Cold Air Intakes FAQ

Best Cold Air Intake for 7.3 Powerstroke
Written by Jim Malkovich

What is a Cold Air Intake?


You probably know that a car engine works better during cold weather than when it’s hot outside. The reason is that cold air is denser, packed with more oxygen molecules, and with more of those in the engine cylinders, the fuel is burnt more efficiently, providing increased power and reduced gas mileage. But that doesn’t mean you have to move to where it’s always cold or wait until winter. With a cold air intake system (CAI), your vehicle can provide the ultimate performance the whole year round (well, that’s what they say), resulting in the most satisfying driving experience!

A cold air intake is a system that supplies cold air to the cylinders of an internal combustion engine to increase its power output. The air must be as cold and dense as possible to get the best performance when you accelerate. To ensure sufficient airflow, both complete off-the-shelf kits and DIY options are used for a specific vehicle model.

CAI Parts

  • Cold air intake filter; 
  • Cold air intake tube;
  • Cold air intake heat shield; 
  • Cold air intake bypass valve;
  • Cold air intake vacuum hose;
  • Cold air intake filter wrap.

Cold air intakes are manufactured for individual car brands as well as universal ones. 

A standard intake system is usually highly restrictive to the airflow. This is due to a “tight” pleated paper air intake filter and the manufacturer’s desire to reduce noise. Besides, the air is usually sucked in from a hot engine bay. The air is so hot because it’s taken from the underhood space, plus there are heated plastic elements located close to the engine. All this reduces the engine power. All CAI systems draw air from the outside, and it’s, obviously, colder.

Basic CAI Operation Principles

  • The air is supplied to the engine from the coldest places;
  • Maximum filter-engine distance;
  • Smooth (not corrugated) intake tubing to avoid airflow restriction;
  • The shortest possible and most distant from the hot engine parts intake filter-intake manifold duct;
  • Heat-resistant materials utilization.

What Does a Cold Air Intake Do

Mainly, a CAI provides cold and dense air to your engine. You can also notice a little (5-20 HP) horsepower increase along with torque and throttle response improvements. If you mix it up with other engine modifications (a new free-flowing aftermarket exhaust system, for instance), you will get a MUCH more efficient system. 

When mixed with fuel, the air (oxygen) turns into a better combustible blend (air/fuel mixture of a perfect ratio), which helps the engine burn the fuel more efficiently, resulting in increased HP, torque, and less toxic emissions. 

Basically, a CAI is a “medicine” for your engine that makes it function at full efficiency. You can call it one of the possible modifications to improve the performance of your engine and add some a few horses or an aftermarket assembly of parts that allows your car’s internal-combustion engine to fully “breathe.” You are supposed to hear that amazing sound of free-flowing cold air into your engine once you install the product.

CAI Benefits

  • Increases engine power – adds a few more horses and more torque.;
  • Provides faster turbocharger start;
  • Reduces detonation risk;
  • The engine does not stall in hot weather, runs nice and smooth;
  • Improves throttle response and reduces fuel consumption;
  • Aggressive engine sound. A CAI is designed to improve performance by sucking in an increased amount of air, which results in a deep, throaty growl that many auto-enthusiasts appreciate so much;
  • Extended engine life. An engine with a high-quality cooling system will last longer because it lets it breathe properly. Plus, a CAI system will also help your radiator;
  • It can be customized to complement the look of your engine bay;
  • Modern cold-air intakes are manufactured in various sizes, colors, and different tube finishes (black, chrome, polished aluminum, silver, copper, powder-coated, or gunmetal gray). Some of the intakes even have paintable surfaces for customization. However, make sure the paint applies to the chosen tube material in advance;
  • It can be installed relatively easily with standard hand tools. There are individual models for perfect fitment.
  • Less toxic emissions.
  • Improved reduction of airflow restriction.
  • An intake filter does not choke on the motor by letting in more airflow;
  • Colder air enters the engine (compared to the air in the engine bay);
  • More oxygen in the air (as it’s cooler).

CAI Cons

  • Typical filter-produced noise. Many drivers like it, though;
  • Hydraulic impact probability in case of extreme installation methods and vehicle operation.

