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Diesel Nitrous System - Diesel Tech

How A Nitrous System Can Turn Your Power Stroke Into A Lightning Beater

Luke Magnus
Feb 21, 2007
Photographers: Luke Magnus
The power of nitrous-oxide injection. Great for race cars, right? But for diesel pickups? Come on!
Photo 2/19   |   Our '99 F-250 Ford Super Duty pickup sports a 7.3L Power Stroke diesel engine with 167,000 miles of hard hauling use, but in terms of diesel life, it's just getting started. This truck is completely stock with no modifications.
It may not be mainstream yet, but nitrous oxide is a great way to provide a performance boost for your street-driven or racing diesel truck. Tired of turbo lag and looking for a quick kick in the pants on demand? Nitrous-oxide injection can get you there. The ZEX diesel nitrous system is a complete kit that includes everything needed to safely and easily add 35-200 additional horsepower. The kit includes a 10-pound bottle, bottle brackets, nitrous solenoid, and all required hoses and wiring. Best of all, it takes about two hours to install and won't hurt your engine. Yep, even you can't do it wrong.
The test vehicle for our ZEX nitrous system installation was a '99 Ford F-250 equipped with a Power Stoke 7.3L engine. Stock in every meaning of the term, this truck had no modifications, but it also had one key ingredient: a willing owner who trusted us to make his truck faster.
There are plenty of myths surrounding nitrous oxide injection-lots of scary stories about what it can do to the insides of your engine. The plain truth is that nitrous oxide is simply a combustion enhancer, bearing no relationship to "nitro," that volatile fuel used in extreme drag racing environments. When nitrous oxide is added to the combustion process with the correct amount of fuel, it dramatically increases the horsepower output. Diesel engines are the perfect platform for nitrous injection. Since most diesel engines run a rich fuel mixture (denoted by the signature black smoke they can emit from the tailpipe), nitrous oxide helps burn this excess diesel fuel in the combustion chamber, extracting additional horsepower. As opposed to other horsepower enhancers like propane, nitrous oxide actually cools the exhaust-gas temperatures generated by the engine, which is the critical factor limiting the power output of diesels.
The ZEX diesel nitrous system is termed a "dry system," meaning no additional fuel is injected into the engine by the kit, as is the case with most gasoline-burning nitrous systems. The reason is simple: a fuel-rich condition generally exists in most diesel engines after a performance programmer tune has been added. It is this extra fuel that we are looking to burn with the ZEX diesel nitrous kit. During our testing on the chassis dyno, we initially sprayed the nitrous with the engine's computer totally stock (OE form). The engine with stock programming saw no power gain with the nitrous. The stock tuning is "clean" and has little, if any, fuel left over for the nitrous to burn.
To increase the power output at this point, more fuel was introduced into the engine electronically through the vehicle's own fuel-delivery system with a SCT Fast-Flash Power Programmer. Hooked into the diagnostic port under the dash, the Fast-Flash walks the operator through a simple process that reprograms the engine's computer to increase fuel delivery. In tandem, we also increased the nitrous-system jet sizes while watching our power levels. It's a simple cause-and-effect relationship: add more fuel and nitrous to make more power. The beauty of the diesel system is your engine makes more power with cooler exhaust temps. Once the existing fuel is burned-regardless of the nitrous injected-you're done, and the excess nitrous exits out the tailpipe. But be forewarned, if you add too much nitrous, your engine will start to lose power. For those folks looking to install the 200hp jet right off the bat without increasing the fuel through the Fast-Flash, we've got news for you. Don't do it. The engine will actually run worse because the excess nitrous will start to extinguish the fire in the combustion chamber. Go slow, and take the steps required to find the right balance of fuel, nitrous, and horsepower.
The ZEX diesel nitrous system features special electronics that perfect the nitrous system engagement. The ZEX diesel nitrous kit's activation switch simply wires into your throttle position sensor (TPS), programs itself to your truck and, once armed, activates at wide-open throttle. This way, you avoid triggering nitrous injection during part-throttle conditions where less-than-peak power can be generated.
So follow along with the steps outlined in this article, and then go find a Ford Lightning to race. Have your camera ready to snap a few photos of stunned facial expressions. Diesel power all the way!
The chart tells the story. Note that our increase in performance
was close to {{{100}}} hp greater than the bone-stock
output—a huge improvement.
BASELINE 183 hp at 3,250 rpm
FAST-FLASH TUNE 215 hp at 3,350 rpm
55hp JET 230 hp at 3,350 rpm
75hp JET 242 hp at 3,400 rpm
100hp JET 354 hp at 3,350 rpm
150hp JET 278 hp at 3,400 rpm