wet|
|Engine||4-Cyl (Honda B-series)|
|Street Price||$928 - $1039|
|Nitrous Express NXL Jetting Table|
(Static Fuel Pressure 40 psi)