Wayne Cook
January 1, 2009

Tech | Nitrous Combo
We were more than intrigued when we first laid eyes on this new nitrous and cold-air induction combo. Made for '05-and-newer Mustangs, the kit is offered by Granatelli Motorsports. The Granatelli name has been synonymous with high performance for a long time, and we are always interested in anything this company might come up with. Everyone knows that a cold-air kit is an economical way to pick up some easy horsepower, but beyond that, adding extra power becomes more complicated. Serious power-adders, such as a supercharger or turbo, add cost and complexity in a big way. Nitrous oxide is clearly the answer for the enthusiast who wants a serious power gain on demand without the added expense of a sophisticated engine or exhaust-driven power-adder.

This photo introduces us to the new Granatelli Motorsports Cold-Air Nitrous Oxide kit. The heart of the system is the inlet pipe, which is an excellent, quality aluminum casting. It comes with the nitrous and fuel spray bar already installed and ready to go. The fuel and nitrous solenoids are positioned opposite each other at the ends of the spray bar. The open-element air filter is a low-restriction unit that can be cleaned and reused rather than replaced. The carefully shaped air-cleaner enclosure fits the car exactly and will isolate the air inlet from engine heat for a cooler charge. Below the air cleaner element is the GMS air meter calibration adapter. It plugs in line to the air meter, and that's all there is to it. No computer reprogramming is required. The 10-pound nitrous oxide bottle comes from Nitrous Supply and is included in the kit, as are all steel braided -4 lines and the bottle mounting hardware. The MSRP for the kit is $1,199.

The downside to nitrous oxide is the fact that you have to refill the bottle after a few passes. However, think about how often you really need that extra kick. We have a normally aspirated Mustang GT that blows the doors off of most of what's out there with ease. However, when we come up against something more serious than a Honda with an exhaust tip, such as a Corvette or Porsche, it would be nice to have a little something extra. The Granatelli Motorsports kit is great because you get the benefits of the cold-air system at all times, including improved fuel economy, and a good-sized battle ax hidden for emergency use. We loved the concept and looked forward to seeing it installed and dyno-tested firsthand.

George Boskovich is a noted Mustang enthusiast with a taste for exotic Ford hardware, such as Boss 429 Mustangs and 427 FE SOHC engines. George also has a beautiful '06 Hertz Shelby GT, and he was kind enough to offer this valuable car for our testing. The great-looking Shelby is No. 500 of 500 Hertz Shelbys produced that year, so it's an interesting subject vehicle as well as the last of its kind. Follow along with us as we travel to Granatelli Motorsports in Oxnard, California, where we'll baseline the Shelby on the company's new Mustang dynamometer. We'll then install the Granatelli cold-air/nitrous oxide setup and see what the kit alone is worth versus the Ford Racing cold-air kit found stock on the Hertz Shelby. We'll then run the car again using a 100hp shot of nitrous oxide and see just how much extra power the giggle gas is worth.

Dyno Results
Before we began the installation, we baselined the '06 Hertz Shelby in stock condition.

RPMTQHP
2,40016574
2,800198116
3,200210124
3,600219151
4,000232180
4,400244194
4,800237221
5,200230233
5,600219239
6,000210234

The Shelby has an automatic transmission, so the figures are a little lower than they would be with a manual transmission car. Remember also that these are Mustang dyno figures and not from a Dynojet. The figures were rounded to the nearest whole number by the software. Next, we ran the car with the GMS cold air in place and reaped the following.

Photo Gallery

View Photo Gallery
Carefully slide back the red lock tab and then squeeze the factory plug to pull the mass air meter connection off of the sensor. Pull on the connector itself and not the wires.
RPMTQHP
2,40017079
2,800221118
3,200227140
3,600238171
4,000251192
4,400257216
4,800242228
5,200238242
5,600229246
6,000216250

To our surprise, the GMS cold air was worth 13 lb-ft and 11 hp. That's a nice improvement, and we suspect it's due to the smooth contours of the Granatelli inlet tube. Now it's on to the big test-the nitrous oxide pulls. The laughing gas comes on at 2,100 rpm and signs off at 6,000 rpm.

After loosening the clamps at the throttle body and the fasteners at the air filter enclosure, the whole OE air inlet assembly can be removed.
Dyno Results
RPMTQHP
2,400275133
2,800303165
3,200309192
3,600328230
4,000380295
4,400415340
4,800401371
5,200371385
5,600360390
6,000348391

The results show that the nitrous is worth a lot of extra horsepower, 141 to be precise. The torque gain was also substantial at 158 lb-ft. Why the extra 41 hp with the 100 hp jet? We wondered and first thought they might have installed the wrong jet. Then we remembered that, after filling the nitrous bottle, it stood outside in the hot summer sun for hours until we were ready to make our pulls. Of course, a bottle not preheated would produce less horsepower and, to get consistent dyno pulls or quarter-mile runs, the bottle temperature should be kept constant. We did not utilize a pressure gauge on our nitrous bottle, but it would be a wise investment for any nitrous install. All things considered, the GMS Cold-Air Nitrous Kit is a good bang-for-the-buck value that we'd recommend.

Photo Gallery

View Photo Gallery

Photo Gallery

View Photo Gallery