2015+ STi: Cardboard Air Box Test vs No Air Box
We had a customer come in today, that was not sure if the Cobb Air Box for the Cobb SF Intake made much of a difference, versus not having one at all. So we got to tuning the vehicle and started noticing we were down on power by quite a bit from our initial pulls, so we began investigating.
We looked a little closer at our datalogs and noticed the intake temps were reaching about 70-80 degrees Celsius (158-176 degrees Fahrenheit), near the end of the dyno pull. When intake temps start to go this high, there are compensations in place to scale back on the wastegate duty cycle (lowering boost) and timing values. How much of an affect it actually had is hard to say, but we know it was not ideal by any means.
We decided this was a perfect time to make our first intake box made out of cardboard. With a simple cut and bend, we encapsulated our intake with a pseudo air box. This would allow the intake to draw the cooler air it needed from the fender well, versus directly from the radiator fans that are spewing hot air. The new intakes temps dropped to 45 degrees Celsius (113 degrees Fahrenheit) by redline.
Low and behold, because of the cooler temps we increased power by 15 horsepower, with not a single change to the tune! It goes to show you, if you want an intake make sure it has an intake box to keep the hot air separate from the cool air that should be entering the engine.
We now offer cardboard box intakes for sale with a special introductory price of $2.50 + tax. Local pickup only, installation not included. When the empty box arrives don't fret, the box is all you need! ;-)