Do Charcoal Air Filters Rob Your Engine Of Horsepower?

hello everyone and welcome in this video sponsored by RetailMeNot we are continuing along with the theme of testing air filters so in a previous video we tested the original equipment air filter in my Subaru Crosstrek and then we also tested it against performance air filters and so in this video we're going to be determining whether or not charcoal air filters which is an additional filter within the intake system actually make a difference for performance and so the way that we're going to be testing that same as the previous video we're gonna be testing on a dyno measuring horsepower in torque and then we will also be using a knee box to test real-world acceleration with and without using this charcoal air filter so we're going to test it using the original equipment filter and we're going to test it with and without this charcoal filter using a performance air filter okay so the first and most obvious question is what is a charcoal filter and what is it for and so this is sitting within your intake so your air is going to come in from the front of the vehicle it is then going to pass through your air filter and then after passing through that air filter behind it is this charcoal air filter and the reason this exists is actually to prevent hydrocarbons from escaping from your intake and going back out into atmospheric air so why would that happen well think about when you shut your car off so you can have your positive crankcase ventilation system vent some of those fumes from the crankcase into your intake tract you could also have those fuel injectors which are port fuel injectors spraying fuel before the intake valves you shut the car off there's still some fuel sitting there in the intake tract so that fuel could work its way back up the intake and a vent to atmospheric air and so this charcoal air filter is what captures that fuel and prevents it from escaping into the atmosphere now as you may have figured out that means this charcoal air filter is a piece of emissions equipment and it is not intended to be removed in fact removing it is a permanent process it's not a reversible process in taking it out you have to actually cut some tabs and so what this means is you know you would not be emissions compliant if you were to take this off so for a road car for a street legal core you would not want to do this of course it would vary depending on which state you live in but typically the case is do not tamper with emissions equipment for all the Subaru cross prick track owners out there that are tracking their Subaru Crosstrek I'm sure it's a huge crowd this is going to provide plenty of insight into what happens when you do actually take this thing out which again you should not do unless you are specifically tracking your car not using it on the road now as mentioned this is a continuation of the previous video on air filters and once again is sponsored by RetailMeNot now if you're using websites like Advance Auto Parts or Amazon whatever it may be for buying car parts you'll likely notice that there are all kinds of coupon codes floating around out there to save money the free browser extension RetailMeNot is designed to compile all of those codes and make sure you're getting the best deal on the product when you checkout so it can be really helpful in saving some money I have a few videos coming up which I'll be using the tool for and I'm excited about the ongoing partnership every little bit helps you can find a link for the tool in the video description if you're interested and it works with all of the major browsers out there all right let's jump right into the dyno testing so each option had three dyno runs and then we're going to be comparing the top horsepower and torque figures from the best dyno run for each so with and without the charcoal filter and then for both the stock and a performance air filter so 12 total dyno runs here and so our first option stock filter with the charcoal air filter installed 160 horsepower 137 pound-feet of torque then we removed the charcoal air filter just running with the stock air filter 164 horse power almost 142 pounds of torque so an increase of 4.1 horsepower by removing this charcoal air filter as well as 4.4 pound-feet of torque by removing the filter so 2.5% more horsepower over 3% more torque and all we did was remove this charcoal air filter next we ran the test with the performance air filter and the charcoal filter as well so both filters we're looking at 164 horsepower 142 pound-feet of torque then we remove the charcoal air filter leave the performance air filter and we are looking at 167 horsepower 143 pound-feet of torque an increase of 2.7 horsepower and about half a pound foot of torque and that means one point percent increase in horsepower and about 0.36 percent increase in torque without running the charcoal air filter and using a performance air filter alright so now we want to see if we can verify the results that we saw on the dyno out in the real world and so we're going to be using the B box in order to do this the testing is going to be conducted exactly the same as it was in the previous video and testing stock filter versus a performance air filter so we're going to be using both of these filters with and without the charcoal filter and we're going to be measuring from 20 miles per hour to 60 miles per hour on the same strip of road doing three passes all in second gear never leaves second gear flat foot flat on the accelerator and we're going to measure that acceleration from 20 to 60 miles per hour as well as from 45 miles per hour to 60 miles per hour so that 45 to 60 will be the top range of the engine and the higher rpm the 20 to 60 kind of gives us an overall was there an overall improvement the 45 to 65 looking at a narrower rpm region of the engine all right first up 20 to 60 miles per hour with the stock filter with the charcoal filter we're looking at nine point zero one seconds very impressive you can see why people are gonna want to take one of these bad boys on the track 9 seconds from 20 to 60 miles per hour from 45 to 60 miles per hour three point six one seconds with the stock filter and the charcoal filter when we remove this charcoal filter and just use the stock filter we're looking at eight point seven three seconds in order to get from 20 to 60 miles per hour and three point four six seconds in order to get from 45 to 60 miles per hour so a consistent improvement versus what we saw on the dyno three point one six percent improvement twenty to sixty mile per hour and a four percent improvement from 45 to 60 miles per hour so consistent results that we verify with the dyno three runs out in the real world three runs on the dyno and it looks like the results actually do match up for the stock filter with and without the