Horse Sense: The cold-air intake market is big business because it's an affordable modification that can reap big gains on a box stock car--especially the '05 Mustang. With nearly 200,000 '05 Mustangs hitting the streets--a reported 70 percent of them are V-8 GT models--this is a super competitive market for cold-air-intake designers and sellers.
As difficult as it is to pull off, we love to do product evaluations of the most likely parts our readers will buy, install, and keep on their Mustang for many years. And no product fits this description better than the ubiquitous cold-air intake. This simple device has one purpose: to get more air into the engine to increase efficiency and therefore allow more horsepower to be generated with a simple parts swap. No car begs to be modified like the '05 Mustang GT with its overachieving 4.6-liter Three-Valve modular engine chugging out 300 hp in factory trim.
As was the case when we compared all available cold-air systems for the '03 Cobra (May '03, p. 170), we are constantly amazed at cold-air intake designers' creativity at getting more air into the awaiting engine. The '05 Mustang is the hottest car in America, and those creative juices were running overtime. Generally, most cold-air systems specific for the '05 Mustang offer a larger conical filter in the general underhood vicinity of the stock airbox utilizing what Ford has already engineered into the car. (We had one obvious exception to this, as you will soon see.) Some kits offer larger-diameter intake tubing as a freer-flowing conduit for the intake charge.
Once you get past the general design of these cold-airs, there is a great deal of difference in materials utilized, price range, and necessary tuning (itself a big cost factor) to make it work with the often-finicky '05 Mustang computer programming. Our goal was to get as many '05 cold-air intakes as we could find; put them all on the same car on the same day on the same dyno; use a scientific testing procedure to see how they stacked up; and report back to you with the goods.
Several of the manufacturers of '05 Mustang-specific cold-air intakes we contacted for this story chose not to participate. Our intent is not to draw attention to them, but we want our readers to appreciate the confidence of the companies that chose to be a part of this 5.0 Mustang and Super Fords magazine test and evaluation.
We contacted MD Motorsports in Cincinnati and outlined our plans. MD is one of the top SCT tuners in the country, and, as such, has access to '05 Mustang software before most shops. In addition, they already had a number of '05 Mustangs on their dyno, tuned them with positive results, and were interested in working on our comparison. The thing that sealed the deal was the pending release of SCT's new '05 Mustang data-logging software (which turned out to be critical in the successful completion of this story), and MD would be the first in the nation to have access to it.
We gathered contact information for the companies producing an '05 Mustang CAI and sent an invitation to participate in the comparison. In addition to formalities, each letter contained the following information on our testing protocol:
"To keep this test as accurate as possible, we will adhere to the following testing protocol: The same car will be used for all testing on the MD Motorsports chassis dyno. Rear-wheel horsepower will be measured in 100 percent stock form. The car will then be tuned to a set air/fuel ratio and set timing level. Each cold-air will be installed according to the manufacturer's instructions. Rear horsepower will again be measured with the cold-air in place with run conditions (coolant temperature, inlet-air temperature, timing, air/fuel ratio, and so on) as close as possible to the baseline pull. All efforts will be made to adjust the air/fuel ratio to the exact same as the baseline run to avoid this variable causing a change in horsepower. This testing procedure will be continued for all of the cold-air systems submitted for the story, which should ensure we have the same weather, car, testing facility, and tuning for equal comparisons."
As one would expect, several manufacturers had questions about our testing procedure. Most told us it would be impossible to keep the air/fuel ratio the same given the funky-smart '05 Mustang computer. And we agreed to a point because of the given variability with the car, weather, tune, computer, chassis dyno, and other factors out of our control. Still, with a solid scientific testing program with state-of-the-art equipment, as well as a skilled '05 Mustang tuner at out disposal, we were confident the task was doable.
Some of our participants didn't want any tune for their cold-air intake. Not only does this flaunt their engineering skills, but it also points out what a cost savings these systems are when a full dyno session with a custom computer flash can cost $200-$500, depending on the hourly rate for your speed shop. We followed these manufacturers' wishes, and have provided rear-wheel horsepower measurements with just the cold-air bolted into position. But we also gave Ken Bjonnes the creative opportunity to see what he could do; so you'll also see a dyno number that resulted from the CAI and an MD Motorsports tune.
Lee Bender of C&L offered an interesting way to verify our system. Since his kit comes with a DiabloSport Predator tuner with a well-tested program already installed, he suggested we install his tune, use the Predator to record timing and air/fuel, then copy that program with an SCT tune-up. Getting a rear-wheel reading from each tune would give us an idea of how much variability there was in the system with respect to the computer changing the timing or air/fuel during a pull. Also, it would reveal how much variance we could expect from pull to pull. The rear-wheel variance was unquestionably the scariest part of this evaluation.
With so much reputation, respect, and money riding on our results, we didn't want a false reading to unfairly judge one of our participants. To that end, Ken made back-to-back pulls that couldn't vary by more than 2 hp. This was quite repeatable with each system, but we still set our variance at a possible 5 rwhp. That's a lot (almost 2 percent), but it's realistic when you're dealing with chassis dynos, computer-interpreted data, correction-factor changes, and weather conditions. From the start of our test to the end--some 10 hours--the temperature rose from 86 to 103 degrees, and the SAE correction factor (used to correct for such weather variations) moved from 1.02 to 1.03.
Our test car was bone stock (with the exception of a ZEX nitrous system you may see lurking in the back of some of our photos). The fuel tank was filled with 93-octane fuel, and our target air/fuel was 12.6:1. Following the above-described protocol, Ken Bjonnes of MD Motorsports set about tuning the car while his partner, Brandon Alsept, and our old friend, Tim Probst, got to the task of installing/swapping the kits.
At first glance, this would appear to be a straight-up horsepower war--but it isn't. The cold-air is an integral part of an entire system and is typically one of the first upgrades on a serious '05 Mustang. Therefore, the cold-air is usually the longest-lived part on the car, so you have to live with it through several stages of buildup. Beyond that, there's much more to the cold-air than how it affects horsepower gains. To add to the value of all this hard work, we wanted to expand on this concept, so we gathered a panel of five judges (made up of a materials engineer, a Mustang racer, a Mustang street enthusiast, a 10-second '04 Cobra owner, and a general hot-rodder) to help us evaluate each system.
We asked our judges to score each system on a scale of 1 to 10 (10 being the best) on ease of installation, value, appearance, overall quality and merit of design, and expected durability. We've included the box scores for each system to better inform you about each kit and how it did in a category more important to you. We cautioned our judges not to influence each other, but we wanted them to discuss each system openly before they voted in case one of them caught something that should be pointed out before voting. As it turned out, the subjective evaluation greatly enhanced our study, as it honed in nicely on the strengths and weaknesses of each system without directly comparing them.
Each cold-air prototype from our participants in the study has been noted. They were labeled as such for our judges so that these early production units wouldn't adversely affect the evaluation.