Air Intake System Explained

Air Intake Explained
Pre-Introduction:

 

If you’re in the market to buy an aftermarket-intake for your vehicle, K&N often runs specials/deals for many of their products. In addition to that, they guarantee increased horsepower with all of their intakes as well as a 100,000 mile warranty. It’s quite likely the next intake you purchase from K&N will be the last one your vehicle will ever need.

If you prefer a wider-selection of intake brands, Amazon has a huge selection of aftermarket-intakes from AEM, Volant, Injen, Geuine Mopar, Spectre and many more.
Increase your vehicle's performance and horsepower with a K&N intake system
(The links above are affiliate links in which we will earn a small monetary-commission should you purchase something from either Amazon or Knfilters.com. If you do so, you’re helping to keep us up and running! These links open in a new window as to not disrupt your reading here.)

Aftermarket Intake Introduction:

An aftermarket air intake is designed to replace your stock air intake system. The benefits in doing so are well worth the expense. Typically, aftermarket intakes are reasonably priced and requires minimal “know how” to handle installation on your own as opposed to other modifications. Reading the following article, you’ll learn everything you’ll need to make your next aftermarket intake purchase!

When choosing an aftermarket air intake, you’ll want to be sure to make the right choice for your vehicle. While most intakes produce the same results, if you favor one result over the other, you’ll want to know what kind of intake is best for the outcome you’d like.

Most intakes function and aim to produce the same result with only one exception. Later in the article, we’ll go through and explain the different types of intakes available on the market today and how they function. We’ll describe the pro and the cons of each and how they differ from one another.

Lets start by describing what a typical aftermarket intake does, or rather, what the average person is looking to get when buying a new intake. Typically when someone buys a new air intake system, they’re looking to either increase horsepower, increase torque, increase fuel mileage or all three.

What an Aftermarket Intake Does:

Basically, an aftermarket intake is designed to allow more air to flow through your engine. In most cases, the air pulled in from the air- intake is cooler, more dense and more oxygen rich than the air pulled in from a stock (OEM) air intake. The one exception to this rule is known as a Warm Air Intake which we’ll cover later. All aftermarket intakes are extremely efficient in filtering dust and other small contaminants from entering your engine.

So what purpose does colder more dense air serve?

Colder air contains more oxygen which in turn allows for faster/more efficient burning of fuel. When air and fuel meet within the internals of your engine (Combustion Chamber), the ignition of fire occurs and allows for each piston to be forced back down at a greater force thus increasing power output to the wheels of your vehicle.

Also, because an aftermarket intake pulls in colder air, fuel is more efficiently burnt…this results in less fuel needed to power a vehicle. Warmer air is less dense or thinner in oxygen which results in poor performance as well as less gas mileage. Many changes to compensate for greater air intake are taking place within the ECU(computer) of your vehicle; Adjustments are made on the fly to allow more or less fuel to be spent gauged on the temperature of air flowing through your engine’s combustion chamber. One area this information is relayed from is your vehicle’s Mass Air Flow Sensor.

If less fuel is needed for injection then that fuel is reused…ultimately allowing you a few more Miles Per Gallon.

Below, we’ll be covering the following air intake systems:

And other Information such as:

Because it’s the most popular air intake system purchased, we’ll begin this guide with explaining everything you’ll need to know about the Cold Air Intake; Also known as Cool Air Intake or CAI (Cold Air Intake).

AEM 21-478WR WRX Cold Air Intake installed

A Photo of a Cold Air Intake installed away from the engine-bay

How a Cold Air Intake Works:

Each aftermarket cold air intake from any reputable manufacture is thoroughly researched and tested for every vehicle it’s available for. Because of this, these types of intakes cost more than others such as the Short Ram. Well designed CAIs are built using aluminum tubing that stretch outside of your vehicle’s engine-bay.

