Nitrous can boost your engine’s power output, but you need to follow its rules
If you’re wondering what’s the easiest and cheapest way to add a lot of horsepower to your engine, then we have the answer: nitrous oxide. Yep, for less than $500 you can add 100 to 200 hp to your engine using common hand tools and without breaking a sweat. And unlike a cam swap, you don’t even need to bust into your engine. Of course, like all good things in life, there’s a caveat: You need to follow the nitrous rules if you want to go fast and avoid turning your engine into a lawn decoration.
How Does Nitrous Work?
Nitrous oxide (also known as dinitrogen monoxide or dinitrogen oxide in geek speak) works by introducing extra oxygen into the intake charge. You see, at 570 degrees F the oxygen breaks free and is added to the combustion process. This allows for a greater amount of fuel to be added and converted into energy. All of this greatly increases the power output of the engine. Another benefit is that because nitrous oxide is stored as a liquid, the evaporation of it in the intake manifold helps drop the intake charge temperature. This cooling causes a denser charge and can increase power output, as well as reduce detonation. Oh, and in case you’re wondering, “Why not just inject pure O2?” Well, unlike O2, NO2 isn’t flammable at room temperature and when not under extreme pressure, so it’s considerably safer than O2.
What Are The Dangers Of Nitrous (NO2)?
Like everything in life that sounds perfect, there’s a cost involved. With nitrous the cost is vigilance. When using nitrous you have to be very careful with bottle pressure, fuel pressure, timing, and a host of other things. If all is set up right, then it’s a beautiful thing; if not then a fragged engine and tears looms on the horizon.
As nitrous is used, the pressure in the bottle drops, so less nitrous is forced out under pressure when the switch is flipped. If this isn’t accounted for, then there will be less nitrous introduced, and because the fuel side the equation is still fine, the result is a rich condition. This is better than a damage-causing lean condition, but it’s not better for making power. For this reason many people opt for using a bottle heater. The heater warms the bottle, which increases the pressure to keep the flow consistent. These days companies like Zex and NOS offer ways to safely heat your bottle so that you won’t accidentally flip the switch and warm a full bottle to the point where, in spectacular fashion, it blows the safety valve.
Other factors are having adequate fuel supply to ensure you don’t go dangerously lean and making sure to knock out some timing, typically around 4 degrees, to keep everything happy. Study up and follow the well-established rules, and nitrous can give you many hits without any drama.
What nitrous system is best for my car?
Well, that’s the hundred thousand dollar question. The answer is that there are many great systems on the market that will work on just about any engine you might have, from big-blocks with carbs to modern EFI LS and Vortech mills. Companies have been working hard to come up with new ideas to deliver consistent nitrous shots to engines. After all, it takes a fair bit of engineering to make sure the same amount of fuel and nitrous is delivered, equally, to all of the cylinders. Here are a few of the types on the market. We’ll skip direct-port kits because if you’re going that route, you most likely already know all of this. Also, these are all “wet” kits, which means the kit adds nitrous (the dry part) along with fuel (the wet part). Dry systems rely on the engine’s fuel injectors to add the additional fuel to the equation and are not used at all in carburetor applications. Dry systems typically use a single nozzle to deliver the NO2 to the intake tract and will require hacking into your car’s ECU.
Single- and dual-bar plate systems
These are the most commonly seen plates out there. In short, nitrous enters one side and fuel the other, both controlled by solenoids and regulated by various-sized jets. The atomized NO2 and fuel is disbursed by the bars into the intake plenum, below the carburetor or throttle body, and into the engine. In most cases these support 100 to 150hp. Complete kits can be found for less than $500.
Perimeter plate systems
This system uses a billet plate to atomize the NO2 and fuel, which is then fogged into the intake plenum, as the name implies, around the entire perimeter of the plate (12 points of discharge on this Zex plate). In theory this helps ensure the same amount hits each cylinder. These kits are a bit more expensive (a bit under $700), but ones such as this example from Zex can support nitrous hits of 100 to 300hp. On nice benefit of this system is that the plate itself acts as a cooling mechanism, hitting temps way below freezing, between the carb/throttle body and intake. Gotta love science!
