Do Cold Air Intakes Increase Horsepower? 

Not gonna lie, spaced out a bit while u were teaching. Will rewatch the video

I graduated with a BS in mechanical engineering. Most of my videos I've learned myself by reading and watching everything I can find on autos.

I ran a duct from my intake, out through the hood , wrapped it around to the inside of my open drivers window to just in front of my A/C outlet. I blast air conditioning freezing air into it and get 100 extra horsepower

Feel free to ask questions - I try to make my videos clear to any age group. That said, many things can be confusing if not watched in a particular order, or without pre-existing knowledge. I try to make videos which explain all of the details that work as a system, rather than individual videos that repeat information. Let me know what questions you have, and I'll try my best to help.

Best free teacher ever. Need to make myself a plaque!

I tried to keep it pretty simple, it's always good to learn new things my friend!

I have learned more from watching 10 mins worth of your videos than I learn in a whole 7 hour school day

You're very welcome, thanks for watching!

Basically, pick whichever you would like. Based on what I discussed in the video: 10 degrees cooler = 3.3% more power; 10 degrees warmer = 3.3% less power.

Rain water shouldn't be too much of a problem, but if you were to ever run over a puddle or get into decently deep water, you could risk hydrolocking your engine - filling the cylinder with water and then braking the weakest link, usually the connecting rod.

Most of the restriction is the paper filter element and tiny stock snorkel intake opening. For manufacturers paper elements are cheaper, and the small inlet opening to the air box is in the interest of quietness. So if you use a wide-open high flow filter located in a separate cool part of the engine bay you can get a 5-10% power increase and a racy intake howl when the revs get up. Cooler air is denser and contains more oxygen.

Haha me too! Glad you enjoy the videos and learn from them!

It might suck up a curious kitten and you'll get a cat-back exhaust.

Yes, they have an excellent video on the subject, hence I tried to take a different approach.

It's good to see you still posting videos. I have learned a lot thanks man.

Yes, the volume remains the same. All I'm saying is that 4 liters of air at 300K has the same amount of oxygen as 4.13 liters of air at 310K (with the given assumptions). Thus, 10 degrees equates to 3.3% more air.

As mentioned before, the automotive engineerings who design the air intake system do a good job at designing the intake system to meet their goals. However squeezing hp out of the engine is rarely their goal. In most modern application emmison rules drive a large majority of the design. Another large concern is sound level. Even performance cars have fairly low intake noise. Therefore, cold air intakes increase horsepower by changing the design to focus solely on performance. Some of these gains are from decrease charge temp and others are from improved flow characteristics.

you are well spoken and clear, I just stumbled on your site. nice work! It is a shame that most kids that put these on their engines have them installed to pull in under hood temp air. Completely defeating the purpose of it.

for Honda guys, instead of putting the metal tube for a cai, or short ram, just get a factory type r intake tube. it has smooth walls and radius. don't let the outside fool you, it flows very good, then just put your cone filter on it, and get fresh air from outside of the engine bay, then get rid of the lower portion of the air box because it's very restrictive, and you lose a bit of unneeded weight too. for added smoothing of the air, get a velocity stack, they aren't heavy, and it helps smooth out the air

Glad to hear it, thank you!

Great video however, keep in mind I have to take off my boots just to count to 20.

Your videos are GREAT! You have all your information prepared so you don't "uuumm" and pause at all, keeps it interesting. Good work, thanks for the videos!

What parameter would you change in order to make the most of a CAI? Shouldn't the ECU know when there is more oxygen present?

Finally. Someone that deserves the amount of subs he has. Great video brother. 10/10 explanation.

Thanks for subscribing, cheers!

Awesome, thanks for sharing!

It's basically the volume of the engine (the amount of space displaced by the pistons). Check out my video on engines. Obviously larger engines have the potential for more power, but you want to size the engine based on what you want the vehicle to achieve (high power vs good fuel economy, etc.).

Awesome video man! love the theoretical explanation!

I just visited your website. You have good lessons on there! I'm an IT guy so I mostly tinker with electronics of that nature but I really enjoy learning all you share about cars almost as much as I enjoy learning about IT.

Same amount of air by volume taken in, more air by mass since it's more dense. You are correct.

This is the best channel I've ever subscribed to. Keep doing what you're doing!

Lies! I checked your channel, you've been subscribed for a month. Cheers

Theoretically it could increase fuel economy if thermal efficiency was improved with more oxygen burning, but the opposite could hold true as well.

What are you going to retune? The engine can calibrate A/F ratio accordingly based on how much air is coming in, as well as using an oxygen sensor to close the loop. It should be a fairly automatic process.

