A number of relatively cheap and relatively easy upgrades for performance are out there, and one of the more common suggestions is the cold air intake. The principles behind how it works are relatively sound, on paper, but do they actually work?
Cold Air Intakes Boost Horsepower…For Science!
The general principle behind how cold air intakes work is thermal expansion. Before you Google it, thermal expansion is the process where things expand as they gets warmer and shrink as they cool. Essentially, the atoms and molecules that make up an object huddle together and hunker down as an object cools, but drift farther apart and start moving all over the place as it warms. Heat is energy, after all, which excites said atoms and molecules.
Thus, the gaseous form of a substance occupies a greater volume than a solid form of the same substance with the same mass.
It follows, therefore, that cooler air will have a greater molecular density of oxygen than the same volume of warmer air. Since air is ignited in an engine, more oxygen burns in the same space, increasing power and efficiency.
Isn’t science fun?
But do they work?
A cold air intake will work, since the science behind their operation is about as foolproof as it gets. Depending on the layout of your car’s engine bay, installing a cold air intake might get a little tricky, but not by too much.
A cold air intake is a stupidly simple machine. Basically it’s an air filter on the end of a pipe. Usually there’s some bracing so you can bolt it to something. Sometimes there’s a plastic housing. However, that’s pretty much it. The pipe is a little bigger than the stock intake and also longer, since the filter will draw air from an area with cooler air than, say, the air right around the engine.
Simply put, there is no way they won’t work, since the engine will get cooler air. However, the question becomes how much of a boost they will get.
Small but cheap gains
The gains from a cold air intake will be modest, but they will also be incredibly cheap compared to some other performance upgrades. Aspiration conversions, for instance, will run several thousand dollars…for the cheap ones.
An AutoAnything.com article estimates a 5 hp to 11 hp boost; HowStuffWorks and AskMen both report 5 hp to 20 hp. However, the upshot is that getting one is dirt cheap, since cold air intakes can be had for less than $100 in many cases and certainly less than $500 for the high-dollar units. In the realm of performance parts, that’s next to nothing. Installation, once again, is incredibly easy, since you’re not exactly taking off the intake manifold – just replacing the air intake.
Another upside is that your engine will not only get a modest boost in power, but will also – and here comes the science again – be burning more air per ignition. This means that more of the combustible mixture in the cylinders will be consumed, thus increasing efficiency. A few more ponies and a mile or two more per gallon too!