Cold Air Intake System


CAI filters protect the engine from various contaminants. It’s usually located in the upper wheel well area, or beside a fender where it can suck in cooler air, less heated by the engine.

The air may contain numerous contaminants like soot, pollen, dust, dirt, leaves, bugs, and various particles. Some contaminants can be abrasive and cause excessive wear of engine components, while others can clog the system. CAR filters can be dry and oiled, washable/reusable and disposable, with paper, synthetics, or cotton gauze filtration media. 

Dry, non-oiled intake filters are often made of paper/foam for ultimate filtration performance. These filters are usually disposable, but can also be washable/reusable. Dry intake filters catch up to 99% of the incoming contaminants and are more popular among truck drivers and off-road racers due to their powerful filtration, ease of use/maintenance, and durability. However, they are more restrictable for airflow, which is not beneficial in terms of fuel economy.

Pre-oiled filters are often cleanable/reusable, they feature a thin layer of oil (typically, around 80 grams of oil) and capture about 98% of contaminants. The oil’s viscosity and its sticky ability are significant factors when it comes to trapping various contaminants. These filters also provide slightly better airflow than dry filters.

However, they must be properly cleaned and oiled regularly; otherwise, they may cause problems for the engine or damage the MAF sensor (if over-oiled). 

The filtering component material is usually multiple pored layers of cotton gauze or synthetic media. Filter layers with larger holes (oiled filters) typically capture most of larger particles like insects, stones, and leaves, while micro-pored layers catch the finest particles of dust, dirt, and pollen.

Typical air intake filters capture around 80-90% of contaminants down to 5 microns is about the size of a red blood cell. Premium air filters provide better filtration and have more layers of progressive media, increased holding capacity, and larger filter surfaces that capture from 95% to 98% of particles down to 1 micron in size. Such filters also have a longer service life.

A cold air intake heat shield/housing is a powder-coated/polished aluminum (typically) airbox or sheet, a thermal barrier that protects the air filter from engine heat by dissipating it. The unit actually re-radiates out much less heat than it takes in, helping the intake filter suck in cooler and denser air for improved combustion, more HP, and better overall engine performance. You can also have your heat shield gold plated (gold is known to be the best material for heat shield) or add heat resistant fabric to the shield.  

A cold air intake bypass valve provides a vacuum leak to avoid the air filter when the intake filter sucks up some water. Air bypass valves are usually mounted onto the intake tube.

A cold air intake vacuum hose is a silicone (typically) accessory, which is the vacuum feed for the PCV valve, the air intake line for the PCV (Positive Crankcase Ventilation) system. The hose is connected to the intake, which, when under vacuum, will pull air through the crankcase to remove any corrosive and fuel vapors. The hose draws in filtered air from the intake.

Cold air intake tube is a large high-density composite (high-density plastic), metal (aluminum, steel, stainless steel), silicon, or carbon fiber smooth pipe with less bents (compared to factory air intakes) that allows for more airflow into the intake system by drawing larger amounts of cool/dense air from outside, resulting in better engine performance. This part of a CAI is usually located in the proper engine bay area (e.g., a fender, grille, hood scoop) where it can suck in air from outside the bay. Intake tubes can be manufactured in various shapes, e.g., mandrel-bent, curved- or U-shaped, etc. for a perfect fit. 

Cold air intake filter wrap is a filter cover that extends filter service life and improves performance by capturing most of the airborne debris before it gets to the filter media.

Tube Material

The difference between metal and composite CAI tubes is mostly aesthetical (and the cost too). The thermal conductivity of the tube material has little effect on engine power. However, many will say that composite tubes are better since they don’t absorb and then retain heat for a long time, unlike metal tubes do. The thicker the tube material, the more the heat is retained. But metal intake tubes, however, are the ones that make that WOW factor, which means a lot for some car enthusiasts (especially for those involved in car shows and street racing). 

Whatever you choose, before you purchase a cold air intake system, make sure you know everything about the tube materials concerning your vehicle model. 

