Nitrous vs Cylinder Heads - Bolt-Ons Vs.The Bottle

As the name suggests, the compound nitrous oxide, or dinitrogen monoxide, is composed of two nitrogen molecules and a single oxygen molecule. When heated to approximately 572 degrees F, the compound is broken into its component parts, thus releasing free oxygen molecules in the process. It's the release of these oxygen molecules that support (or more accurately, enhance) the burning of the flammable fuel (gasoline) already present in the system. As a side benefit, the released nitrogen acts as a buffer or antidetonate to allow dramatic increases in power while maintaining a given detonation threshold. In short, it's possible to add 100-150 hp to even a stock motor without fear of detonation. Of course, this assumes the correct ignition timing and air/fuel ratios are part of the equation. Pure oxygen, while offering plenty of power-producing oxygen molecules, does not possess the necessary detonation suppression quality to allow for use in performance applications. Uncontrolled burning, elevated heat levels, and a dramatic change in the detonation threshold all but eliminate the use of pure oxygen as a form of chemical supercharging.

We mentioned earlier that the power gains offered by nitrous oxide come from the release of the free oxygen molecule. Though accurate, nitrous oxide enhances the power output of an internal combustion engine in other ways as well. Nitrous oxide used for automotive applications is stored in a pressurized container (bottle) and supplied to the motor in liquid form. Once delivered to the inlet tract, the liquid turns into a gas, a process called vaporization. This transformation from a liquid to a gas requires an input of energy; in this case, the energy is heat. The vaporization of the liquid nitrous absorbs heat from the inlet air, a desirable characteristic on any motor, especially one equipped with forced induction. Once vaporized, the temperature of the nitrous oxide is still at or near -129 degrees (the boiling point of nitrous oxide). Naturally with such a low boiling point, the -129-degree nitrous still provides a dramatic cooling effect on the inlet air. This double cooling not only reduces the chance of detonation, but also increases the density of the inlet air. The denser air provides more oxygen molecules, which in turn creates more power. With so much going for it, it's easy to understand why so many street racers employ the use of nitrous.

It should be obvious from the discussion on nitrous oxide that the power output of a motor is dependent on the number of oxygen molecules it can ingest. Increasing the power output of a motor is as simple as increasing the airflow (or oxygen molecules) into the motor. Unlike nitrous oxide, cylinder heads don't possess free oxygen molecules, and therefore must provide the oxygen in the form of additional airflow. Where the nitrous oxide is forced into the induction system, the power gains offered by a set of performance cylinder heads is dependant on other factors. What this means is that adding a set of fully ported race heads to your otherwise stock motor will not offer much, or any, additional power, despite the fact that the race heads offer twice the airflow of the stockers. More airflow from the heads (as tested on a flow bench) does not necessarily equate to more power. For the additional airflow to be converted into power, the airflow must be increased through the motor-more airflow in equals more power out.