How Much Horsepower Does A Cold Air Intake Add?

A cold air intake is popular among car modifiers and boy racers. They’re the ultimate image of Fast and Furious-esque velocity and power.

And, let’s be honest, they do look great! You’ll get them in a variety of colors (including plain black). The vibrant reds, greens, and blues make an engine stand out against the crowd.

But how feasible are they? Does a cold air intake really add horsepower, or is it just for display?

In this guide, I will clarify what cold air intakes are and how they operate.

You will then see why adding a cold air intake (without modifying anything else) has minimal impact on horsepower.

What Is A Cold Air Intake?

A cold air intake is a specially designed automotive air intake. They’re designed to pull colder air into the engine than the standard part.

All cars come with a standard air intake. It’s how the engine breathes, drawing in oxygen to burn the gas or diesel.

In most cars, an air intake is little more than a plastic tube with a filter (air filter). This then feeds into the intake manifold, where it’s divided up (avoiding technical terms) into different cylinders.

**A cold air intake replaces the plastic intake tubing and filter**. In the vast majority of cases, the intake manifold remains as stock.

Cold air intakes also usually come with a washable air filter, distinctly cone-shaped. These allow more air past than the regular disposable paper filters in the air box. You also don’t have to throw them away!

At the same time, you’ll notice that the engine noise changes. It’ll sound throatier and more hostile. Of course, the precise notes depend on the design and your motor.

Before you install a cold air intake, you should check if it’s legal. Rules vary from state to state. Unfortunately, they’re now prohibited in most parts of the country.

You could still install one on a non-road car, such as a competitive track car.

What Does A Cold Air Intake Do?

A cold air intake aims to bring cool air into the engine.

Each part is designed individually for a specific car. The intake draws oxygen from a location that’s naturally cooler than elsewhere.

It then uses a distinctive airflow design to maximize the rate of oxygen going into the cylinders. This (theoretically) increases the engine’s horsepower output.

Some high-performance cars come with cold air intakes as standard. However, almost all you’ll see are bolt-on aftermarket parts. They’re typically quite easy to install, although you should get a mechanic to help if you’re unsure.

Does A Cold Air Intake Increase Horsepower?

**The straightforward answer is yes – in theory**. **But if all you do is switch out the regular intake for a cold air model, it’ll have minimal impact.**

Cool air intakes improve the rate at which oxygen gets into the combustion chambers. More oxygen means more potent combustion when the spark plug fires.

This drives the piston down, cranking the crankshaft with more force. The flywheel and transmission then send this power to the wheels.

How much they enhance this rate varies from model to model and car to car. On some vehicles, cold air intakes will have minimal-to-no impact whatsoever.

If you read the product descriptions and mission statements on aftermarket cold air intake company websites, you might be led to believe that these are exceptional products that substantially boost your power output.

While it’s true that they can, you aren’t going to be flying into hyperspace anytime soon. Most offer nearly negligible benefits.

That said, a cold air intake can be used alongside other modifications to produce a substantial overall hp increase.

Why Does A Cold Air Intake Increase HP?

As mentioned, you won’t actually see much (if any) increase in hp from a cold air intake. But you will most likely find one or two additional horses (no matter how minor of a difference that makes).

Here’s where they originate.

The science behind cold air intakes is quite basic. Cold things are denser than warm ones.

As a straightforward example, consider water. It’s evident that ice (cold), a solid substance, is denser than steam (hot), a gaseous matter.

(If you’re interested in the science bit, scroll down a few sections to learn more.)

Air contains about 21% oxygen at all times. Because cold air is more dense, there is more of it in a given space. This, therefore, means there is also additional O2.

As you’ll recall from school, fire requires three things. The Fire Triangle consists of heat, fuel, and – anticipate it – oxygen. In automobiles, the heat (ignition) comes from the spark, while the fuel is petrol or diesel.

