Words and Photos: Richard Holdener
When you go looking to improve the power output of any motor, there are a lot of different performance choices. Some gravitate to increased displacement, as there is no replacement for displacement, especially if you are looking to greatly enhance torque production. Nothing bolsters torque like a stroker kit, but that isn’t the only avenue for performance enthusiasts. Obviously, basic bolt-ons are every bit as popular as displacement, probably more so. The bonanza of bolt-ons include everything from simple carburetors (or throttle bodies) and intakes to cylinder heads and camshafts. There is an impressive amount of power to be had from the right combination of cylinder heads, camshaft and intake manifold. Of course, there is always boost, as either a turbo or supercharger will easily improve the power output of any motor. The final power producer, and the one we chose to add first to our 5.0L, was nitrous oxide.
For those not familiar with the wonders of nitrous oxide, the two important things you should know are, what it is and what it isn’t. First off, it is amazing, as it is possible to add 100, 200 or even 300 hp (or more) to any engine combination at the simple push of a button. While nitrous oxide IS amazing, it isn’t flammable. Contrary to all the exposure, it doesn’t blow up in the spectacular fireballs depicted on the silver screen. The reason for the lack of fireworks is that nitrous oxide is simply an oxidizing agent. It has the potential to greatly increase the power output of your motor, but only when mixed properly with sufficient fuel.
Were you to touch a match (or even a full-blown torch) to an open stream of nitrous oxide, there will be no explosion. In fact, the ice cold (-129 degree!) gas will more likely extinguish the fire. For this reason, and the fact that nitrous oxide is store as a liquid at very high pressures, care must be taken when working with it, but only the Hollywood special effects team can make a car blow up!
If it’s not a fuel, and doesn’t blow up, how exactly does nitrous oxide increase the power output of your motor? The key to the success of the compound is, that it is indeed a compound, and made up of nitrogen and oxygen, not unlike the air we breathe. For power production, we are most interested in the all-important oxygen molecules in the compound, unfortunately, the nitrogen and oxygen are understandably reluctant to part ways.
Releasing the oxygen molecules requires an input of heat, in this case approximately 572 degrees worth. As luck would have it, there is more than enough heat in the combustion process to liberate the oxygen molecules. The free-roaming molecules can then be combined with extra fuel (gasoline) and ignited to greatly enhance the power output. The nitrous oxide basically adds oxygen molecules, not unlike supercharging, but does so in chemical form. As a side benefit, the nitrous oxide is stored under pressure as a liquid, then released as a gas (a process call vaporization) at a chilly -129 degrees, thus super cooling the inlet air.
For our rebuilt 5.0L, we chose a ZEX Perimeter Plate nitrous system. The Perimeter Plate nitrous system featured 12 equally spaced injection points to properly distribute the supplied nitrous and fuel. Jetting supplied with the kit allowed us to adjust the power increase from 100 hp-300 hp, but we had a jet kit that allowed us to drop down to just 75 hp. We wanted to start small with our mild motor, but rest assured it will take more nitrous. We’ve run 125-hp shots successfully on a stock 5.0L for years, much to the dismay of a great many Chevy owners. The test motor was equipped with a dual-plane intake from Speedmaster, along with a four-barrel carb, billet distributor and set of headers before installation of the nitrous kit. Run in this configuration, the 5.0L Ford produced 258 hp at 4,600 rpm and 328 lb-ft of torque at 3,600 rpm. Before adding the ZEX nitrous to the mix, we retarded the ignition timing by 3 degrees. Using the 75-hp jetting on the ZEX kit, the nitrous-injected 302 produced peak (spike) power numbers of 354 hp and 416 lb-ft of torque, but the kit offered consistent power gains of 75-80 after the initial activation spike. What could be easier?
Graph 1: 302 Ford-NA vs ZEX Nitrous (75-HP)
The rebuilt 5.0L long block was stone stock, including the camshaft, cylinder heads and cast internals in the short block. While some may question the use of nitrous oxide on a motor with a cast crank, rods and (most importantly) pistons, trust us, it’s all good! We have run nitrous on numerous stock motors, including 5.0L Fords, with great success. With the 302 sporting a four-barrel carb, dual-plane intake from Speedmaster and a set of headers, it produced 258 hp at 4,700 rpm and 328 lb-ft of torque at 3,600 rpm. After installation of the ZEX Perimeter Plate nitrous system, the power output jumped as high as 354 hp and 416 lb-ft, but the 75-hp shot actually improved the power output by 75-80 hp through most of the curve (the 354 hp was a spike).