Often times, as far down as the bottom of your bumper or generally as far away from your engine as possible to reach the coolest air possible. The aluminum tubing is crucial. Most popular brands (K&N, aFe, Injen, AEM, Spectre) equip their many of their intakes with aluminum tubing as it cuts down on heat coming in contact with your intake. This is turn doesn’t allow for “Heat Soak”.

  • Heat Soak – When excessive engine-bay heat causes the tubing(leading from the intake filter to your throttle body) of an air intake to become so hot that it raises the temperature of the air allowed into your engine thus significantly reducing performance.

So long as your engine is running at its normal temperature, heat soak will not be an issue.

Some Cold Air Intakes even come with their own Heat Shield or Heat Shield Box. This isn’t the most popular way to go though. It’s not a bad idea by any means, but the majority of CAIs do not come with these things.

Both of these components serve the same function.

  • Heat Shield –  Is just that. This partially cuts off the intake filter from the rest of the engine, kind of putting it in its own cubicle per say. This is an excellent method for reducing heated air to your intake
  • Heat Shield Box – Serves the same function as a Heat Shield except that the air filter is in its own enclosure, completely sealed off from any outside heat.

There are many debates on which work better. Shortram.com finds that a heat shield is sufficient enough to provide the desired results.

Benefits of using a Cold Air Intake:

  • Provides the most horsepower to your engine as opposed to other intake methods
  • Not as likely to be affected by your radiator fans kicking on which can be an issue with other intakes as they suck in the circulating air from fans. Cold Air Intakes, if located far enough away from this area, don’t have to worry about it.

Things to Consider:

  • Is the toughest to install, requires some technical knowledge
  • Is the most expensive option

If you’re willing to get your hands a bit dirty and have the funds to do so… a cold air intake will be the best option for increasing horsepower and torque in your vehicle. Some intakes claim to boost power up to 30-40 HP. That’s a massive increase.

Here’s an example of the sound you’ll get with a typical CAI:

How a Short Ram Intake Works:

Like a cold air intake, a short ram aims to increase horsepower, torque and fuel economy. There are a few major differences however.

A short ram intake is:

  • Located close to your engine
  • Typically has wider piping than a cold air intake
  • Designed to pull in more air at a time than a cold air intake

Short Ram Intakes or (SRIs) are a great alternative to a cold air intake due to significantly lower cost. Short Ram intakes are much easier to install and require the most minimal knowledge when installing. The tubing on a shortram is wider and much shorter than a CAI. The wider tubing allows for the greater volume of air-flow to your engine over that of a CAI.

To recap slightly, a cold air intake works by pulling in cooler more oxygen rich air while a short ram pulls in warmer air but at a faster rate.However, it’s very important to understand that because the intake is located near your engine, the air being pulled in is warmer than a CAI. Warmer air is less oxygen rich and does not allow for a very clean burning of fuel thus power gains with a short ram intake are minimal but fuel economy is increased over that of  a cold air intake.

The majority of short ram intakes to do come with a heat shield. Again, heat shields isolate the intake from the engine reducing the intake of warm air circulated through your engine bay.

Benefits of using a Short Ram Intake:

  • Cheaper than a Cold Air Intake
  • Much easier to install
  • Better throttle response than a CAI due to the increased air flow
  • Better Miles Per Gallon than a CAI
  • Usually louder than a Cold Air Intake due to increased air flow

Things to Consider:

  • Minimal horsepower gains
  • Produces less torque than a CAI
  • Likely to pull in warmer air
  • Usually louder than a Cold Air Intake (depends if you like the suction noise or not)

Even with the cons, a ShortRam Intake is a widely used, popular option for any gear-head. Unless you specifically need more horsepower, a Short Ram can stand up to a Cold Air just fine.

Here’s an excellent example of the sound you can expect to hear with a Short Ram Intake:

How a Warm Air Intake Works:

A warm air intake functions the same way as a Cold Air and Short Ram intake. A Warm Air Intake or (WAI) forces air into the engine. Can you guess the major difference between the others though? If you guessed “It pulls in warm air” You guessed correctly. A Warm Air Intake looks very similar to that of a Short Ram Intake.