Aluminum

Aluminum tubes are better at friction resistance to air than plastic tubes. It will not distort because of engine heat and will retain it’s sleek look and shape for a long time. However, metal is known to absorb heat fast and then hold it for quite a long time resulting in the heated incoming air, which is not beneficial for the engine. Moreover, aluminum tubes can get scratched very easily. Still, it all depends on material quality. Thin-walled aluminum tubes will dissipate the heat much faster than plastic tubes, as air is moving. Aluminum cools faster than steel. And then there’s also a better look and sound than plastic tubes can provide.

Polyethylene plastic

Polyethylene plastic (composite) is an excellent blend of lightweight flexibility and ultimate durability which can even be found in some bulletproof vests, which means it can withstand the most rigorous conditions in your engine bay. It doesn’t retain heat the way metal tubes do and doesn’t heat up as much, resulting in cooler air entering your engine. The molding process of composite tubing allows for accurate bends for more airflow and improved power.

Stainless steel

Stainless steel tubes are way heavier compared to aluminum tubes. However, stainless steel tubes don’t conduct heat as much as aluminum tubes, have better corrosion and deformation resistance, and are easier to maintain. They also have better welding capabilities. And then there’s, of course, a better, shinier look and more aggressive sound.

Carbon fiber

Carbon fiber air intake tubes can boast with lightweight, sufficient temperature control (heat reduction abilities), and rigidity. They are great for heat resistance, but the prices are usually quite high, though. These tubes provide increased airflow and a more significant impact on resonance (just like stainless steel tubes). CF resists power-robbing engine heat and delivers an unrestrictive path for cold and dense airflow.

Silicone

Silicone tubes are more flexible than other tubes. They create less stress on other parts and help cut heat drastically. The sound will get a bit louder, but not as deep/throaty as aluminum tubes can provide. Some silicone tubes are also covered with carbon fibers, which is simply an aesthetical matter. Apart from that, there’s almost no difference from composite intake insulators, except for the higher price. Some drivers also claim they do not transmit induction wave pulses as good as composite or metal tubes (heat conductors). Plus, there can be some mounting issues.

Filter Media Material

Just like with cold air intake tubes, the situation with filter materials is approximately the same. The differences in performance and abilities are rather minimal. However, some filters get clogged faster, and some can’t capture fine dirt particles. In the end, it all comes down to how tightly weaved is the media of the filter. Tightly-woven filters will capture more dirt but provide higher airflow restriction, while loosely-woven filters will allow more airflow through along with more airborne contaminants. So it all depends on your personal preferences and, of course, what’s available for your car.

Paper

Paper intake filters are most standard OEM models made out of pleated wood pulp bonded together. Their (typically, non-screened) media is quite rigid, which keeps the filter from collapsing. Some manufacturers claim their paper filters are less restrictive and have more pleats, which is a good thing because the larger filter surface will allow more air through and capture more dirt particles. Such filters are quite cheap, but they do their job well.

However, paper filters may get clogged fast and will need a replacement for adequate efficiency. High-quality paper filters will surely last around 10.000-20.000 miles (around two years).

Cotton gauze or synthetic

Cotton gauze or synthetic filters are the most popular (K&N). Some manufacturers claim their filters provide power increase; however, in reality, the benefits are often quite modest, if any. Cotton filter media layers are often tightly pressed between aluminum mesh and pre-oiled so that any dirt particles that go through the filter will get trapped due to the oil’s viscosity feature. The pleated gauze media of such filters often have bigger holes for better airflow and ultimate filtration. These filters often provide typical induction noise to change your driving experience. And sometimes, that may be the only change you will notice. They are often washable/reusable and need no replacement if properly cleaned/maintained and oiled in time. Just make sure you don’t over-lubricate the media because this can lead to some problems with the airflow sensor. 

Foam

Foam filters are much like cotton and paper filters but less restrictive. The difference in their performance is so minimal that, unless you live in a dusty climate, you will hardly notice any. However, they will get clogged up easier than paper/cotton filters due to the lack of surface area and dirt holding capacity. Dirt particles are often stuck on the outside of the foam and block the openings/foam cells, creating higher vacuum pressure, which makes dirt particles penetrate deeper into the filter. So the airflow is reduced as well. These filters are often manufactured with wire meshes to keep the shape of the filter.

