There are many questions when it comes to car air filters:
- Does removing air filter increase horsepower?
- Does removing air filter make car sound louder?
- I accidentally drove some miles without an air filter – is it okay?
- My car runs better without an air filter – why?
In this article I will cover car air filters in detail and answer all the frequently asked questions. Whether you are casual drivers or car enthusiasts, stick around. You will learn some stuff.
For a quick summary, you should not drive without a car air filter. Dust, debris, insects and other air impurities will enter the car engine and cause problems – internal scratches at best and engine failure at worst.
Removing the air filter will increase 1-2 horsepower at best – insignificant and you will barely even notice it. So it’s best to leave it on. Look into performance air filters like K&N instead. I have an article here about it. What Does a Performance Air Filter Do?
Before we go to the details, let’s first understand the role of air filters in a car. You see – to generate power and move, a car needs to mix oxygen and fuel in the combustion chamber. To increase horsepower you need more of both.
Fuel comes from the fuel tank, whereas oxygen comes from the surrounding air (sucked by the car’s intake system). Depending on where you live, the surrounding air could be full of dust, debris and insects.
These impurities in the air must first be filtered before the air can reach inside the combustion chamber. This is where air filters come in – they are usually made of special paper or foam that traps impurities.
Can a Car Start Without an Air Filter?
A car can start just fine without an air filter installed – initial power is supplied by the car battery and air from the atmosphere can still be sucked in (even better air flow without air filter).
So if your car is not starting, it’s not because of a missing air filter. You might want to check the battery, spark plugs or timing belt. But that’s a topic for another article.
How Long Can I Drive Without an Air Filter?
You shouldn’t drive your car without an air filter. It will seem fine and even run better (more responsive) because of the increased air flow. However, the long term damages could be big.
If you must absolutely drive it for short distances, it should be okay. A few miles or so will not suck in so much dirt that will cause anything serious. I am assuming you are driving in the city with proper roads and not off-roading (if you are, better not risk it!).
If you happen to drive long distances without an air filter, then you risk lots of things. I will cover more of these in the section below when I discuss the cons of driving without an air filter.
Also, there are times when your mechanic takes off the air filter when stationary and hits the throttle. You don’t have to freak out on this – if the car is stationary and it’s not extremely dusty, it’s ok.
Fun fact – when you go for a regular service, your mechanics probably take off the air filter when cleaning your throttle body. So again, it’s nothing to worry about.
Can I Drive With A Damp Air Filter?
If you are using a reusable performance air filter that needs cleaning, this is a valid question. The answer is yes, you can drive with a damp air filter and it will not cause engine damage but it’s still not recommended because a damp air filter will be more restrictive – reducing your car performance.
The moisture takes up space in the air filter that could have otherwise been used by air to pass through. This means less air flows into the combustion chamber and less power is generated by your car.
What’s worse is, dust that sticks into the wet air filter can accumulate and form an impenetrable layer for incoming air. When this happens, you need to re-wash your air filters as soon as you can.
Other than this, you don’t really have to worry. The moisture in the air filter will not leak into the engine and cause problems. Unless your air filter is soaking wet and is dripping with water.
Does Removing Air Filter Increase Horsepower?
Removing the air filter will not increase horsepower. Even if it does, it will be insignificant – mostly 1-2 horsepower. This is because modifying the air filter alone will not make a big enough impact on your car’s air and exhaust flow to increase performance.
If you are serious about horsepower gains, you need to replace various parts in the car. Things like the intake system, exhaust pipes and downpipes (if you are running turbo). And don’t forget to bring your car for a tune afterwards.
Most enthusiasts perform these modifications gradually. They start with a cold air intake (or at least a cone air filter) and then work their way up to the exhaust system. So no, removing the air filter alone will not increase horsepower. Don’t do it.
Does Removing Air Filter Make Car Louder?
No, removing the air filter from a car will not make the car louder. Air filter is located inside an air box – which is designed by manufacturers to silence as much intake sound as possible. Removing just the air filter will not impact sound.
To increase the intake sound, you want to remove the air filter cover instead. I cover this topic in another article. Can You Leave Car Air Filter Cover Off? There are also many pros and cons to this. I suggest you give it a read if you want to do it.
Driving Without Air Filter: Pros & Cons
Now that the details are discussed, let’s summarize them as pros and cons.
- Increased air flow. The only upside from removing your car air filter is the increase in air flow. This is supposed to increase horsepower but as I said, removing the air filter alone will not make a big enough impact to increase horsepower. Expect only 1-2 horsepower improvement.
- Risk engine failure. Without an air filter, there’s no stopping debris, dust and insects from entering your car engine internals. This will cause internal scratches and tears to the piston walls. Prolonged occurrence can even cause engine failure when you have accumulated debris flowing around your engine.
- Risk turbo failure. Turbo is an aftermarket part that compresses air and feeds it directly into the combustion chamber for increased performance. Now that air particles contain debris and dust, it can cause turbo to fail while compressing air at high speed.
- Does not increase performance. The only reason why you might be tempted to remove your car air filter is for improved horsepower. How ironic is it that doing so won’t actually give you significant performance gain and instead risk failure?
Do not drive your car without the air filter in place. If you want to tweak your air filter for performance or sound, I suggest you look into cone air filters or cold air intake.
These aftermarket parts will replace your stock air filter and air box. They aim to increase air flow significantly by using a bigger air filter and have them exposed to the environment.
Most of the time these parts are marketed to improve performance. But their true beauty is their sound. You could hear the sound of air rushing into your engine as you accelerate. This is a very satisfying sound.
Listen to 3:59 to know exactly what I am talking about.