Why in the world would you want to suck warm air into your engine?

The short answer:

  • Better fuel economy
  • but less everything else, throttle-response, acceleration, horsepower and torque

The long answer:

  • Due to the loss in performance, Warm air causes you to open the throttle more. Basically, the same amount of fuel is being spent. However, because the throttle is open to a wider extent, your engine does not have to work as hard to draw the air into it effectively reducing pumping losses in turn making your vehicle slightly more fuel efficient.

The longer answer:

  • The main function of a Warm Air Intake is to decrease the amount of oxygen used with fuel during combustion. Warm air from inside the engine-bay is used. Because warmer air is less dense than cold air, there’s less oxygen to burn fuel in. In turn, your vehicle’s ECU compensates by opening your throttle wider to allow more air to flow in, decreasing resistance the engine needs to overcome to allow air in. What this allows, is for your vehicle’s engine to intake the same amount of oxygen burning the same amount of fuel to produce the same amount of power but with less pumping losses which boosts fuel economy though at the expense of top-end power.

Because most of you are wondering what “Pumping Losses” are, I’ll explain briefly:

    • Pumping Losses – The loss of power from pumping air around in the internals of your engine and its ancillaries, taking away power needed to the wheels. Usually generating excessive heat inside the engine when excess heat isn’t wanted.

Benefits of using a Warm Air Intake:

  • Increase in fuel economy over a Cold Air and Short Ram Intake
  • Still sounds good
  • Looks nice

Things to Consider:

  • Performance decrease all the way around (less horsepower and torque)
  • Throttle response isn’t as responsive
  • Acceleration isn’t as noticeable

Here’s a video comparing a WAI to a CAI in two same brand cars each with either a CAI or the WAI installed:

In the end, a Warm Air Intake will boost your fuel economy but not by very much. For as cheap they can be, They may be a decent option during winter months.

Short Ram vs Cold Air Intake: Which is Better?

We get this question a lot. To be frank, it all depends on desired outcome. Below I’ll overview some of the information that we had already covered, much of it is new though. You’ll be able to recite the differences in your sleep!

Short Ram vs Cold Air Intake Differences:

For visible differences, check this Youtube Illustration:

A short ram intake is just that, short. Because of its dimensions, the intake-pipe does not expand a far distance from the intake manifold; therefore, the air-filter stays close to the engine. Cold air intakes have longer piping, and are created to force the air-filter a distance from the engine into a space with colder air, thus the term cold air intake.

As a rule, because the cold air intake pulls-in cooler air, it normally generates additional horsepower than short rams do. Short ram intakes are usually cheaper and simpler to service and install due to the air filter’s visibility whenever the hood is opened. Cold air intakes are longer; therefore, placing the air-filter further away making installation more complicated and consequently, more expensive.

Short Ram Intake:

Short ram intakes are usually manufactured to substitute stock air boxes. Many stock cars include a plastic box and plastic hose linked to the throttle body, or sometimes right to the turbo. A functioning replacement short ram intake basically consists of a hard-pipe designed from aluminum that substitutes for the stock rubber-pipe, and the stock air-box is reinstated by means of an open element air-filter.

Overall, this will give you a decent power enhancement more than stock due to replacing the limited air-box with an open element air-filter, in addition to substituting the rubber hose with an even metal-pipe.

Many quality, valuable, short ram intakes come standardized by design to maintain the stock air-fuel combinations identical to stock as not to throw any check-engine lights. At times, manufactures will not provide a cold air intake when their examination indicates that it does not boost power more than a short ram intake.

Cold Air Intake:

Cold air intakes are manufactured to position the air-filter as far a distance from the hot-engine as feasible. Above all, when a radiator fan starts, it will not propel the hot-air into the air-filter like the majority of short rams.

A few manufacturers design the cold air intake in a way where it sets the air-filter under or within a fender to possibly encapsulate as much cold-air as possible.

