Making Big Nitrous Oxide Power In The Modern Pro Mod World

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The evolution of drag racing has been an on-going process since the first two cars lined up to race on earth. Ever since that day, racers have been trying to find ways to go faster and to outrun whomever they are lined up against. Part of the progression of racing has been the introduction of power adders, like turbochargers, superchargers, and nitrous oxide. Each of these systems brings something different to the table, and each has gone through extensive development over the decades in racing.

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Big horsepower nitrous systems like what you see in NHRA Pro Modified or the PDRA’s Pro Nitrous class are kings of the giggle juice world, and they’ve transformed into complex setups that are capable of producing hundreds of additional horsepower when lit.

Using nitrous oxide as a performance booster for an internal combustion engine first happened in war time. Military aircraft in World War I and II needed some extra power at times to allow them to gain speed and climb quicker in the sky, so they were equipped with the first nitrous systems to help give them that extra power.

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Like many other military technologies, nitrous found its way into the civilian world, and eventually — and naturally — racers were trying to use it at the track. Most didn’t understand early on how to use nitrous oxide correctly and tore up a lot of parts in the learning process, but those who did made big power with this magic substance. That breakthrough would aid in setting the stage for the birth of Pro Modified-style racing as we know it…and the racing world would never be the same.

Any engine is limited on the amount of power it can produce by how much oxygen it can pull in as it operates. Nitrous Oxide is a chemical compound that allows you to add more oxygen to the combustion process, therefore creating more power in the engine. So, for a big horsepower system, it becomes very important to flow as much nitrous oxide into the engine as possible; and the larger the engine, the more power it will produce on the juice.

Big Power Nitrous Systems Basics

Modern Pro Mod-type nitrous systems are made up of more or less the same parts no matter the method of fuel delivery. Components like nozzles, jets, lines, fittings, distribution blocks, and solenoids feed lines for all of the different systems that are still used today for the big-power nitrous kits. What’s different now versus 10 or 20 years ago is the level of complexity in these setups, along with how the fuel and nitrous are introduced into the engine.

Brandon Switzer and his company, Switzer Dynamics, specialize in anything related to induction systems and bringing nitrous into a motor for these higher horsepower applications. Switzer been designing these systems for many years and in that time he’s developed a broad understanding of what it takes to make them work at their full potential.

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The new generation Pro Mod nitrous systems are extremely technical, and as such, they’re able to produce more horsepower than ever.

“These Pro Mod cars are running five or six systems of nitrous with multiple, large solenoids pushing the nitrous into the motor. These are all direct port-type systems with the nozzles in the intake runners to deliver everything,” Switzer explains.

Wayne Davis, the General Manager at Speedtech, adds some additional details on just how these big nitrous setups work.

“On these systems, you have either a single circuit, two circuit, or three circuit nozzle that is a dry shot, and that depends on the manifold and application for each car. You will have all of your different lines and distribution blocks and the solenoids included with the system. The body of the solenoids that are used usually are now made of billet aluminum. This makes them lightweight and allows them to flow better on the big engines. Each system would have two of these big solenoids — one for the left bank and one for the right.”

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Fuel injection has taken over in the world of high horsepower nitrous applications in Pro Mod cars.

Fuel Injection Revolution

One of the biggest changes in the Pro Modified and Pro Nitrous ranks has been the move away from carburetion as a form of induction, and the implementation of fuel injection for the racers. This change has been going on for several years now, and has become the new normal for all of the top teams as they push their programs along to gain performance. As this change has occurred, it has shifted the process of what needs to be done in designing a big power nitrous system.

Carbureted systems (Left) are still used in some Pro Mod applications today, but are not as prevalent as the fuel injection systems (Right).

“For a Pro Mod team that wants to update their program to fuel injection, we get all of the dimensions of their engine and design a modern system around it. That would typically include the intake, nozzles, hard parts, solenoids, injection system, and the ECU. That’s what most companies do more of now, rather than selling parts and pieces. These big engines with five systems on them are very tricky and don’t have a lot of room for error in the nitrous system design process. Everything has to work together, or the customer won’t succeed and be happy,” Switzer says.

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Where fuel injection has changed the game is how everything is delivered inside the motor. These systems are now using a dry shot that delivers the nitrous into the engine via a direct port or fogger method. This is similar to what you see on street cars or smaller systems where the fuel is introduced separately from the nitrous, but on a much grander scale.

The fuel injection stuff is big and pretty much taking over the market for Pro Nitrous and NHRA Pro Mod cars, they’re all on it – Wayne Davis

To make sure the nitrous is delivered correctly, the best possible solenoids must be used. “Solenoids are made of billet aluminum on a CNC machine these days for more consistency and tighter tolerances. We’ve also changed the design a bit to allow for better flow with the port work,” Davis says.

“A Pro Mod or Pro Nitrous solenoid is all about efficiency, not the maximum flow, because it doesn’t have anything bigger than a .36-inch jet in each system, so you’re not taxing the max flow rate of the solenoid. It’s more about making sure the nitrous flows properly where it needs to go, and doesn’t phase change in the process,” Switzer adds.

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Solenoids, distribution blocks, hard lines, and nozzles still make up all high horsepower nitrous applications.

The reason a quality solenoid is so important is based on how one of these big horsepower systems operates as the car goes down the racetrack. Each nitrous system can flow nearly 500 horsepower worth of nitrous oxide, but that’s never done all at one time.

