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Jeep Cherokee I-6 Zex Wet Nitrous System

Posted in How To on December 1, 2009
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Photographers: Jerrod Jones

Nitrous oxide (NO2) can be a finicky power adder for your engine. It is composed of two oxygen molecules for every one nitrogen molecule. This mixture is not a fuel and doesn't produce power by itself, but it gives you the ability to burn more fuel to create more power-think of it as a catalyst. If used improperly, it has the potential to blow engine parts through your truck's hood. However, when used correctly with the sufficient components, nitrous oxide will without a doubt provide the most amount of power for the least amount of money. It can be used on nearly any engine without severely degrading the life of the engine. Generally, nitrous is considered a mod that only gets plumbed into little tuner cars or large V-8s that displace lots of cubic inches and have a quarter mile to go. But with so many guys trading in their V-8s for four and-six-cylinder ORVs, it was time to see what a bottle of NO2 could do to a mild Jeep I-6. We didn't want a kit that would break our bank, nor did we want one without any safety parameters that would stop the nitrous flow if the fuel flow stops. It sounded like a stretch, but after talking to Zex we were confident it could be accomplished with its 4 &-6-Cylinder Nitrous System for EFI engines.

There are various delivery methods to get the nitrous in the engine, but they are mainly distinguished as either a "dry" or "wet" kit. In an EFI-equipped engine, a dry system injects only nitrous into the intake. It then relies upon tricking the factory ECU into dumping more fuel into the engine to mix with added nitrous oxide. Dry systems can only add small amounts of horsepower (around 60 hp) because they utilize stock injectors to dump more fuel. A wet system actually plumbs into your existing fuel lines and not only dumps nitrous oxide into the engine, but also extra fuel (usually combining the two at a single nozzle) just upstream of the throttle body. Much more power can be safely added to an engine with a wet system, but a good rule of thumb is to never add a nitrous shot that produces more than 33 percent of the engine's [pre-nitrous] power. With 100,000 miles on our stock inline 6's fuel injectors and engine sensors, we decided to go with a Zex wet system that would provide a 55 to 75 hp shot of nitrous. We also obtained the Blackout edition of the kit that uses black fuel and nitrous lines, a black control box, and a black nitrous bottle. We figured it made sense to keep the nitrous kit as hidden as possible.

The ZEX wet system uses a Nitrous Management Unit which controls the entire nitrous system, has built-in safety systems, and makes for a simple two-hour installation. This pre-assembled unit uses features such as Zex's patented Active Fuel Control to monitor the bottle pressure and regulate the amount of fuel added to the mixture. This ensures that the engine is never run too rich or too lean. The Zex kit also utilizes a simple and intelligent activation method: the Nitrous Management Unit (NMU) learns the voltage curve of the vehicle's throttle position sensor (TPS) and when powered, will activate injection at wide open throttle (WOT). The fuel and NO2 is the fed to the Zex nitrous nozzle where it is mixed and then finely atomized during injection by the nozzle's patent pending Fuel Shear technology. This kit is adjustable between a 55 hp and 75 hp shot of nitrous with the use brass nozzles of varying diameter to limit the amount of nitrous available.

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Memphis, TN 38118

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