When engines let in cold-air, the oxygen is more concentrated, thus creating more power. When intake manufacturers examine the intake, various air filter locations are tested to observe which location is the coolest.

This normally generates additional power over short rams; however, because of the position of the air-filter, it becomes sullied quicker, making it more difficult to maintain and install whenever the air-filter requires cleaning.

Short Ram vs Cold Air Intake Heat Shields-Are they Worth It?

Definitely. If heat shields are available for an aftermarket intake-system, it is often recommended to purchase it. Normally, this permits a short ram intake to generate additional power because it blocks-off a quantity of engine heat from getting to the open element air-filter.

Which Intake has the Better Sound?

Frequently, the short ram intake resonates the loudest since the pipe is shorter and nearer to the throttle-body. Cold air intakes are a bit quieter; however, the sound may not be as deep because of the air-traveling longer distance in the pipe while the pipe acts as an echo. Each provides vehicles with a powerful intense pitch when on the throttle; an undeniable bespoke noise that any aficionado recognizes.

Should Short Ram Intakes with an Air Box be Considered?

A number of manufacturers include intakes that have an aftermarket functioning air-box. This basically has a better flow than the stock-air box and permits air-filters to absorb additional air.

These are excellent for engine-bays that do not permit heat shields and when they have difficulty with the radiator fan passing hot-air near the engine compartment.

Is There Really a Difference When One Intake is Cheaper Than the Other?

Countless people believe that an “intake” is an “intake,” and whichever they purchase makes no difference since they are all alike. However, this is a long way from the facts. Many people purchase inexpensive short ram intakes or cold air intakes that essentially damage horsepower.

The model is basically a pipe with a shoddy filter, and because it has not gone through any testing the design does not guarantee that the air/fuel combination will stay in the correct range to permit a vehicle to benefit from the additional air-flow.

Instead, the computer is forced into defense-mode pulling back timing, which impairs performance.

A well made, high-performing intake will cost more due to the manufacturer investing more time and cost to guarantee when their customers install an intake on their automobile, the model, piping size, pipe length, denseness of the metal, and the superiority of the air-filter is in good standing to carry their trademark.

Air-filters are the key factor. It demands a superb design because of its function; to permit additional air-flow but confine ample or extra grime from entering a cars’ engine.

In fact, it is fundamentally tricky to permit additional air-flow while catching dirt and dust particles. Inexpensive intakes allocate a larger quantity of particles through, that damages engines overtime, block sensors, and bring about a vast number of other problems.

Vs. Conclusion:

Naturally, when you compare short ram vs cold air intake…it depends on what you are looking for from your intake that will determine which one you should choose. Cold-air usually generates more power but is more expensive and more difficult to install. Short rams are less costly, simpler to install, but sometimes produce less power.

Individual needs vary. Some people may prefer the appearance of the short ram intake. Others enjoy the idea of the short ram intake’s louder sound when they are weighty on the throttle. Whichever intake is selected, bear in mind that a quality intake will set the groundwork for any other aftermarket alterations that will profit from a superb flowing intake-system.

Frequently Asked Questions About Air Intake Systems:

Are Aftermarket Intakes Worth It?

Of course, so long as it’s one from any reputable manufacturer. All popular brands such as K&N, Injen, Spectre, AEM, aFe and others conduct extensive research and testing to be sure their intakes out-perform your normally restrictive stock intake system. It most cases, aftermarket intakes are much more efficient at filtering debris before it reaches the internals of your engine.

Do I have to worry about Hydrolock?

Courtesy of Redline360.com:
Hydro lock is usually not an issue, but it can happen in some rare cases. Hydro-lock occurs when your cold air intake gets submerged in water, and your engine intakes water, causing engine damage. This can and has happened in the past, but it’s usually an extreme case. An air bypass valve installs in the middle of your cold air intake, so if this happens to you, the higher pressure of the air coming into the air bypass valve wouldn’t allow water to enter your engine.

