Ford 306 ZEX Test

Words and Photos: Richard Holdener

How many times have you been behind the wheel and found yourself wanting just a little more power? Heck, let’s not stop at a little more. How many times have you wanted a LOT more? What if there was a way to have an extra 100 HP at the push of a button? Wouldn’t that come in handy when it comes time to pass some unsuspecting Camaro? Well my friends, on the other end of that push-to-pass button is a little something we call boost in a bottle. By boost in a bottle, of course, we are referring to the amazing substance known as nitrous oxide.

For those unfamiliar with nitrous oxide, there are at least three important things you should know. In no particular order, the three things (there are actually more) include nitrous being effective, easy to use, and inexpensive. Actually, we will add a fourth here, as every car guy or gal should try nitrous oxide at least once in their life. There is nothing quite like unleashing the surge of an extra 100-plus HP (and even more torque) at the simple push of a button.

Before getting to the test on our 306 Ford small block, it might help to better understand just what nitrous oxide is — and isn’t. We know already that nitrous oxide adds power, so right away, it must be explosive, right? WRONG! Despite what we constantly see on the big (and small) screen, not only is the compound not explosive, it is not even flammable. That’s right, all of those explosions are created not by the volatile mixture, but by the special effects team (can you say C4). Heck, nitrous oxide isn’t technically a fuel, like gasoline, but rather an oxidizing agent. The mixture is certainly capable of improving the power output of your average internal combustion engine, but it must first be combined with the necessary fuel. What this means is that your engine will not run on nitrous oxide alone, and that even if you exposed a match to the stream, it would simply be extinguished. Since the boiling point (when it turns from a liquid to a gas) is at a chilly -129 degrees, you are much more likely to freeze you hand or finger trying to touch the stream (don’t try).

If it doesn’t explode, then how, you might ask, does it add power? The power augmentation offered by nitrous oxide works only after the oxygen molecules are liberated from the compound. Breaking down the compound requires considerable heat, with temperatures approaching 572 degrees. Lucky for enthusiasts, this temperature is easily achieved during the combustion process. Unlike the compound, the free oxygen molecules are flammable and free to enhance burning of the additional fuel. The combination of extra oxygen and additional fuel produces power.

Making things even better is the fact that when the nitrous is injected, it is transformed from a liquid to a gas. The gas is supplied to the engine at -129 degrees, further cooling the inlet air. As we know, cooler air offers more oxygen-producing molecules, thus we have additional power production offered by the compound. A side benefit of the drop in temperature is that it can also reduce the possibility of harmful detonation.

Now that we have a better understanding of nitrous oxide, let’s take a look at the system applied to our 306 Ford. According to tech pros over at ZEX, their fancy Perimeter Plate configuration offers not one, but a trio of beneficial design features. These features included Perimeter Injection, Cryo-Sync, and Airflow Enhancement Technology.

It should come as no surprise that any V8 (like our 306) is made up of eight individual cylinders. Given the power potential of nitrous oxide, it is critical to achieve proper distribution to those eight individual cylinders. Unlike other systems, the Perimeter Injection is designed to enhance cylinder-to-cylinder distribution. Though sandwiched between the carburetor and intake manifold like other plate systems, the Perimeter Plate employs 12 equally spaced injection points. These combine the required nitrous and fuel to both optimize atomization and equalize distribution. The distribution of a substance at -129 degrees through the plate also makes it an ideal heat isolator (or Cryo-Sync). The final benefit is the increase in airflow through the carburetor caused by the injection of high-pressure nitrous from the plate.

While these benefits sound all well and good, we still wanted to put them to the test on our little Ford. The BPE 306 test motor was now well used, having been run numerous times. Originally supplied as a short block, the 306 featured a healthy hydraulic roller cam (.543/.554, 218/226, and 112 lsa), a set of BPE as-cast, aluminum heads, and a Speedmaster dual-plane, Eliminator intake. To this, we added a set of 1.6-ratio COMP Cams Ultra-Gold ARC roller rockers, a 650 carb, and 1 ¾-inch, long-tube headers. We even dusted off an old set of composite valve covers (in Ford blue) from COMP Cams.

Run on the dyno in normally aspirated trim, the carbureted 306 produced 368 HP and 359 lb-ft of torque. After installation of the ZEX nitrous kit (with 100-HP jetting), the power numbers jumped to 482 and 461 lb-ft of torque. The best part about the power gain was that it came at just a push of the button. Furthermore, the kit had jetting to support as much as 300 HP, so there was plenty left should the need arise. Trust us; you owe it to yourself to try push-to-pass power at least once!

Graph: BPE 306 Ford-NA vs Zex Nitrous (100-HP)

Nothing is easier to install or easier on the wallet than a simple nitrous kit. There is nothing like adding an extra 100 HP to your Ford small block at the simple push of a button. Run in normally aspirated trim, the 306 Ford produced 368 HP at 6,100 RPM and 359 lb-ft of torque at 4,100 RPM. After activation of the ZEX nitrous kit, the Perimeter Plate system increased the power output to 482 HP and 461 lb-ft of torque. Since the kit has jetting to support 300 HP, there was plenty more power to be had on this 5.0L.