The solenoid must accurately control the flow of the nitrous so that the power can be brought in at different times by each of the separate nitrous systems for power management purposes. Throwing nearly 1,500 horsepower of nitrous to the track at one time might seem fun, but the car will never make a clean pass because it will overpower the racing surface.

On a fuel injected nitrous system, a small electronic fuel pump (Left) is used to prime the system. Due to the large demand for fuel, a mechanical pump like this Waterman unit (Right) is used in a Pro Mod nitrous system when it's equipped with a fuel injection system.

The use of fuel injection in these large nitrous systems on big cubic inch motors for Pro Mod-style racing requires strong fueling needs. Most racers use a mechanical-type pump with their fuel injection system since an electric pump cannot create the fuel pressure or volume required to correctly fuel the system.

“When designing the fuel injection system, you start with what will be the maximum output of the engine and then size the injectors and everything else around that to start,” Switzer says.

Fuel Injection Manifolds vs Carburetor Manifolds

Things have changed significantly with the new fuel injected manifolds, according to Switzer.

“The fuel injected manifolds are quite a bit different because now you’re only trying to distribute air. So, things you weren’t able to do with a carburetor manifold because it was air and fuel moving through the intake,  you can now do with fuel injected manifolds.”

Another part of the fuel injection system is the actual injectors themselves. The injectors are vital to a high-power nitrous system because they ensure the right amount of fuel is being delivered at the appropriate time.

“We see injector size vary from 175 pounds all the way up to 230 pounds or more depending on the application,” Davis explains. “With the dry shot like these Pro Mod cars use, the fuel is introduced via the injector above the nitrous in the intake when the system is activated. The fuel map in the ECU knows how much is needed to run on motor, then will introduce more fuel via the injector based on the amount of nitrous being sprayed at the time during the run.”

Keeping The Monster Happy

In the early days of Pro Modified racing, a 600 cubic inch engine was considered exotic and cutting edge. Now, racers are using engines that approach nearly 1,000 cubic inches in displacement. With these larger engines, more nitrous oxide can be added to the combustion process and that leads to a whole new set of problems for the health of the engine. A false move behind the keyboard can lead to an expensive and disastrous outcome on the track.

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Big motors need big systems to make the power required to run at the front in Pro Mod.

“The thing with these engines is that they’re so big now that they’re more susceptible to big air changes from race to race, and that will cause problems for them,” Switzer says. “These engines also tend to get much lazier when there’s more water in the air, due to their size, and that will affect the nitrous tune-up.

The Pro Nitrous and Pro Mod systems of today isn’t something an independent racer can buy parts for and develop a program themselves easily. – Brandon Switzer

“If you don’t make the proper changes based on what the air is doing track to track, you’ll burn it up, or just not run very good,” Switzer continues. “They take a bigger swing of changes than what the smaller engines used to, as well, when you make adjustments to keep them alive.”

Davis agrees with the idea that tuners play an even bigger role in keeping these big nitrous motors happy in the fuel injection era.

“With the fuel injection systems now, it’s more in the tuners hands to keep these engines where they like to be. Not detonating too much, not going too lean, and not being too fat play a bigger role with these giant motors and nitrous systems.In the world of Pro Nitrous and NHRA Pro Mod, these guys are pushing the cars so hard that you don’t have a big margin for error.”IMG_6203

The Future For Big Horsepower Nitrous

Just because nitrous oxide has become a mature technology, doesn’t mean that the limits of the technology have been reached. The development of fuel injection in conjunction with the use of the mountain motors has shown there is, in fact, a future of growth for nitrous, and the ceiling is much higher than what most think.

As teams learn to use the fuel injection systems more, and find the limits of what can be done, gains will be seen on the track. Racers in the Pro Mod ranks must also learn how the bigger motors like to be fed the nitrous, and how to use the fuel injection with these massive displacement mills, as well.

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Looking into the Speedtech crystal ball, Davis sees a future where everything must work together for the gains to be significant.

“Fuel injection is really the next big thing where the gains will come. All of the tuners, engine builders, and nitrous companies are starting to get their mind around how it works. The motor, nitrous, and fuel injection systems all need to work together to be as efficient as possible to maximize the gains. The chassis guys will also need to make some adjustments so the nitrous cars can use all the power that will be available,” Davis explains.

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There are some other things on the horizon, according to Switzer, that might surprise some in the industry.

“The mechanical gains of this combination are going to continue, but they’re big projects, very expensive and will be for small gains. The biggest gains will be on the electronics side of things. One of the largest gains will be going into direct injection. You’re not putting fuel into the intake manifold; it will drive up efficiency and power output. It’s not around the corner. It’s five years down the road, but that will be the next big thing, for sure,” he says.

In conclusion, making big power with nitrous oxide has never been an easy task, and it’s now infinitely more complex with modern technology. To run at the front of the pack in Pro Modified or Pro Nitrous, a racer must embrace new ideas and soak up any and all knowledge and data they can.

Pro Mod racers continue to push the boundaries of what nitrous oxide is capable of, and find new ways to advance the power adders’ potency further to become quicker at the track. The possibility for even quicker elapsed times is just around the corner, as tuners begin to understand how to make all the new breakthroughs work together, one purge of nitrous at a time.

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About the author

Brian Wagner

Spending his childhood at different race tracks around Ohio with his family’s 1967 Nova, Brian developed a true love for drag racing. Brian enjoys anything loud, fast, and fun.
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