How Much Horsepower Does a Cold Air Intake Add?

A cold air intake system (CAI)  is often the first performance upgrade in engine tuning done by many car owners. It's easy to install and also efficiently reduces hot air amounts entering the engine, thus increasing the efficiency of filling the cylinders with it and adding some noticeable HP gains.


When looking for cold air intakes, everyone wants to find the best fit for their vehicle as well as make sure that the system will do exactly what it's designed for. Today we're going to let you know how much HP should you expect from a high-quality aluminum cold air intake.


The short answer to this will be from 5 to 15 HP, though it all depends on the intake type, its location, car make, model, and your engine size. 


To provide effective performance, cold air intakes need denser and colder air, thus, they are often installed closer to the fender instead of the stock location. Some air intakes also use large air ducts located in the front-most part of the engine bay to feed large amounts of cold air to the engine and avoid heated air. 


The materials used in the air intake filters are mostly oiled/dry cotton or paper. Oiled cotton filters increase filtration but reduce the airflow to the engine, dry paper filters are vice versa.

The System of Cold Air Intake


Now, a Cold Air Intake (CAI) is a system that supplies cold air to the engine intake manifold.

The system consists of:

  • Intake filter
  • Air duct

A CAI system is used on both naturally aspirated engines and turbo engines.


A standard intake system typically has high airflow resistance. This is due to a paper filter and the manufacturer's desire to reduce noise. In addition, stock air intakes usually suck hot air from the engine compartment. The air is hot both because of the underhood space temperature and heated plastic tubing located directly next to the engine. All this reduces HP.

But we can fix this with a cold air intake system!

CAI system advantages are as follows:

  • Increased HP and torque by allowing more air to enter the engine;
  • Cooler and denser air (compared to hot air in the engine compartment);
  • Increased accelerator pedal sensitivity;
  • Reduced fuel consumption;
  • Reduced detonation risk;
  • Smooth and soft engine run;
  • Quick turbo-compressor start.

Cold air intake filters can have carbon or aluminum cones, which are pressed tightly onto the filter component and shield hot air coming from the engine. 


A few months ago, we at MechanicFAQ, tested a few Honda intakes and figured that a standard rubber intake tubing raises the air temperature by 2-3F, compared to aluminum CAI systems. The internal shape of the stock tubing is far from perfect and has many irregularities that impede airflow efficiency. Due to this, the air temperature increases. Also, tube cross-sections are not optimal, which creates airflow issues and increases the air temperature.


Of course, CAI design provides not zero but very low airflow resistance. During operation, both the shape of the cone, chosen for the filter, and filter component configuration itself create auxiliary vortexes that contribute to the more efficient filling of the cylinders.


Every driver knows the power of the oncoming air pressure - just stick your hand out the window as you drive. Harnessing this dynamic pressure allows for a denser, packed charge.  The colder and denser the airflow, the better the fuel that it interacts with burns. It is this force that is used by a cold intake system to increase engine power and lower fuel consumption.

Basic cold intake system design principles:

  • The air is taken from the coldest places;
  • Most optimal filter location;
  • Smooth tubing;
  • Shortest possible filter-manifold path;
  • Heat-resistant materials.

For turbo motors, the intake air temperature is just as important, because the lower it is, the lower the compressed air temperature, and the easier it is for the intercooler to reduce charge temperature, improve power and minimize dangerous detonation. Also, reduced resistance at the intake makes the spool earlier and more efficient.

Even the shape of the inlet connection pipe plays a big role. Our experience shows that a turbo engine with the correct intake can boost 500-1000 RPM earlier than without it.


An important issue for both naturally aspirated and turbo engines is intake airflow filtration. To reduce resistance at the inlet, it is common to install an intake filter. But reality shows that a standard CAI filter, even a good one, often cannot cope with dirt and dust which we breathe in. Regular intakes let too much dust into the engine, and this is often the cause of breakdowns. 


Aluminum heavy-duty filters are the only solution that allows the intake air to be filtered normally. They are designed for particularly harsh desert conditions and capture even the smallest particles of dust while reducing airflow resistance.


Installation of this equipment requires a highly qualified specialist and takes quite a lot of time, as you have to find and choose the right spot in the engine compartment, far from heat sources to completely eliminate hot air in the cylinders.


In addition, it should be emphasized that the installation of the system makes sense only when the entire engine has been modified. 

Conclusion

An average CAI system will add from 5 to 15 HP to your engine, depending on the type, location, car make, model, and engine size. Sometimes, you can reduce the flow resistance without worsening filtering quality. Not all CAI systems are able to do that but leading manufacturers often produce washable, space-efficient, eco-friendly, and affordable designs without sacrificing filtering quality.  


With that said, if you really want to really feel the difference, increase your engine's performance and efficiency, you will have to tune your engine and team up your CAI with other engine modifications, e.g. new exhaust. 


Other than that, a CAI system is just one step but, as mentioned earlier, a huge step and an efficient replacement part to begin with - a high-quality aluminum CAI will make your engine perform better!

Dale, a Burns Stainless Blog Contributor
Dale is an automotive fan, journalist, photographer, racer, Ring Taxi driver and he runs the largest unofficial Nürburgring fan site BridgeToGantry.com

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