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How effective is a cold air intake?

Cold air intake for 350z

We take a closer look at whether a cold air intake is worth the $

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When it comes to freeing up some horsepower in your car/truck, one of the cheapest methods is to buy a performance intake or filter.  There are a couple of options though once you make that decision.

  1. Replacement high flow performance air filter like the one shown below: (click for larger images)

K&N Replacement filter

2.Replace the entire stock (OEM) intake air assembly with an aftermarket intake and filter in the stock filter location.  See photo below:

BMW E36 Intake pipe tube

3.  Replace the entire stock (OEM) intake air assembly with an aftermarket "cold air" intake system.    See photo below: (click for a larger image and notice the filter behind the front grill receiving a direct flow of air)

AEM Cold Air Intake Miata

So what are the differences and what should we be looking for?

Well let’s start with number 1 above.  A high flow performance filter will go into the OEM location and do exactly the same thing the factory filter did only these filters claim to be less restrictive while filtering the same.  The fact that they are less restrictive allows the engine to breathe through them easier.  This effectively allows more air to get into the engine easier and make more power. 
The same principle of less restriction to intake airflow is the same way how option #2 works above, with the main difference being that the intake tubing (tract) is also replaced to remove restriction that the factory pieces may have caused.  Many vehicle manufactures will have restrictions on the intake in an effort to reduce sound produced from the engine and keep intake noises down in the cabin.  If the owner of the vehicle is more interested in power and doesn’t mind the noise that comes with it, than option #2 or #3 would be acceptable.  This brings us to option #3, the cold air intake.

What makes an intake a “cold air” intake?

A cold air intake is one that is designed to breathe and receives its air from outside of the engine compartment in an area that receives fresh ambient air.  Ambient means air that is at the current outdoor temperature.  These intakes will often be more expensive do to requiring more engineering to manufacturer and requiring more materials to build than a standard intake replacement like that talked above in example #2. 

Is the cold air intake worth the extra $?

Tough answer, as each persons goals are different, but it can be said with certainty that an intake receiving colder air than that found in the engine bay will make more horsepower and torque.  The reason being that colder air is denser, and the more air you can get into the engine, the more power it’s going to make.  Some cars though have fresh air tubes that do an excellent job of getting fresh air right to the filter.  These cars or trucks then would not see as big of a change in spending the extra money to locate the filter out of the engine bay.
Another thing that needs to be strongly considered is the height of the vehicle and where it is driven.  One of the problems with a cold air intake, which locates the filter out front of the vehicle, often close to the ground, is that is has a much greater chance of sucking up water if the driver submerges the vehicle in any standing water.  This might become a problem for some owners that own cars that are extremely low, or for truck owners who often find themselves off-roading in standing water situations.  In these circumstances the intake filter can be subjected to sucking up water into the engine.  While it is a rare occurrence and not easy to do, it does happen.  A quick search on the Internet will show you stories of people sucking water up their intakes and hydro locking the motor.  It should be noted though that in every instance the intakes are usually located at or below the front bumper.  The cars have been lowered to heights where small puddles will now appear like lakes, and the factory lower splashguard has been removed so that an aftermarket body kit can be fitted.  These owners then drive in the rain through large puddles that submerge the intake and are surprised that the engine hydrolocked.  If just a little common sense is taken in the placement of the filter and avoiding standing water than you will have no problems.

How much power can I expect to gain by having the filter breathing cool air?

Again there is no exact number to this.  It will depend on too many factors to even list, but power will be left on the table if the engine is not breathing ambient outdoor air temps.  Also depending on the way the intake is constructed it could also gain power from a “ram air” effect.  Just know that the cooler the air your motor breathes the better.

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