Some cold air intakes also convert into a short ram intake, so if you are worried about hydro-lock, we recommend to switch to a short ram intake during raining season or other conditions that may cause your air filter to be submerged in water, or water splashed up on your air filter.

Are “Do It Yourself” Intakes Worth It?

Unless you’re technically inclined and know exactly what you’re doing then no, it’s not worth the risk of  degrading engine performance or worse, damaging the engine.

What is Smog Legal?

Many aftermarket intakes abide by the  CARB (California Air Resources Board) law. For a manufacture to be classified as smog legal, they must have each intake inspected by CARB. These tests are expensive, so not all intake brands are smog certified. Intakes that have been tested and have passed the CARB testing come with a sticker that shows your intake as legal to law enforcement.

Air Intake Comparison

This table should be used as a guide for choosing an air intake based on your personal prefrences
TypePerformanceFuel EconomyInstallationExpenseRecommended For
Cold Air IntakeHighest increase in horsepower and torqueLowest increase (if any) in fuel miles per gallonHardestMost Expensive due to research, testing and longer tubingThose that want to get the maximum amount of power out of their vehicle
Short Ram IntakeLow increase in horsepower and torque but provides decent acceleration and more responsive throttle response over a CAIMore conservative than a Cold Air Intake.Easy Less than a Cold Air IntakeThose that want an easier method for producing minimal power/sound at a cheaper cost
Warm/Hot Air IntakeLowest. Causes a loss in performanceBetter than both a CAI and SRIEasyTypically cheapestThose looking to gain the most Miles Per Gallon from their vehicle at the expense of power

Now that you know the basics of an aftermarket air intake system, you can proceed to Amazon and check out their extensive list of intakes for your vehicle. Or K&N if you prefer.

Also, be sure to share this with anyone looking to learn from the information in this article!

Now that you’ve learned all about air intakes, be sure to read:

Thanks for reading.

-Sean from ShortRam.com

14 CommentsLeave a comment

  • I loose power when ascending when I used short ram intake, the engine got easily shut off during traffic in ascending position, i need to rev up higher just to move forward otherwise the engine shut off.the clutch assembly is not an issue, engine as well, I love the sound, the throttle response, but that is my only problem during ascending. Is it normal? Pls enlighten me. Thank you and more power

    • Hey Alex. There could be a lot of issues that can cause this problem. Have you narrowed down the problem to the SRI? Did you remove the SRI and install the stock intake system again to see if the issue persists?

  • Hello

    I am looking to buy an aftermarket cold air intake for my car.
    Its seems I have 2 interesting options. One is cheaper but the air filter does not seem to be sealed. Can this be a problem?

    Thank you

    • Hey Rick,

      I found this comment on Reddit to prove helpful:

      The resonators in your exhaust tune the exhaust note into something that is not brutal on the ears, along with the muffler, which quiets the whole thing down. Removing the exhaust resonators will just make the car sound worse and louder. Removing intake resonators can result in incorrect MAF readings at the very worst, and more noise at the very best.

      Removing your resonator more than likely won’t be very beneficial. If you’d like to gain more power, you can always do a cat-delete to remove your catalytic converter(s).

    • Hello Franklin,

      Heat soak can cause a significant loss in horsepower. Generally, the warmer the engine/internals and surrounding components are, the poorer your vehicle will perform and the quicker the components affected by temperature will wear. All modern vehicles equipped with a CPU are programmed to function optimally between a specific temperature range so that the proper amount of fuel is given otherwise the timing is “retarded” resulting in loss of power.

  • Curious to ask but I installed an intake and my check engine light came on right away. It’s saying that the air is too rich and I can feel the power loss because of this… any suggestions on how I can fix this issue? I know it’s the intake because it was the doing this before hand. It’s like the car doesn’t understand the new air intake and thus reducing power.

  • I know the warm air is the best for gas mileage and is definitely better than the CAI but is it that much better than the short ram?

    Thanks

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