Metal

Metal intake filters are very rare. Made from stainless steel mesh layers, they look cool and don’t need to be oiled, but their efficiency is doubtful. This is a clear example of the for-the-looks case. They have large holes in their filter material and are less restrictive compared to the filters above, which, in turn, tells about their low filtration capabilities. Such filters are popular among car show participants that often have no intake filters at all since they don’t ride their custom and expensive cars that much.


CAI FAQ


How much HP does a cold air intake add?

Horsepower gains may vary, depending on specific vehicle configuration. The average CAI bonus is around 5-20 additional HP.

How does a cold air intake work?

Mainly, a CAI provides cold and dense air to your engine. You can also notice a little horsepower increase along with torque and throttle response improvements. However, if you mix it up with other engine modifications (a new free-flowing aftermarket exhaust system, for instance), you will get a MUCH more efficient system. 

When mixed with fuel, the air (oxygen) turns into a better combustible blend (air/fuel mixture of a perfect ratio), which helps the engine burn the fuel more efficiently, resulting in increased HP, torque, and less toxic emissions. 

What does a cold air intake do to gas mileage?

Supposed to improves it. Your engine needs the proper volume of oxygen for burning fuel. Otherwise, fuel consumption will be increased, and that’s when a CAI enters the game. The system guarantees optimal air/fuel ratio to provide advanced fuel economy.

What does a cold air intake sound like?

Depending on materials and your vehicle modifications (turbocharged cars or those that use 3-4 valves per the cylinder will get quite loud with a CAI), CAIs can provide a pleasant air-sucking-in sound. 

Depending on your exhaust system, a CAI can make it sound louder – the more air in, the more exhaust out, subsequently, the tone is changed for throatier (under throttle). Long and short intake tubes can provide a deep and throaty sound. That’s typically the case of aluminum/stainless steel intakes.

How to make a DIY cold air intake?

You can make a tube from special multi-purpose pipes, or take an aluminum household pipeline and bend it in certain areas, and then connect everything with steel clamps. Then you should make air and locate it outside the engine bay. The easiest way is to take the aluminum tubing directly from the inlet collector to the outside, though it’s not going to look great, so we shall make a beautiful fiberglass air intake. 

Keep in mind that various makes/models of vehicles will have different designs for air intakes and air filter boxes. And make sure your workshop is ventilated well.

You will need the following materials/tools:
  • Fiberglass fabric;
  • Epoxy + hardener;
  • Construction foam;
  • Cardboard sheets (ordinary pressed cardboard); 
  • Masking tape;
  • Sharp, long knife;
  • Sandpaper, grit sizes 80;150;180;220;250;320;400;500;
  • Special sandpaper bar;
  • Several small brushes;
  • The spray can with acryl filler; 
  • The spray can with car paint; 
  • Soft yellow putty; 
  • Finishing gray putty. 

Step 1: Take the masking tape and apply it to where the future air intake will be located on the car bumper. Leave a little more room so as not to damage the bumper during the remodeling.

Step 2: Cut the cardboard and glue it to the inside of the bumper using masking tape. Do not spare the cardboard and masking tape; you have to glue it all qualitatively, without a single gap.

Step 3: Fill the cardboard and masking tape structure with construction foam. The foam will be the basis for the intake.

Step 4: Use the cardboard to trample down the fresh foam and secure it with masking tape, thus giving the foam the desired shape.

Step 5: Let the foam completely harden. Tear off the cardboard, both from the front and from the inside.

Step 6: If the foam is not enough, add some more and secure it with cardboard so that the foam does not spread.

Step 7: When the foam hardens, cut off the excesses with a knife. After that, shape the foam with a sandpaper bar (grit size 80).

Step 8: Mark the air inlet with a marker or a knife. Then cut off the excess foam and make a hole for the future intake tube.

Step 9: As you can see, the holes in the foam are large enough and not in the most suitable place. Therefore, cut the plug out of the cardboard and secure it with ordinary pins.

Step 10: The shape is ready, that’s what the future air intake will look like. 

