Words And Photos: Richard Holdener

When it comes to power adders, there are two kinds-regular boost from a blower or turbo and boost in a bottle. Of course our reference to boost in a bottle is none other than that amazing substance known as nitrous oxide. If you are unfamiliar with nitrous oxide, the very first thing you should know is that you owe it to yourself to try it, at least once. Like any powerful, addictive substance, once you try it, chances are good that you’ll be hooked. What makes nitrous so cool and puts it so high on the must-try list you ask? How do you feel about having an extra 100 horsepower (or more) literally at the push of a button? Worried that your stock motor won’t stand up to the extra power? What if we told you that, in addition to adding power, nitrous doesn’t care what kind of motor you have? The amazing push-button power can be applied to just about ANY combination, from moped to mountain motor. Nitrous isn’t brand loyal, and could care less whether you drive a Ford, Chevy, or Dodge (or even import). In this online era of instant gratification, no other performance upgrade even comes close.

Before adding power to our small block, the charismatic chemical compound deserves a closer look. We know this goes against every thing you’ve learned online and in the movies, but the compound nitrous oxide is not explosive and, in fact, is not even flammable. That’s right, depiction of those spectacular fireballs on film require no less than the special effects team and a backpack full of C4. The reason for this is that, unlike gasoline, nitrous oxide is an oxidizing agent and not a fuel. While capable of greatly increasing the power output of your motor when combined with the necessary additional fuel, your engine will not run on nitrous oxide alone. By the same token, touching a match (or even a torch) to the stream of nitrous oxide will result in little more than said flame being unceremoniously extinguished. This amazing substance was first obtained back in the 1700’s then used as an anesthetic starting in the 1800s. Nitrous technology really came to the forefront during World War II, where it was used by both the British and Germans to enhance to power and altitude of their piston-powered (pre jet) war planes.

The key to the successful use of nitrous oxide is the liberation of the available oxygen molecule in the dinitrogen monoxide compound (the O in the N2O). Release of the power-producing oxygen molecules requires heating the compound to approximately 572 degrees, a temperature easily achieved during the combustion process of an internal combustion engine. Once liberated, the oxygen molecules are free to enhance burning of the additional fuel supplied and viola, instant power adder. As if the added power wasn’t enough, nitrous oxide comes stored in liquid form but is injected into the motor as a gas. As we all know, the process of turning from a liquid state to a gas is called vaporization (boiling). As luck would have it, the boiling point of nitrous oxide is a chilly -129 degrees. Injection of anything that cold into your motor significantly decreases the surrounding inlet air temp. This drop in charge temperature can both increase power and reduce the possibility of harmful detonation. Dinitrogen Monoxide FTW!

With a brief technical explanation of nitrous oxide now complete, let’s examine the specifics of the ZEX Perimeter Plate system we applied to our 350 test mule. According to experts at ZEX (does that make them ZEXperts?), the Perimeter Plate configuration offered a trio of beneficial design features including Perimeter Injection, Cryo-Sync and Airflow Enhancement Technology. Given that our V8 was made up of eight different cylinders working in unison, it was critical to have even nitrous flow to all of the individual cylinders. Unlike the common single, wet-fogger systems generally employed on EFI applications or the spray-bar system on a carbureted motor, the Perimeter Injection was designed to enhance cylinder-to-cylinder distribution.

Sandwiched between the carburetor and intake manifold, the ZEX plate system employed 12 (equidistant) injection points that combined nitrous and fuel to optimize both atomization (very important) and distribution. Thanks to the injection of a substance at -129 degrees, the nitrous plate itself works as a Cryo-Sync (or heat isolator) to help cool both the intake and carburetor. Rounding out the trio of benefits, the high-pressure burst of nitrous (and fuel) into the intake manifold worked to create a low-pressure zone to further enhance airflow into the motor. On paper at least, the design features offered by the Perimeter Plate power adder sounded impressive, but only the dyno would show for sure.

Our test motor started out life as a simple Vortec 350 pulled from the engine bay of a ¾-ton truck. The late-model, small block featured a four-bolt main block, factory hydraulic-roller cam and iron Vortec heads, but even decked out from the factory, the (high-mileage) stock motor (run with headers, a dual-plane intake and Holley carb) managed just 298 horsepower. In preparation for our liquid power adder, we enhanced the power output of the small block while maintaining the factory short block. We chose this route to illustrate both that the extra power offered by the ZEX perimeter plate was irrespective of the original power output (but more is always better) and that nitrous can safely be used with stock internals. The upgrades to the small block included a set of 200cc, as-cast, RHS aluminum heads, a COMP XR282HR Xtreme Energy cam and Edelbrock RPM Air Gap intake. Also part of the upgrade was a Holley 750 Ultra XP carburetor and MSD billet distributor. The head swap also necessitated a set of COMP 1.5 ratio High Energy (Die Cast) roller rockers.

Equipped with the new RHS heads, COMP cam and Edelbrock/Holley induction system, the power output of the junkyard small block jumped to 395 hp and 393 lb-ft of torque. The heads and cam netted almost 100 extra horsepower, since the baseline test was run with the Edelbrock/Holley induction already equipped. After running the baseline test, we installed the ZEX Perimeter Plate nitrous system with amazing results. We installed jetting (62N/53F) to provide an additional 150 horsepower. In preparation for the nitrous, the ignition timing was retarded by 6 degrees. Once we activated the nitrous, the injected small block belted out 546 hp and 541 lb-ft of torque. Had we activated it earlier in the rev range, the peak torque numbers would be even higher, but care must be taken not to get too greedy with early activation. Run properly, this power level can be enjoyed bottle after bottle and rest assured this nitrous small block will surprise some pretty fancy (high-priced) modern machinery. Power Adders Rule!

To ensure proper nitrous flow through the system, we made sure to heat the bottle (to 92 degrees) until the pressure gauge exceeded 900 psi.

As is evident by the graph, the ZEX Perimeter Plate nitrous system offered some serious power to our modified junkyard small block. Thanks to the RHS aluminum heads and COMP Xtreme Energy cam, the junkyard Vortec small block pumped out 395 hp and 393 lb-ft of torque. After installation of the ZEX Perimeter Plate nitrous kit, the peak numbers jumped to 545 hp and 541 lb-ft of torque. Equipped with the 150-hp jetting, the ZEX kit added exactly 150 horsepower to our small block. Of course we made sure to properly heat the nitrous bottle to achieve the desired bottle pressure (above 900 psi) and retard the ignition timing before engaging our power adder. Applied properly, the ZEX system can safely add as much as 300 extra horsepower, or twice as much as we applied to this 350.

If you haven’t already check out Power Adders Part 1 where we added boost to this same small block.

Sources

COMP Cams
compcams.com

Edelbrock
edelbrock.com

Holley/Hooker
holley.com

Lucas Oil
lucasoil.com

MSD
msdignition.com

ZEX
zex.com