Most car magazines and websites are riddled with ads that promise “20% more horsepower” from a cold air intake. That sounds tempting, and installing one is about as complicated as microwaving popcorn. All you have to do is replace that restrictive factory airbox with a free-flowing tube and air filter, then viola! More power, torque, and better fuel economy! But of course, nothing is ever that simple.
How are cold air intakes supposed to work?
The idea is simple really. Cold air has more oxygen than warm air, so if you feed a high volume of dense air into the engine, it will theoretically be able to make more power from a smaller amount of fuel. On paper, this works beautifully. But there are issues that most cold air intakes don’t address, and that can actually reduce horsepower and fuel economy.
Modern vehicles rely on a bevy of sensors in order to operate efficiently. If you change the volume / quality of the air going into the engine, the computer is going to misjudge the application, then adjust the fuel/air mixture to compensate. This will cause the engine to make less power and run poorly. Installing a cold air intake often requires a computer “reflash”, in order to take advantage of the additional air.
Beware of cold air intake kits that claim to “fool” the air sensors with narrow tubes and other trickery. The guys that designed your car’s computer system are probably a lot smarter than the guy who designed that tube.
Your vehicle’s factory airbox encloses the filter element to protect it from the high temperatures inside the engine bay. The opening / air inlet is typically located in a place where it can draw in the coolest air. Sure, the quantity of air isn’t amazing, but the engineers that put it there, did so because it was probably the coolest spot under the hood.
Most cold air intakes aren’t very well shielded from the intense engine heat, causing them to draw in heated air from under the hood, which then heats any cool air already in the system, effectively defeating the purpose of the system.
Turbulence is another power-robbing problem caused by many aftermarket cold air induction systems. All of those bends in the induction pipes can cause the air to swirl around inside the tube. This causes the airflow going into the fuel injection system to be inconsistent, triggering the engine control module (ECM) to constantly adjust the fuel/air mixture. Needless to say, the engine will run rough, and not create the kind of power that it did with the stock induction system.
Are all cold air induction systems useless?
No. In fact, many of the cold air intake systems offered by the automaker’s performance division (Mopar, Ford Racing, Toyota Racing Development – TRD, etc.) can actually increase horsepower and torque. These systems are designed by factory engineers, and they take into account things like filter placement and turbulence. But you may still have to reprogram the ECU in order to see any performance gains. To see if a cold air intake will provide your vehicle with any noticeable performance gains, simply follow these steps:
1 – Locate a chassis dyno in your area and schedule an appointment.
Although your Butt Dyno may feel accurate, nothing beats having actual numbers.
2 – Set a baseline
Begin by testing the power output of your vehicle with the factory airbox installed. This will tell you the current amount of horsepower that’s going to your drive wheels.
3 – Measure the temperatures
Most chassis dynamometers will be able to measure the temperature of the air being drawn into the motor (inlet temperature). You’ll also want to measure the temperature of the air on the outside of the vehicle using a high quality digital thermometer.
4 – Install a cold air intake and test the horsepower again
Obviously, this will tell you if a cold air intake will do your engine any good. But pay attention to the air temperature difference between the two systems. More often than naught, the factory airbox will be a few degrees cooler because of its strategic location.
Unless you see at least a 5-10% increase in power, it’s not even worth leaving the cold air system installed. The reason being, many cold air intake systems (depending on their design) can actually allow water into the fuel system, causing the engine to run poorly. This can also lead to expensive internal damage.
If you really want to improve the airflow to your engine, buy a high quality performance OEM-style air filter, and use that in place of the stock paper air filter. These usually allow more air to flow, they’re reusable, and you’ll be able to enjoy the reliability of the heat/water-resistant factory air intake system.
Source: Mighty Car Mods