Turn Your Mild-Mannered Two-Valve Into A Test-And-Tune Terror.
As This is MM&FF's all-nitrous/all-the-time issue, we didn't want to leave out the 4.6L Two-Valve crowd, so here we are satisfying the SOHC Mustang's need for speed.
This story actually turned out to be as much an article about polishing your driving skills as it is going fast with the juice. Our test driver for the article visited the track occasionally, but a bit of coaching had him slashing the e.t. slip and showing what the nitrous system could really do by the end of the night.
The nitrous kit of choice is a Zex wet system (PN 82217) that delivers a cool shot of nitrous oxide along with an extra helping of pump gas, to boost your engine's output anywhere from 50 to 175 hp. The system fits '99-'04 Mustang GTs and includes Zex's patented Active Fuel Control. This feature automatically adjusts the nitrous fuel enrich-ment so your engine never runs too rich or too lean. The system also features a patented electronic TPS switch for perfect activation at wide-open throttle. For the install, we also employed Zex's new window switch to make sure the nitrous flows between a given set of rpm limits. With the Zex control unit tapping into the throttle position sensor to know when we're on the hammer, and the window switch guiding delivery, the added horsepower is virtually maintenance-free. Just flip the switches, make sure the bottle pressure is high enough, and let it rip.
In addition to the nitrous system (PN 82217), we also ordered the Racer's Tuner Kit (PN 82001), which includes a bottle-pressure gauge, bottle heater, blow-down tube, and purge kit. We also chose Zex's traction-control window switch (PN 82085).
After a professional installation at the very capable hands of the HP Performance staff in Orange, Park, Florida, we hit a local test and tune night to find out how fast the nitrous would make us go, and what kind of competi-tion we could mow down with it. Our subject vehicle, belonging to Gregg Brewer of Jacksonville, Florida, is an '04 40th anniver-sary GT that's more at home on the show circuit than on the strip. However, Brewer had taken it to the strip to flog it in naturally aspirated form, so we had a baseline to verify improvement.
Truth be told, Brewer's driving needed to be honed a bit, coaxing a 13.99 out of the mildly modified Two-Valve 4.6L mill with help from a set of Mickey Thompson Drag radials. On this night, we opted for a set of M/T ET Street tires to get some bite. This would be Brewer's first time on a bias-ply/radial-tire combination, so we mentioned to him that there may be some sway at the top end.
At the track, the Zex 100hp of nitrous slashed elapsed time by more than a second, with our best run of the night coming in at 12.65 at 108 mph.
Unfettered by our advice, Brewer brought the Dark Shadow Gray colt into the burnout box. Although getting drag radials to smoke isn't too much of a chore, the ET Streets we were using were a bit old and dry and needed a good smoke session to get them gooey, but our man Gregg didn't stay in the burnout long enough. On his first pass, he came out of the hole at about 3,000 rpm. When the nitrous hit, the tires spun, and when he dialed up Third gear, no one was home. Still, we managed a 13.50 at 105 mph. Chalk this one up to nerves. The instant surge of the nitrous hit is fun when it's harnessed, but coupled with tire spin, it can be a handful.
It's important to note that we were distracted enough by the action at the track to let Brewer hot lap the car after every run. The engine was definitely at full operating temperature, and the bottle heater barely had time to maintain the 975 psi of pressure. That being said, our SOHC Stang was up for Round 2 about 10 minutes after the first run. Brewer explained the Third-gear problem, and we told him that he needed a better burnout, which he did improve on, but not enough as more tire spin ensued. Still, the Stallion ran a much improved 13.10 at 106 mph. His next attempt featured a similar burnout, yet the elapsed time dropped to a 13.05 at 107 mph.
First and foremost, do not use Teflon tape in any nitrous installation. No matter how careful you are, there's always the possibility you might get some of it in the nitrous system, and that can be very, very bad. With that public service announcement out of the way, we began our install by disconnecting the negative battery terminal and loosening the bolts on the fuel-pressure sensor on the driver-side fuel rail. As the bolts are unscrewed, fuel will spill out, so have a rag underneath to catch the extra fuel. | 
Lube the O-rings on the fuel rail adapter and place it on the fuel rail where the sensor was. The sensor will then snap on top of the adapter. With the adapter and sensor mounted using the supplied hardware, connect the fuel line to the adapter. The other end connects to the nitrous-management unit, which we'll take care of later. | 
Next up is mounting the Zex nozzle. At this point, you'll need to figure out where the nitrous-management unit will reside. The braided lines are only so long, so take that into consideration and place them accordingly. Zex recommends mounting the nozzle 6-18 inches from the throttle body, and we ended up about 6. We drilled a 9/16-inch hole in the intake tube and screwed in the bulkhead fitting, followed by the nozzle. |