More oxygen means fuel combusts with greater intensity. For instance, using bellows on a wood fire increases flame height and heat output. In reality, you’re increasing the oxygen flow – the same principle as a cool air intake.

How Much Horsepower Does A Cold Air Intake Add?

Again, a straightforward figure can’t answer such a broad question. It’s simply untrue to say that cold air intakes always add 10 hp or 5% of your engine’s power.

It’s entirely dependent on the following factors (and more):

• The design of the cold air intake
• The car’s engine design
• How cool is the air coming through the cold air intake
• The quality and cleanliness of the filter
• How well was it installed
• Etc.

Most companies will claim around a 5% boost in horsepower. Again, this depends entirely on your vehicle and cool air intake model.

Nevertheless, 3% to 5% is probably a sensible figure. If, by some miracle, you find that you gain even more hp, it’s a extra benefit.

To put some figures to that, your 200-hp motor might kick out 210-hp with a frosty air intake. That’s a 10-horsepower gain – not too noteworthy, right?

(Of course, you could equally argue that 10 horsepower is still 10 additional horsepower. How valuable is that to you?)

As you might expect, cold air intakes have a more significant effect on larger, more powerful engines. The bigger the motor is in the first place, the more horsepower a cold air intake will add.

As such, they’re worth considering for high-performance cars such as a Ford Mustang or a Dodge Charger. However, to be realistic, putting one on your aging Honda Civic daily driver is barely worth the trouble.

Modifications To Add Horsepower Alongside A Cold Air Intake

The most advantageous way to add a cool air intake is to do other modifications alongside it.

Before you start modifying your vehicle, remember:

• Car modifications might void your warranty (if applicable).
• You should declare all modifications to your car insurance.
• Most car mods don’t do much for your performance. The vehicle is still limited by road laws, manufacturer restrictions, and limitations of the laws of physics.

If you do decide to modify your car, remember to upgrade the tires and brakes, in particular. If you find extra power from somewhere, your vehicle must be able to handle it.

Failing to do this is likely to result in a severe crash.

Here are a couple of recommendations.

Engine Rebuild

This is always glanced over and ignored by many wannabe mechanics. But it’s actually the most efficient way to “gain” engine power.

Through the lifespan of an engine, it gradually loses power. This comes from carbon buildup, rust, debris, and compression loss.

In fact, once a car reaches 100,000 miles, it will probably have lost 10% to 30% of its original power output.

An engine rebuild involves stripping your motor down to its basic components. These can then be cleaned or replaced as needed. New seals and gaskets repressurize everything.

After this, it’s reconstructed and dropped back into your car.

You could add a cool air intake at this point.

The rebuild is really just routine maintenance. You don’t need to declare anything about the rebuild on any legal forms since it’s still exactly the same. (You might need to mention the new air intake.)

However, you’ll almost certainly notice a massive horsepower increase – more than anything else can give you (percentage-wise).

Engine Remap

After an engine rebuild, a remap is the next best thing to increase your car’s horsepower. Do it alongside a cool air intake to boost the effectiveness.

This can entirely alter your car’s power output. You could make it focus on more power or greater fuel efficiency if you prefer.

Take your car to an experienced remap technician. They can adjust the software in your ECU to maximize the usage of enhanced airflow.

You could choose to have them install a pre-configured chip, too. They’ll run you through your best options.

A vital thing to remember: don’t overdo it. It’s tempting to go for Stage 2 or 3 chips (with their corresponding mods). You’ll achieve nothing more than blowing your engine up if you aren’t careful.

Be practical. If a remap or chip can offer you a 10% horsepower gain on top of the frigid air intake, take it.

Once again, you’ll have to declare this alteration on your coverage.

Performance Exhaust

It’s one thing to get more oxygen into the engine, but it’s almost worthless if you can’t get the waste gases out. These essentially choke the incoming air, diminishing its effectiveness.

By replacing your stock exhaust with a high-performance model, the total engine airflow – from the intake to the exhaust tip – improves.