charcoal filter next of course testing the performance filter with the charcoal filter twenty to sixty time of eight point eight one seconds 45 to 60 miles per hour in three point four nine seconds then taking the charcoal filter 20 to 60 miles per hour in 8.7 seconds 45 to 60 miles per hour in 3.46 seconds so once again this was actually pretty close to the results we saw on the dyno so about a 1.6 percent improvement on the dyno 1.25 percent improvement 22 60 miles per hour here with the performance air filter and no charcoal filter now another really interesting observation between these two filters is that once you take this charcoal air filter out the stock verses the performance filter really makes no difference we saw in the exact same real-world times so eight point seven three seconds with the stock filter twenty two sixty eight point seven seconds with their performance filter twenty two sixty and both of them had the exact same three point four six seconds to go from forty five miles per hour to 60 miles per hour so removing this these are basically equalized and they give you the exact same real-world performance results now so far all of this may sound very exciting and you may be thinking wow this is a great idea I'm going to remove my charcoal air filter and so in order to bring down that enthusiasm we're gonna do a little math and it's not math itself that's the reason why you're gonna get bummed out math is exciting it's what this math shows us that is the reason you're going to be bummed out so we know that average acceleration is equal to the change in velocity over the change in time in this case we're accelerating from 20 miles per hour to 60 miles per hour using a stock filter with and without this charcoal air filter and it was able to do so in nine seconds with this charcoal air filter and eight point seven three seconds without so our change in velocity is 40 miles per hour 60 minus 20 or 50 eight point six six feet per second we're going to divide that by time in the case with this charcoal air filter that's nine point zero one seconds and that gives us an acceleration and average acceleration from 20 to 60 miles per hour of 6.51 feet per second squared if you divide that by 32 point two that gives you acceleration in G's point two zero two g's that's the acceleration that this bad boy is capable of now if we do the same math with the charcoal air filter removed then we get 6.72 ft/s^2 for acceleration divide that by 32.2 it gives us point two zero nine GS in other words the difference between removing this air filter and having it within the air intake system is point zero zero six five g's less than 1/100 of a G in acceleration you will not feel that so people that said I took my charcoal air filter out and suddenly I have all this power and it feels like it accelerates a lot faster unfortunately it is just not backed up by math point less than 1/100 of a G and acceleration you are not going to perceive unless you have some crazy sort of ability in order to perceive g-forces so unfortunately real world you're not going to be very excited simply by removing this now another thing you might hear people claim in some forums perhaps saying they got rid of their charcoal filter is that they you know they didn't see an improvement in power or acceleration but they saw an improvement in throttle response and here's why that's a pretty silly thing to say because throttle response really isn't going to be dependent on this tiny little restriction within your intake system so what's going on with your engine and modern engines keep in mind are all using electronic throttle so there's an electric motor that's dictating how open is this throttle valve so on one side of your throttle valve you're gonna have atmospheric air there's not really much of a restriction between this side of the throttle valve and atmospheric air so that's what the pressure is gonna be on one side on the other side closer to the engine because this throttle valve is closed you're going to be pulling a vacuum from the engine that engine piston is moving down it's trying to pull an air but this is acting as a restriction so throttle response is that time duration when you ask for an input your input being pressing on that accelerator pedal and getting the response from this throttle valve and so once this throttle valve opens it allows that atmospheric air that's on one end of the throttle valve to travel to your engine and that delay is that delay and in response that you will feel in your engine when you press on the throttle and you don't have it immediately it takes a little bit of time for that air to travel from this side of the throttle valve to your engine now with elect control throttle valves this is purely going to be a function of how that throttle is mapped based on how the manufacturer said it so they decide the parameter of how much throttle input equals how much open is this throttle valve and that's where you're going to get your throttle response from and you're going to have very close to atmospheric air yes you have a few restrictions in the way but it's going to play a very minimal role in affecting what is the pressure on this side of the valve and as a result it's going to play a very minimal role and what your actual throttle response is so removing this isn't really going to change your throttle response having a differently tuned electric motor that opens your valve that's actually what would change a significant amount of your throttle response so for example in the Subaru STi you've got an intelligent mode a sport sharp mode you'll notice a significant difference in throughout a response between those two modes depending on how much you press in the gas pedal what you get in return is different because the electric motor is tuned differently it's mapped differently for those two different modes alright so finally what is my recommendation and what am I going to do with my own course so for me personally looking at this I thought it was very cool that we actually did see a measurable difference with and without the filter consistent results on the dyno and out in the real world I think that is super cool unfortunately not something that you can actually feel and so because you can't feel the difference and it's no longer missions compliant if you take this piece out for me it's a very easy decision I am leaving it in no problem whatsoever the Subaru Crosstrek is a slow vehicle I cannot change that it will remain slow but interesting nonetheless learning with and without what the difference is 2 horsepower torque and how this thing accelerates huge thank you to RetailMeNot for sponsoring the video again that link is in the video description thank you all so much for watching and if you have any questions or comments of course feel free to leave those below

