Richard Holdener
October 1, 2008

What's the first thing that comes to mind when we tell you it's possible to add an easy 100 hp to your modified 5.0 motor (or other Ford) with one simple bolt-on? Because of the impressive power gain, you'd be right on target thinking the single bolt-on was some type of forced induction, given the boost craze lately. But in this case, you'd be wrong.

If boost isn't the bolt-on of choice, then the extra 100 hp must come from the old standby nitrous oxide, right? Actually, you're only half right, as the installation of a simple plate nitrous kit like the one we tested from NOS will easily add the requisite 100 hp, but so too will the right set of cylinder heads. What's that you say, 100 hp from a simple head swap?

Which one is worth 125 extra horsepower-nitrous or the right set of cylinder heads?

How on earth can a set of cylinder heads offer as much extra power as a nitrous system? While it's true that you'd be hard pressed to get these kind of gains from just any set of performance heads on any 5.0 motor, installing the heads on the right combination can yield impressive dividends that rival the power offered by the ol' bottle.

To understand the comparison test, we should take a closer look at how the two bolt-ons go about adding power, starting with the bottle. One of the most common misconceptions about nitrous oxide, one fueled by Hollywood's entertaining but misguided attempt at covering the undercover world of street racing, is that it's a fuel. While nitrous oxide will indeed enhance the power output of your Ford, no 5.0, 4.6 or 5.8 Windsor could run on nitrous oxide alone. The reason is that (again, unlike in the movies) nitrous oxide does not burn. While this statement may seem contradictory to its unique ability to greatly increase the power output of an internal combustion engine, there's much more to the equation than simple flammability. As we will discover, nitrous oxide has a number of unique characteristics that make it ideal for power enhancement.

The test motor came from the good folks at Coast High Performance. The 331 started out as a late-model 5.0 block. The CHP stroker kit included a cast 3.25-inch stroker crank and forged connecting rods.

Though certainly not a fuel, nitrous oxide does greatly enhance the combustion process. Technically speaking, nitrous oxide is an oxidizing agent. The additional power produced by the injection of nitrous oxide comes from the release of free oxygen molecules. The two ingredients in the basic recipe for power are air and fuel, of course assuming the two are combined in the correct ratio. In this formula, air is a rather generic term. The air we breathe is made of a number of chemicals, the two most common of which are oxygen and nitrogen (incidentally, just like the composition of nitrous oxide). It's actually the oxygen present in our generic "air" that burns to produce the expansion necessary to push pistons and rotate our crankshafts. Performance enhancements, such as turbocharging, supercharging, and most forms of normally aspirated modifications (ported heads, cams, and intake manifolds) all seek to supply the motor with additional airflow. The additional airflow increases the amount of oxygen available to burn, thus increasing the "potential" power output.

Unlike these other forms of power enhancement, nitrous oxide supplies the additional oxygen molecules in chemical form. In addition to other important benefits, this chemical supercharging eliminates the heat generated by a typical turbo system and the power losses associated with driving a mechanical supercharger.