Step 11: Now, it’s fiberglass and epoxy resin time. Some kits include fiberglass fabric and epoxy resin with a hardener/curing agent, which is very convenient.

Step 12: Unfold the fabric – it should be enough for the whole surface of the air intake.

Step 13: Mix the epoxy resin with a hardener and moisten the foam/cardboard mold with the solution.

Step 14: Apply fiberglass to the fully impregnated foam/cardboard mold, roll it with a brush, then apply another layer of the epoxy resin to the fabric.

Step 15: Impregnate every inch with epoxy resin. Do not put many layers of the fabric at once – a lot of epoxy resin can damage the look of the future part, deforming the shape when dry. Epoxy resin usually cures within a day, sometimes it takes two days, depending on the amount of hardener. When the first layer of the fabric and epoxy resin hardens, another layer must be placed to increase the strength.

Step 16: When the two layers of the fabric have completely dehydrated, the resulting semi-finished product can be separated from the main part (bumper), that’s when you need the masking tape that acts as a separator. First, cut off the extra foam on the inside of the bumper, then use a knife to cut the air intake from the bumper carefully.

Step 17: Use the sandpaper bar to treat the removed intake and cut off the excesses with scissors.

Step 18: After sanding the piece, use soft yellow putty. After it has dried, treat the section with the same sandpaper bar, changing the grain size in the following order 80/150/220/250.

Step 19: Putty the entire surface of the air intake using finishing putty and make it smooth with sandpaper grit size 150/220/250/320/400.

Step 20: Prime the surface with a white ground coat.

Step 21: After the coat has hardened, remove any irregularities using the finishing putty.

Step 22: Use the same sandpaper again. Repeat the priming, sandpaper with 400 and 500 grits, paint the intake.

That’s it.

Where can I get a cold air intake installed?

You can do that yourself (the installation process is quite simple, provided you follow the installation instructions and have necessary auto skills). But you can, of course, do that in any local authorized dealer/body auto parts shop. It will cost you around $150-$500, depending on your CAI system. 

However, make sure the CAI installation will not void your vehicle’s warranty, especially if you’re in California because they have their own regulations. So you will have to make sure your chosen intake system is CARB (California Air Resource Board)-certified. Pay attention to the kit characteristics, engine bay location (depends on your engine bay layout), and, of course, the expert level of your chosen team of mechanics.

Typically, a CAI doesn’t add enough power to make other parts fail, plus, the manufacturer will have to prove that your CAI has caused the malfunction/failure of the warranty-covered parts. All the rights are protected under the Consumer Products Warranty Act of 1975. 

How much does a cold air intake cost?

It depends on the package/part you would like to buy. Accessory prices start from $50 and go up to $2.500, while kits range from $200 to $1,200 on average, depending on the parts included.

Can a cold air intake damage your engine?

No, if it’s a high-quality intake (avoid cheap no-name intake systems). But for the best performance, you will still have to re-tune your engine to use the CAI. Unless the filter is clogged or you live where the rainfalls are heavy, and the intake can suck in some water, which may lead to engine damage, it’s all fine, and you will see no Check Engine lights. BTW, some companies offer a bypass valve for their CAI systems to prevent the ingestion of water. 

Is a cold-air intake a worthy investment for a vehicle?

Well, you know the possible benefits plus, it’s relatively cheap (one of the most affordable performance upgrades for a vehicle, in fact), and you can always do that just for the looks and sound. All in all, many will agree a CAI is a valuable enhancement to your car able to provide a noticeable difference in performance and improve your driving experience.

Will a cold air intake make a noticeable difference in power or fuel efficiency?

A slight positive difference is what you can expect. However, it may all depend on your CAI quality, engine, and vehicle characteristics/modifications. 

Does cold air intake make a difference in carburetor-fed engines?

Yes, the benefits are pretty much the same, but not everyone will really notice them. As you know, carburetors do not adapt automatically to ambient air temperature differences and, thus, need constant tuning. In fact, you may have to put your car to a dyno test to see the power difference. However, an expert driver should notice the changes.

About the author

Jim Malkovich

If you have any ideas or seek cooperation in any way, contact me today and let’s see where this leads us to. You can reach me at info@mechanicfaq.com

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