Does a Cold Air Intake Really Work?
When it comes to making power, the formula has not changed much over the years. More, cooler air = more horsepower. When it comes to attracting views online, the formula has also not changed much over the years. More controversy = more attention. So it is no surprise that after every inquiry about a cold air intake (CAI), there are droves of posters who will claim they make no power. This is of course not to say that all parts make power. In fact, many parts do not. But before we set out to make our intake we wanted to answer this question, and enlisted a local NC Miata on which we were about to do some tuning.
The recipe here is simple. Warmed up before intake dyno, warmed up after intake dyno, PRIOR to any tuning. Our expectations here were modest. We would typically see on average 2-4 WHP on these platforms with the popular intakes that hang way down towards the bottom. AFR was essentially the same on both runs, the factory ECU applies a 15% or so fuel trim (can go up to 25%) after the intake install, putting it right back where it should be. Unfortunately in wet climates, we have done quite a few 2.5 swaps for folks who ingested water as a result. We set out to make a prototype that had larger tubing throughout (2.75"), compatible with the factory MAF by using a MAF body that's just within the factory correction capability, this way there is not a requirement for a retune, but you get all the benefits of more airflow and cooler temps. In addition we ceramic coated the intake to reduce heat soak. The result? See for yourself below.
One of our other goals was to determine how our air filters performed. Unlike other brands, these are all manufactured right here in PA, we were able to custom design a filter with dense pleating that can fit in a very tight applications (such as behind a bumper). These filters are small in size, but if you were to fully unfurl the pleating you would find that the actual filtration surface area is that of filters twice their size. But any restriction is a restriction.
After this test we have created another version (11"x2.75" and 9"x3") that can be utilized to extract every last HP. The standard 8" version can be easily removed and serviced without removing the bumper, the larger versions do require the bumper cover to come out for R&R. One of the other advantages to this dense pleating/high flow media is that it never needs oil, and can easily be washed with soap and water. In addition, the larger the area the less frequent the service interval, the 11" version can go years without service.