Nitrous Oxide Injection - Go With The Flow

Nitrous Madness!
The exact time and place of the first use of nitrous in an automotive application is not known, but we do know that it occurred in the mid-to-late '70s. The instant rush of power sent diehard hot rodders into disbelief and immediately labeled the wonder drug as a sort of "cheating" way to get horsepower. It was perceived as being too easy, and enthusiasts who used nitrous were considered not as good as people who went the all-natural route.

Fast-forward 30 years later and most will agree that nitrous is not only acceptable, but one of the most popular modifications Mustang enthusiasts can make. Ford's latest Pony powerplant is no different--and the sauce (as it is commonly referred to) is a popular addition to both naturally aspirated and forced-induction combinations.

Nitrous oxide injection is as effective on this engine as it is on any other motor out there. The complex electronics did force manufacturers to rethink the arming system but once it was overcome, it was business as usual. Adding nitrous to the S197's Three-Valve motor is as easy and cheap as any other EFI system. Over the years, MM&FF has tested many different nitrous kits for the '05-'07 Mustangs, including over-the-top 600-plus horsepower force-fed combos. This time, we enlisted the help of Real Speed Automotive (Bohemia, New York) to add a Nitrous Pro Flow wet system to a near stock '08 Mustang GT. Real Speed keeps Nitrous Pro Flow kits in stock, so anyone can show up and be juiced right away.

Adding a nitrous kit to the '08 Stang is a bit different than its predecessors, as there are two changes under the hood when compared to the '05-'07 models. First, the Nitrous Pro Flow solenoids are bolted to a bracket coming off the strut tower. The '08 models do not have that same bracket; the NMRA Real Speed crew used self-tapping screws to mount the solenoids in the same location. We felt that mounting it there would mean we wouldn't run into any problems with the pre-made fuel and nitrous lines.

The next difference is a major one for those who want to run some serious horsepower levels. As it turns out, the spark plugs are finally changed--for the better, the only problem is that the aftermarket has yet to come out with a heat range colder in the new style plug. Stock spark plugs are okay up to the 100 hp hit of nitrous. Above that, the plugs need to be one heat range colder and non-platinum. The '05-'07 cars used a unique plug end, which is patented, and only two companies we know of bought into the patent--Brisk and Autolite. The end of the '05-'07 plug is squared off, creating a difficult way to re-gap the ends as well--another critical modification required when running large doses of nitrous, or big boost. Some of the blower manufacturers sell a tool to crush the end in order to re-gap the plug. The new '08 spark plugs are different and offer a traditional strap, but the aftermarket has not ramped up production in a variety of heat ranges and non-platinum styles. Brisk Spark Plugs should have '08-style plugs available by the time you read this. Spark plugs and the mounting location are the only differences between the '08-'09 cars and '05-'07 models.

The installation is as ordinary as any kit, save for a WOT activation box. Remember we mentioned earlier that the complex electronics required some new components? The S197 Mustangs use a drive-by-wire throttle body, so the normal activation switch mounted under the throttle blade lever won't work. In traditional applications, when the blade goes WOT, a simple micro-switch is tripped and the nitrous and fuel solenoids are opened. There isn't an external throttle blade lever on the S197 throttle body. Nitrous Pro Flow developed a box that is wired into the throttle position sensor (TPS). A process is used to sync the box with the TPS and learn the WOT position. No need to worry, there are a few simple steps to follow that include pressing a button and going WOT with the pedal.

Adding a nitrous kit is only half the story, as we decided to add a few more nitrous accessories. We picked up a bottle heater, which is from Nitrous Pro Flow as well. The bottle warmer wraps around the bottle and heats it up, safely. This product is particularly useful in cooler areas around the country. But what good is a bottle heater if you don't know the bottle pressure? An Auto Meter gauge was installed in the cup holder using a Speed of Sound gauge panel. We picked a Cobalt gauge--the blue glow is cool at night. This particular Speed of Sound panel is a custom piece, but the company can build it to order if you like the setup. We wanted one gauge, so the cup holder isn't rendered totally useless. Speed of Sound added three switches to go along with the single gauge hole. The switches control the bottle heater, nitrous system activation, and purge--which was another item we picked up.