Again, a performance exhaust is unlikely to have any substantial impact on your horsepower. However, it and the cold air intake will complement each other, with a greatly improved flow from start to finish.

If you can, it’s worth buying a cold air intake and sturdy exhaust from the same company. This way, you have the best chance of performance increases.

Legally, you may have to declare your powerful exhaust on your insurance.

Even if you don’t see any hp gain with the cold air intake and performance exhaust, your car will sound fantastic. If anything, be careful it isn’t too loud – you don’t want to receive a noise complaint or get pulled over by the police.

Forced Induction (Supercharger Or Turbocharger)

Before installing a forced induction system, you should carefully plan it out. Forcing too much pressurized air into your motor could overwhelm it and blow all the seals and piston rings.

It must be correctly installed by a reliable mechanic. There are many complex things to consider, such as new oil lines and quantities.

Superchargers and turbochargers both draw additional air in. Superchargers are belt-driven, while a turbocharger turbine is powered by exhaust gases.

You’ll see significant horsepower gains with forced induction. Pairing it with a cold air intake will provide even more oxygen (but hardly any in comparison).

Make sure you reinforce the engine and drivetrain before running a forced-induction system.

Again, you’ll need to confirm all the legal aspects first, too.

Why Is Cold Air More Dense? (The Sciencey Bit)

If you’re enthusiastic, here’s the technical portion.

What Is Density?

Density is (in physics terms) “the quantity of mass per unit volume.”

For example, a box filled with bricks weighs more (or, technically, “has a larger mass”) than the identical box filled with feathers.

This is because the bricks are more dense; they have more mass occupying that space.

The Physics Of Hot And Cold

Temperature is simply a measure of kinetic energy.

The more energy particles in a substance have, the more they fly around, colliding into each other and occupying as much space as possible.

A hotter substance contains greater kinetic energy compared to a cooler substance. The colder an object is, the less active its particles become.

Convection

Convection is related to density and temperature. It’s the principle that hot air (or any substance) rises, while chilly air sinks. It’s nearly always warmer upstairs than downstairs, for example.

Let’s revisit density quickly.

Density can also be explained by thinking about whether something floats. If it does (for example, a cork or an entire vessel), it’s less dense than water. If it sinks (like the previously mentioned cubes), it’s more dense.

What Does This Mean For Cold Air Intakes And Horsepower?

Take these concepts and apply them to the environment.

Warm air is less dense because its particles have more energetic. They’re zipping about all over the entire region.

Cool air is denser because its particles aren’t as vigorous. They’re occupying a smaller volumetric space than the warm air.

Your engine will still suck in the same volume of air (using pressure differences). However, cold air weighs more than the equivalent capacity of hot air – there is literally more of it in freezing conditions.

In turn, this means more oxygen. And that, as explained above, means improved power from the ignition and, thus, additional horsepower.

Cold Air Intake Positioning And Density

One final note on density and cold air intake positioning.

You’ll usually notice that cold air intakes point or even bend downwards. This is typically different from the stock intake, which generally extends out horizontally behind the grille.

Why does the cold air intake point down? Well, refer to the above.

Denser things sink. Cold substances are more dense. Chilly air falls while heated air rises.

This is where the cold air intake finds its cooler air: simply by pointing downward.

Is A Cold Air Intake Worth Getting For More Horsepower?

So, you want more horsepower? There are better alternatives than a cold air intake.

In the end, a cold air intake for a road car will do very little other than change the engine noise. You’ll see tiny horsepower increases. They’re more for show than anything in most cases.

That said, you could use it as part of a series of modifications. Expect modest horsepower gains from these individually, but you might get more substantial results when they’re combined.

Then again, if you just want your car to look as amazing as possible, a cold air intake is an excellent place to start.

If you’re thinking of installing one, K&N is the most reliable brand on the market. They’re outstanding value, too.

Get it installed by an automotive mechanic if you’re unsure what you’re doing! And remember to check the legal requirements!

Stay safe!