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Adding 171 Dyno Proven Horsepower With Zex Nitrous

By Richard Holdener

If Street Outlaws and the Fast and the Furious franchise are any indication, nitrous oxide is as popular as ever — and for good reason. Nitrous oxide has a lot going for it, including significant power gains, low cost, and ease of installation. Let’s not forget how easy it is to conceal, for those looking for the ultimate in performance deception.

Initially used as both an anesthetic and as a performance enhancement for British and German World War II aircraft, it eventually trickled down to hot rodders and racers looking for the ultimate bang for the buck. If someone ever writes the quintessential book, titled Cheating to Win, rest assured it should contain at least a full chapter on nitrous oxide.


It is amazing what a difference this simple, little purple plate makes to the performance of your Ford. The Zex Permimeter Plate nitrous system really woke up our 347-stroker small-block.

Nitrous oxide has been present (if not always visible) at the top levels of drag racing, NASCAR and even the Brickyard. That’s right folks; more than one, down-on-power team at the Indy 500 relied on a little boost in a bottle to qualify for the show.

Though chock full of serious potential, nitrous oxide is chemically similar to the air we breathe. It only lacks the more stable oxygen molecule (N2O versus N2O2). The key to power potential of nitrous oxide is actually the oxygen contained in that compound.


Based on a late-model 5.0-liter block, our 347 featured a forged rotating assembly, including a 3.40-inch stroker crank and a set of 5.40-inch connecting rods from Speedmaster. These were combined with a set of JE forged pistons and Total Seal Rings. We also added a Comp XFI cam and CNC-ported, ProMaxx aluminum heads.

One common misconception about nitrous oxide, perpetuated by both TV and the movies, is that it is both flammable and explosive in nature. The truth is that touching a match (or even torch) to the chilly stream of nitrous oxide will result in said fire being simply, and easily, extinguished. Despite the depictions, there will be no huge explosions and no fireballs – not even so much as a flickering flame. The special effects teams get all the credit for exploding cars, albeit improper heating or damage to the pressurized bottle can certainly create havoc. 



Nitrous Science

Chemically speaking, the oxygen in the compound is certainly flammable, but the compound itself is not. It is only when the oxygen molecules are liberated from the compound that they can be used in conjunction with fuel to produce extra power. To release the oxygen molecules from the compound, the nitrous oxide must first be heated to 572 degrees (in the combustion chamber).

  


The ported heads and healthy Comp XFI cam were fed by a single-plane Edelbrock Victor Jr. intake. Controlling the air and fuel to our test motor was a Holley 650 Ultra XP carburetor. To ensure the nitrous combo had plenty of spark energy, we installed this MSD billet

distributor and a 6AL ignition amplifier. Run on the dyno with Hooker headers, a Meziere electric water pump and Speedmaster neutral damper, the 347 produced 441 horsepower at 6,500 rpm and 405 lb-ft of torque at 5,000 rpm. 

"As if the extra power wasn’t enough, the compound also offers a side benefit in the form of charge cooling."

Technically, nitrous oxide is not a fuel, but rather an oxidizing agent. Once released, the free oxygen molecules work to support (or enhance) the combustion process. This process requires burning some other fuel, like gasoline or methanol. As if the extra power wasn’t enough, the compound also offers a side benefit in the form of charge cooling.

Nitrous is stored as a liquid, and when injected, it is converted into a gas. This process is called boiling, though it occurs with nitrous oxide at a chilly -129 degrees. The conversion from a liquid to a gas absorbs a great deal of heat from the surrounding area, to say nothing of the added benefit of the introduction of a compound at -129 degrees to your inlet tract.

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