Thanks for subscribing!

Just the video I was looking for. Thank´s. Great video, and channel!

Interesting, thanks for sharing.

Ultimately I would say most are pointless unless the factory tubing is restrictive - I would guess that the vast majority are not restrictive, and that the only "positive" (for a car guy) effect of a SRI would be a louder engine - but this is simply because the silencer box has been removed. They may be of more value once the engine is more heavily modified and requires more air - possibly.

your a beast man. i dont like math much but you made it pretty clear, mostly because you kept most of the variables to a perfect constant state lol. great videos!

I'm always happy to see your videos!

Thanks, please do!

Bro, I watched some videos, they are great, easy and make you wanna learn more and more, but for that single sentence I just love you. STI's my dream car. ;)

You could just leave it as is, or some make splash guards for the filter to prevent any issues.

Perhaps, though turbochargers typically have intercoolers to cool the intake charge.

Hey man, I've stayed up due to being really hung over, and damn.... I've found these videos to be incredibly useful! I'm going to check out UTIs Automotive Coarse. And I've learned a lot already about key parts on a car. Correct me if i'm wrong though. Theoretically to increase Horsepower without Nitrous or another gas/fluid you would need to increase the volume of air (preferably colder air is better due to Oxygen molecules being closer in a higher volume). If i'm wrong ill have to watch these when i'm not hung over but awesome videos buddy! Excited for more to come :)

It acts as feedback to close the loop on the system. If there is oxygen left over, the ECU adjusts accordingly.

I believe you mean large bore vs large stroke, displacement remaining the same. Likely longer stroke would ultimately give more torque, but with a smaller stroke you can typically rev higher, thus creating more power. That said, there could certainly be engines which do the reverse of what is typical.

Very nice explanation of how temperature affects the engine. The manufacture does an awesome job of getting ambient temperatures headed to the engine. A lot of people like how the aftermarket setup looks, but in most cases the air filter is exposed to under hood temperatures. Which makes less power.

Learn a lot from all of these videos; great explanations; thanks

I simply explained the logic hear. It's very likely that many times you won't gain anything. It's important to find (or create) good data showing the improvement.

Thanks man, this video shows exactly what I wanted to know, maybe check out and tell us about the non linear version of the cool air-fuel consumption - hp produced :) great vid!

Thanks Mike!

Thanks man! Keep up what you're doing !

As always your videos and explanations are top notch

Awesome video it all made sense I'm actually glad to have taken chemistry now!

Great videoes!! I understanded that things and principles before but thank to your videoes I can remind them and improve my english as well. Thanks.

they normally do not workas well as they say they do. a buddy of mine did test on a Dino and found some awesome results. (5 runs each filter. giving you the average) he started with a cheap frame air filter, 208 HP. next he used a K&N high flow high filter, 215.5 HP. took out the stock air box and installed a cold air intake made by K&N, 215 HP Toyota Tacoma

Hi, sorry I forgot to mention the significance of the Box housing the air filter in paragraph (1), Assuming the car is moving at 33m/sec., the snorkel will be channeling fresh air into the air Box. If V2 (volume of air when car is moving) is 10.362 x more than V1 (volume of air when car is not moving), and since V1 and V2 are both constrained to travel thru the volumetric space of the air Box, when V2 would be forced to be equal to V1 (the volume of the air Box), P2 would be 10.362x more than P1. Thus the snorkel would perform the same function as a light pressure turbo-charger that would increase the pressure of air by a factor of 10.362 ). But of course, the factor of 10.362 is based on the assumption that the snorkel is capable of perfectly sucking 10.362 cubic metres of air when the car is moving at 33m/sec. I tried it on my Toyota Camry (2.4 litre engine) and the Camry out-accelerates a BMW (2.5 litres engine) from 100km/hr. to 220 km/hr. - taken at a huge risk to my Driving Licence.

Great job with these videos bro keep it up...

Probably so, yes. Check your electrical system as well, plugs/wires/distributor. Obviously if there's a check engine light that would help.

Thanks for the reply. I love your channel, keep up the good work!

If it is moved away from a heat source (the engine). Most cars do this anyways.

Depends if the fitting is the same. If it fits properly it could still work.

For the absolute auto newbie, such videos are a great watch, and we often send them to our fans to share with their friends to get an idea about how cold air intakes amp up car performance.

I simply subtracted 1 from 1.03 to find the percentage change.

I love it, its oil burning tendencies and all. :)

If only I had a vtec and dyno at my disposal. Any donors? :)

You are correct.