The installation took just a day, and when we showed up, shop proprietor, Dan Carlson, had a fancy new billet bracket for the nitrous bottle. The Real Speed bottle bracket offers a solid mount with minimal cutting of the carpet. The brackets also feature a rubber liner to secure the bottle tightly and not scratch it up in the process. The brackets mount in an NHRA-legal manner, meaning they have 9/16-inch bolts holding them in place. It also has a bracket to hang a wrench for use on the nitrous line. The test subject, an '08 Mustang GT, had four modifications--despite being only a few months old. Real Speed added a Pro 5.0 shifter, FRPP mufflers, Steeda cold-air kit, and a custom Real Speed tune. Real Speed techs, Rob DeMartinis and Dan Mulholland, handled the installation while Carlson tuned the car on the company's in-house Mustang Dyno using SCT software.

Due to the stock spark plugs, we only tested the 100 hp and 75 hp power levels. There are those who have gone up to 150 hp with the stock spark plugs, but we didn't feel comfortable running that much nitrous with the factory platinum plugs. We have two sets of naturally aspirated results; the reason is that the car was overpowering the clutch when Carlson hit the engine with the 100 hp load of nitrous. This was due to the low 3.31 gears out back. Had there been higher numerical gears in the rear, it wouldn't have loaded up the clutch as hard in Fourth gear. Carlson's solution was to conduct the test in Third gear with the 100hp hit.

Naturally aspirated, the '08 Stang threw out 273 rwhp and 278 rwtq--remember this is on a Mustang Dyno that reads lower than a DynoJet and even lower while running in Third gear. The Nitrous Pro Flow 100 shot brought the output up to 363 rwhp and 435 rwtq. It showed a 90 hp gain at the rear tires, which works out to be a bit over a 100 hp gain at the flywheel. The 75hp pills were swapped in and Carlson was able to make these runs in Fourth gear. That produced a slightly higher 291 rwhp and 296 rwtq, sans nitrous. On the sauce, Carlson spun the dyno wheels to 360 rwhp and 427 rwtq. That works out to 69 rwhp gains, which workout to 75 hp at the flywheel. Torque gained an awesome 131 rwtq on the 75 hit and a scorching 157 rwtq on the 100 hit.

OK, if you're scratching your head asking, "Why is the 100 hit worth only 3 more rwhp than the 75, overall?" The answer is simple; we charted the gains on the bottle, regardless of the naturally aspirated baseline. We started with lower N/A horsepower and torque readings. If the clutch did not slip in Fourth gear with the 100 hp setting, then the car would have made 381 rwhp and 453 rwhp. The lower naturally aspirated output in Third gear shows how different the engine is loaded in different gears. The 1:1 ratio of Fourth gear will put out more power than Third gear.

Carlson used SCT Live Wire to log and manipulate the ECU tune, which he had modified when the shop added a Steeda cold-air kit to our test subject. He said this about the tune on the nitrous, "the jets supplied by Nitrous Pro Flow were well matched. The low and mid-range rpm was a little lean and the top-end was a little rich. It would be fine as is, but I am picky so I changed the base fuel table in the tune. I richened the low-end and mid-range and got the air/fuel ratio to run consistently in the 11.5:1 to 11:1 range." The car was tuned for premium fuel, in addition to the Steeda cold-air kit, so Carlson removed a few degrees of timing to keep it safe.

On the 100-shot, three more degrees of timing were removed for a conservative overall timing package, due to the stock spark plugs. Carlson did inform us he modified the top-end timing table due to the nitrous flow. "When the system was activated, it was displacing some of the fresh incoming air through the MAF with force fed nitrous. The MAF counts (mass airflow meter voltage) actually dropped a little with the nitrous on. This caused the engine load, which is calculated by the ECU, to be reduced. The engine load calculation was reduced to the point where it dropped down to the next row on the spark table. At that lower engine load, the computer tune calls for several more degrees of spark advance," he states. Carlson used SCT Live Wire to data-log the runs, identify this problem, and solve it.

In just one day, the '08 was more than capable of going deep into the 12s and take on the latest street machines like the Challenger and forthcoming '10 Camaro--due out by the time you read this issue.