We wanted quick, easy power....
We wanted quick, easy power. Follow along as we install a Zex nitrous-oxide kit on a Magnum and lower our elapsed times.
When it comes to horsepower, we prefer it cheap and easy, and when it comes to cheap and easy horsepower, there's really no substitute for a dose of nitrous oxide. Although nitrous oxide has a bad reputation as an engine killer, the reputation is largely unfounded and likely started back before the advancement of nitrous technology. Today nitrous oxide, when used properly, is a safe and efficient power adder and is likely the cheapest source of horsepower available for your car. So when the folks at Zex told us they'd developed a nitrous system for the new LX platform cars with a Hemi, we had to try it out.
To safely use nitrous oxide as a power adder, we first need to understand the principles of nitrous oxide. Nitrous oxide itself adds no power to an engine; in fact, nitrous oxide isn't even combustible. Adding nitrous oxide to an engine without supplying the proportionate amount of gasoline (or diesel fuel in diesel applications) will only cause an extremely lean condition, which leads to detonation, heat, and, eventually, engine damage. The chemical compound of nitrous oxide is not a fuel, but an oxidizer, which is utilized to get more oxygen into the cylinders of an engine. Getting more oxygen in an engine allows more fuel to be introduced, thus allowing a more combustible mixture from which power can be derived. So the power doesn't come from the nitrous itself, but from the fuel that is added to combust with the oxygen in the nitrous oxide.
The folks at Zex have taken nitrous-oxide injection to new levels, providing safe, efficient nitrous-oxide kits for both racing and street applications. Their kits for the new Hemi applications meter the fuel and nitrous oxide accurately, preventing detonation and the costly damage it can cause. Additionally, the Zex kits monitor the car's electronic throttle position sensor, so the nitrous oxide and fuel are only added at full throttle. Rather than utilizing a push-button switch to activate nitrous system solenoids, the Zex system incorporates the solenoids and switches into one unit, making the system easy to use and easy to install with fewer parts than comparable systems. There's simply one switch to arm the system, then as soon as the Zex control unit recognizes acceptable engine parameters and application of full throttle, the nitrous oxide and fuel are injected into the engine's air-induction system.
When we say the Zex kit is complete, we mean they thought of everything. All the plumbing, wiring, and necessary components are included in the system, and the instructions are clear and concise. They even thought to include a pipe-thread tap to cut threads for the injector in case we needed it. As it turns out, our induction tube didn't need to be tapped, but it's nice to know they included the tool just in case. The system is tunable in three steps--75, 100, and 125 hp--simply by changing the fuel and nitrous jets in the injector. All the jets are also included with the system. All told, our installation took about half a day and only required basic hand tools.
With our system installed, we were eager to head to Bradenton Motorsports Park for some testing. Of course, we had to see if everything was functioning correctly on the way to the track, and we were impressed by the additional power provided even with just the 75hp jets installed. Once at the dragstrip, we were pleasantly surprised. After our non-nitrous, baseline pass netted a 14.32 in the quarter, we turned on the nitrous for another lap. Though we hadn't really allowed the car to cool down, we still blasted through the quarter at 13.97, gaining 4 mph through the traps as well. After a short cool-down period, our second nitrous pass netted a 13.92 and gained 1 more mph. Unfortunately, a rain shower ended our test session before we could step the nitrous up to its higher power levels, but we're confident elapsed times would have dropped by at least another two-tenths.
All told, we were impressed by the Zex system. It's easy to install, and one of the cheapest ways you can add up to 125 hp to your new 5.7-liter Hemi. Be sure to look for further testing of this system in future issues as we'll step up the power to achieve even better elapsed times.
The Zex engineers thought...
The Zex engineers thought of everything, including all the components, plumbing, and wiring necessary to complete the installation.
The engine bay of a Hemi-equipped...
The engine bay of a Hemi-equipped Magnum is already pretty full, but we found ample room for the Zex components.
We began our project by mocking...
We began our project by mocking up components to see where they'd fit. After trying several locations, we decided to mount our nitrous-oxide/fuel-control unit on the driver-side inner fender.
For proper nitrous oxide and...
For proper nitrous oxide and fuel distribution, the system nozzle should be placed 6 to 18 inches from the throttle body blade. After determining the best position for our nozzle, we marked our intake tube and removed it to drill the provision for the nozzle.
With the air inlet tube removed,...
With the air inlet tube removed, we drilled the pilot hole for the nozzle, then enlarged it to 9/16-inch and installed the nozzle assembly.
We made sure the nozzle was...
We made sure the nozzle was installed to direct the nitrous oxide and fuel mixture with the flow of air in the inlet tube.
Since we really don't like...
Since we really don't like drilling holes in someone else's new car, we decided to mount our control unit with an existing fastener on the inner fender. We also grounded the unit to the same fastener.
To supply fuel to the nitrous...
To supply fuel to the nitrous control unit, Zex supplies a new fuel feed line with a provision for an additional fitting.
The new fuel line simply clips...
The new fuel line simply clips into place where the original fuel supply line went. Now the fuel line can be routed from the new line to the control unit.
Bottle position is important...
Bottle position is important in any nitrous system. We installed ours in the Magnum's rear cargo area with the mounts included with the kit. The valve should be higher than the bottom of the bottle, and having the valve face the front of the car is optimum.
We routed our nitrous supply...
We routed our nitrous supply line from the engine bay, under the car, then through one of the plastic plugs in the rear floor just ahead of the rear seat and back to the cargo compartment where our bottle is.
With our lines routed and...
With our lines routed and our components in place, we installed all the remaining high-pressure lines.
Wiring the system was easy....
Wiring the system was easy. we simply grounded the black wire, ran the red wire through the firewall to a 12-volt supply and arming switch, then the remaining white wire was tied to the Throttle Position Sensor output voltage wire.
After wiring the system, the...
After wiring the system, the throttle must be opened without the engine running so the Zex control unit can "learn" the voltage of the TPS switch. Since the new Hemis are throttle by wire, the gas pedal only opens the actual throttle blades with the engine running, so you'll have to manually open the blades with the air inlet off to complete this procedure.
Nitrous oxide and fuel are...
Nitrous oxide and fuel are metered by these jets in the nozzle. Zex includes jets for 75, 100, and 125hp tuning. We started with the 75hp jets so in case we have a problem with the system, we'll be less likely to do any major engine damage.
Since our Magnum has a Hyperpack...
Since our Magnum has a Hyperpack performance tuner, we had to re-set the car's computer to stock settings. Computer tuners typically vary ignition timing, which can lead to detonation when nitrous oxide is used. Setting the computer back to stock settings ensures the ignition timing is suitable for nitrous oxide use.
Though a rain shower would...
Though a rain shower would end our test session before we could step the nitrous up above its 75hp level, we managed several 13.90 passes in the Florida heat. Not bad for half a days work and a flip of the switch! Look for more thorough testing in future issues and on our web site, moparmuslcemagazine.com.
After making a baseline pass...
After making a baseline pass with no nitrous, our first nitrous pass netted a 13.97 in the quarter-mile, more than four-tenths of a second quicker than without nitrous!