Cold Air Intakes, also known just as CAIs, are often advertised as a great way to gain horsepower for a relatively low cost without the need of making huge modifications to the engines.
This subject is always a topic of debate in almost every car enthusiast forum, community, club or gathering, and you will usually find two very opposite positions: people who think that upgrading an engine with a CAI will enhance its performance almost magically and people who are completely against it, purists that claim that you can neither get any benefit from this mod nor get it to deliver the promised results; in their view, CAIs even make your engine lose performance because instead of taking cold air they do all the opposite.
As a car tuner with experience in squeezing engines to the most, I have to say that this matter is not a subject that is open to debate; what is really important here are facts.
The concept of cold air intakes is simple: they are designed to increase the amount of oxygen available for combustion with fuel based on the physical principle that air gets more dense at lower temperatures. Cooling the air that is going to reach into the engine will produce more powerful combustion, hence gaining horsepower and torque.
Other information provided by CAI’s manufacturers is that their kits use less obtrusive filters and have bigger filtration surfaces, which allows the engine to suck up more air. This statement is not quite true. Factory air filters provide enough air for an engine operating under standard conditions to breathe properly.
However, car manufacturers sometimes need to install more restrictive air boxes and filters to meet the contamination standards of every state; that’s why you will find a legend in most kits that will read “for off road use only” or you will find a CARB EO number which will certify that the kit is street legal in the 50 states. Other kits will state that they are not legal for street use in states with high emission controls, as is the case with California.
The issue is that a modified engine will need to consume more air than a standard one but an engine can’t take more air than the one that its pistons sucks during the intake phase, unless the air is being forced into the engine somehow, for example by the use of a supercharger or a turbo. And even in that case, if the car comes factory fitted with one of these, increasing the filter’s cfm (cubic feet per minute) won’t increase the engine’s power unless you make some mods like raising the boost of the turbo.
Are Cold Air Intakes Worth It?
Everything depends on the quality of the CAI, the material of the piping and the location of the filter element. If the filter element is placed in a spot that is receiving fresh air and everything is isolated enough to avoid air being heated by the engine’s heat, then things start to become interesting. If the engine is standard but has big displacement – let’s take a 2016 Camaro with a 6.2 engine- you will gain almost 25HP installing a CAI in it.
If you are installing a good kit in a Jetta VI 2.0 TSI you can expect gains of about 10HP in a standard engine.
On small 4 cylinder normally aspirated engines with low factory power output, installing a CAI kit is not worth the money and time; if you get any power gain at all it will be under 2HP. You will see that many of these kits don’t show any performance charts on the manufacturer’s websites, or they show the dyno charts of highly modified engines.
There are two extra factors that have nothing to do with performance but that are related to personal taste and likes which are sound and looks. Installing a CAI makes your engine sound more aggressive and rough. If your engine is turbocharged you will hear the classic “Fast and Furious” sound of the turbo admission discharge valve. About the looks, good Cold Air Intakes enhance the aspect of any engine.
Many people choose to install CAIs in their cars just because of these two factors; if they get any performance improvement is a bonus for them.
Do Cold Air Intakes Increase MPG?
If the kit comes with a good quality filter element and it’s efficient enough to take cold air into the engine, it will slightly increase the MPG. A less restrictive system allows air to flow into cylinders more efficiently during the induction stroke, making the combustion stronger and more powerful.
Some systems avoid something called “heat soak”, which is what happens when the car is idling without moving. The lack of airflow causes underhood temperatures to rise; a well designed CAI kit will prevent this effect by taking air from the outside of the car.
CAI manufacturers always state that their products could increase your MPG but it’s a question of marketing. When you install a CAI, in most cases you do it because you want to increase your engine’s power. To do so you need your engine to burn more air and fuel at a proportion of 14.7 parts of oxygen to 1 part of fuel, which means that you will need to burn more air/fuel mixture to get more power. Taking this into account, it doesn’t make any sense to try to save fuel and increase your engine’s horsepower at the same time.
Do Cold Air Intakes Damage Your engine or Shorten Its Lifespan?
Everything depends on the filter element’s quality. If the filter that comes with the kit doesn’t filter the air properly, the engine will suck debris and will be prone to suffer internal damage and/or will have its lifespan shortened because of the friction of that particles against the engine’s components.
How Much Horsepower Does a Cold Air Intake Add?
It all depends on the quality of the kit, the engine displacement, if it’s being installed in a turbocharged or a naturally aspirated engine, if it’s a standard or modified engine, the level of tuning of the engine and many more factors. What is certain is that by every 10 degrees that you reduce the engine’s intake temperature you get approximately a 1% power increase. In other words, if you have an engine with, say, 200HP and you manage to lower the intake temperature by 10 degrees you would gain 20HP, but there are a lot of other factors in the equation that make this rule only a simple estimate.
In conclusion, if you are considering buying a CAI kit for your vehicle it’s advisable that you compare the different kits available, analyze what kind of engine you have, how big and tuned your engine is and what is your goal about power / torque gains. If you take the time to analyze all this you will make a good decision and you will avoid being disappointed.