Cross-bar plate systems
Less common would be a cross-bar plate system. This CrossHair kit from Holley is more expensive than the other offerings, but it can supply from 250hp to over 350hp more to your engine! Again, delivering nitrous is all about distribution and atomization, and according to NOS this design delivers on both single- and dual-plane intakes, though for bigger hits of nitrous, single-plane intakes are the way to go. On this system both the fuel and nitrous circuits employ two separate bars, one running fore and aft, the other crosses at 90 degrees, left to right. There are two jets required for the nitrous circuit, one for each bar, and likewise, two jets for the fuel.
EFI throttle body wet plate system
Have a modern mill with a factory-style throttle body? Well, you’re in luck because adding nitrous is just as cheap and effective. Plates such as this LS-style example from NOS can deliver from 75 to 250hp to the wheels of your modern engine–equipped ride. Because the plate is only ¼-inch thick, it slides in easily between the throttle body and the intake without hassle. Just like the systems above, these kits start at under 500 bucks.
How much nitrous is too much?
Typically you can safely add 70—150hp shots to most any healthy engine. After these levels you need to take more steps to ensure a happy engine. Larger shots of nitrous requires “advanced measures” such as specific ring gaps, modified timing tables, forged internals, and even having the nitrous come on in stages to keep from blowing the tires into spectacular clouds of smoke.
Sure, getting into nitrous is pretty cheap, but from there you can spend as much as you want and go as fast as you can afford. Advanced-level widgets like this two-stage progressive nitrous controller will let you supply, and more importantly control, all the nitrous you heart desires. Electronics like this let you feed in nitrous slowly over a course of time so that it doesn’t all hit at once. When you reach this level, you need have your ducks fully lined up and doing your performance bidding.
Other options, besides nitrous pressure gauges and heaters, include bottle blankets, blowdown tubes (required at some tracks), and purge kits. Purge kits let you dump the warm nitrous in the line right before use so that you get the added cryo effects of a fresh hit of NO2. An added bonus is that it looks cool.
How hard is nitrous to install?
The entry-level kits we’ve discussed are very easy to install. Yeah, there’s basic wiring involved, but all the big companies provide nearly idiot-proof instructions and wiring diagrams so you can start making more power without even working up a sweat.
Many of the kits, like this NOS Sniper system for an LS3 engine with a larger throttle body, come complete with everything you need. Of course, you can add options like purge kits, gauges, and bottle warmers as your budget allows.
What does a nitrous hit look like?
A nitrous hit is a fairly all-at-once and somewhat violent deal. Without a progressive controller, the hit you choose happens in a blink of the eye. The graph above is a ZZ454 Chevrolet crate engine with the NOS Crosshair Professional Plate system. This was a 250hp shot, and for this large shot 10 degrees were pulled out. You can imagine what a sudden bump in power like this would feel like in a car, which is why multistage and progressive controllers are a good idea for larger shots.
Can you run nitrous on a stock engine?
Yep, in fact we recently did this on a bone-stock 4.8L Vortech engine from a junkyard and safely picked up over 100hp! When you combine the low cost of a nitrous kit with the dirt-cheap prices on salvaged LS variants, the result is a lot of cheap fun!
Why nitrous oxide NO2 is the cheapest and easiest way to add power to your engine:
- Complete kits can be bought for less than $500
- Basic plate systems are easy to install
- Nitrous plate systems don’t require tearing into an engine and can be easily removed.
- Easy to add anywhere from 75hp to over 250hp to your engine
- Safe as long as you follow the rules
- Nitrous is easy to upgrade over time with options like bottle warmers, purge systems, and gauges
- Traction can be controlled on larger hits of nitrous by using progressive and staged controllers
- Smaller shots are perfectly safe, if done correctly, even on stock engine with cast or hypereutectic pistons.
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