Channel: Engineering Explained

Views: 306,434

Rating: 4.919692 out of 5

Keywords: air filter, performance air filter, horsepower, torque, engineering, science, dyno, charcoal filter, does it work, test, garage, explained, how it works, car filter, diy, car repair, automotive, auto tech, auto diy, chrisfix, doug demuro, donut media, engineering explained, how cars work, dynamometer, dyno testing

Id: F1JmOKKAgyQ

Length: 12min 59sec (779 seconds)

Published: Sun Feb 17 2019

Reddit Comments

[u/The-john-2]

They arent liars per se, it may be a sort of placebo affect, in which they think they'll feel the difference, thus, they 'feel'a difference, despite whether there is one or not

[u/JayRollaNuggFan]

The placebo affect is real. The goal is to combine bolt ons to get real gains. An engine is pretty much just an air pump. The more easily it breaths and exhales the more power it can make. A single bolt on to say an LS motor wont be noticeable. But combine a high flow intake, TB, intake manifold, header, xpipe and exhaust they will net you a good 40+whp. More when tuned.

[u/heylookitscaps]

On turbo cars it does sound better tho 🤷🏻‍♂️

[u/[deleted]]

I remember swapping my stock air filter out for a K&N, it made my feel like the turbo was spooling sooner... but Mabye it was in my head? 🤔

[u/ghdana]

This video is about removing charcoal filters, not all 5hp mods. Changing filter types can increase air intake, specifically if you feed it right into the engine. Of course it also sounds much better with a more aggressive filter or open top box.

Like the 2019 WRX STI has 5 more hp than the 2015-2018 and you can honestly feel it is different.

[u/notkeegz]

I think people ITT don't understand what the placebo effect is....

It's not when you do something that should have no effect and you think it does, when it actually doesn't. It's when something has the desired result after doing something that shouldn't have had any effect to begin with.

Like if you're in a high blood pressure study and are placed in the placebo group. You should still have your high blood pressure since you aren't getting actual medication, but somehow because you think you're taking the meds, you still get the desired effect of lower blood pressure. With these air filters (or the removal of them), people are just being fucking idiots and think there car is quicker/faster when it's exactly the same but louder. That's not a placebo effect. The actual placebo effect would be you thinking that removing the air filter, which should have 0 effect on actual performance, ends up somehow granting your car performance abilities it shouldn't have.

[u/ej255wrxx]

OP's title doesn't really match what the video is saying. Does the mod add 5 HP to the peak power or does it add 5 hp across the entire RPM range? Does it perhaps add more than 5 HP at lower RPM but only 5 at the top end? I have no doubt replacing an filter doesn't make a noticeable difference like the video states but to then extrapolate that for every single performance mod that adds 5 peak HP doesn't seem accurate to me. With full bolt ons I only gained about 6 HP at peak but I gained between 18 and 25 for the 4500 - 6300 RPM range. Tell me I can't feel that difference before VTEC kicks in (yo)...

[u/cadomski]

My car feels faster after I wash it. That should tell you all you need to know.

[u/Gregdrivn]

It depends on the vehicle, driver, familiarity, weather, and more.

The higher the power to weight ratio the harder to tell. Turbocharged even harder. Throttle by wire with adaptive throttle ramping curves, even harder, borderline impossible, but still possible.

Hearing a difference makes you feel it immediately. Breaking traction for the first time makes you feel it immediately. An old car that really needs some love (plugged air filter, new plugs, cleaned maf, carbon buildup, tires, etc) and gets it and you will feel it immediately. Changing the helmholtz resonance characteristics of the induction system and you will feel it immediately, if you are the type to pay attention to it. Get a lighter clutch, or lighter rims, and your hp will not go up, but you will definatly feel it immediately.

I notice if I have a pebble stuck in my tire tread. My heighbor didn't notice a missing wheel.

One night I noticed an inexplicable performance boost mid drive, it was so good I took the side roads and enjoyed an extra hour trying to convince myself it was all in my head and it was just the good weather. But I was right, I wasn't crazy, as I slowly took the turn into the driveway it became abundantly clear my powersteering was gone, the belt fell off. I couldn't be saving more than 3 hp without the pump running, even less in a straight line, but the difference was noticeable enough to me, so much so, that I later ended up removing the replacement belt after installing it...

To be fair this is all on an NA Miata...

P. S. I get not being able to feel a minute improvement, but how to people not notice missing wheels? I get maybe not feeling a flat if your car is balanced, you are on medication, and you drive 5mph, but seriously... a missing wheel?