My buddy's got the same Acura, he took out his headlight and converted it to a ram-air style intake :p

really nice videos and really instructive . keep it up

Woow i just got subscribed to your channel, im an automotive engeneer teacher here in Mexico and i found your vids very interesting and well explained. PS: im a honda driver too, thumbs up

Ah ok, I understand now. Thanks a lot for all these videos, they are all a big help in understanding what is going on under my hood!

mate i need you for when i build my cars haha this is such a handy channel!! keep it up.. your friendly subscriber from australia :)

Not sure why I smiled immediately when I saw Charle's & Ideal Gas Law sitting on the board. Your videos are excellent as always! Oh, did you ever do a video on twin-chargers? (Turbo & Supercharger) I was actually very curious on how those actually work.

I studied engineering & don’t understand any of these formulas. But is a True engineer. Great video!

I love running my car in the winter at night! My engine temp stays at around 200 degrees and it pulls strong all night long. When that California heat kicks in, I don't even bother because 2-3 pulls at WOT and my engine temp creeps up to 225! And immediately I can feel my power drop off! So yes, your deduction is correct. A sports car, and actually, any car, will perform better in the cold because it is getting cold dense air!

really good explanation! thanks!!

Well, you'd have to know the oxygen density at different tempperatures, but yes there could be a small difference.

Mechanical engineering, most of this stuff I've researched on my own though.

Not exactly sure; could be EGR or just a way to heat the engine up. Warm engines are more efficient.

Thanks for sharing your wisdom. Strangely due to your approach I understood the math. And I understand the logic. One thing though that people dont instantly realise is. More horse power mods you do the more petrol you use. People think that you can get more horse power from mods using the same amount of petrol. Which simply is incorrect. I basically put a 7 inch air intake in my car. The maf read more air in so it put more petrol in 😵 I was able to watch my fuel gauge move literally in front of my eyes. So... I reversed my mod and then put a cover over half my air intake just before the filter and now I'm saving petrol coz the maf sensor has less air over it. So it puts less petrol into the mix. I'm no mechanic I just thought it was obvious to do that.

Perhaps, it relates to thermodynamics.

Well done for simplifying thermodynamics behind the process of air intake! :))) It can be any simplified than this!!! :)))

This guy is awesome he always reply to us:)

I believe EcoBoost just means turbocharged and direct injection. Allows for more power in a smaller more efficient package.

Cold air is more dense, assuming pressure hasn't changed (this video shows that relationship). But at sea level you'll have more air (from higher pressure) than up in a mountain, which would obviously be colder.

99, sorry for your loss!

The decrease in air temperature caused a kind of natural supercharging. As air cools down, it's molecules become less energetic and so it's density increases.this means that the same cylinder volume will contain a little bit more air, and a little bit more fuel to go with it. So the quantity of charge that is compressed and ignited in the cylinder goes up.

I love your videos omgggg so educational!

I have a CAI on my tiburon and it made a slight improvement to performance, I got a very noticable improvement when I added a 421 header and cat back exhaust with it. So they do make difference but by themselves I would say they add 3−6 hp

I wouldn't say most CAIs have no bends. Larger piping perhaps for high revs.

You could likely remove the air filter box and have the same effect. That said I certainly wouldn't recommend it as the filters are likely cheaper.

Thanks for these videos, my knowledge of engines has always been a bit sketchy .

I believe you meant to post this on my nitrous video? Yes, it uses the same fuel pump, which needs to be capable of handling both.

I was just driving in the polar vortex here in the Midwest with -20 f before wind-chill and my ait was -5f and my car didn't feel noticably faster, after that experience I won't bother with a cai again, but they can make ur car sound nice.

If you were to assume that the density of oxygen in air remains the same, as well as the air pressure, then yes. But that's not necessarily true. But there is likely a difference between driving mid-day and at night. Probably small though.

@ralderhali cold air is denser than warm air. Being denser means the same volume of air has more oxygen to burn thus making more power

In my experience, every car is different but on most Japanese cars if the filter is in a place where it can get enough air and isn't to close to the engine sucking up to much hot air them, yes they do make more power at high RPMs.

In the case of my truck all i had to do was simply remove the two rubber hoses going to the intake and run a straight peice of hose to the fitting on the heater hose and the other end to the end where it connected right above the thermostat as a bypass. But like you said it can be as difficult as replacing the whole intake or more just to bypass such a simple system that robs power when its needed for racing purposes.

you should make a video showing us how to calculate the engines airflow and how the relates to airspeed with different sizes intake tubes. I've been looking all over youtube for information on this and i thought you would be the guy to explain this.