Why Cold Air Intakes DON'T or DO Work on Your Car - Motive Tech

The topic of cold air intakes is a much argued one. So many videos on KZbin try and say why they work, or prove they don't work in various applications and models of car and many just show one example. But has anyone ever explained the reasons many do or don't work and when you should and shouldn't change your stock intake? In this Motive Tech we look into the science behind why aftermarket intakes do and do not work and give you the knowledge you need to asses the product and its application. We also have quite a few real world examples from what we have personally done.
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[@MotiveVideo]

What results have you had personally with intake kits? What topic should we cover next in Motive Tech?

[@MafiaboysWorld]

I have personally seen a .4 drop on the 1/4 mile at Eastern Creek with a K&N panel filter in the standard airbox on an AE112 Corolla Sportivo Turbo. 1st week, 15.8, the very next week after fitting the filter and nothing else, ran a 15.4. 👍

[@wobblysauce]

Bingo, nicely done and for some, if you just want to use X brand... you can do that also.

[@RossHollandAU]

On the dyno I've seen mixed results depending on car and setup.. some gains.. some losses... some exactly the same 🤣 gained half a psi once from a intake too...

[@jasondasilva5502]

I am interested to know with some of these cars that run an aftermarket induction system with a cone shaped air filter and also some of the big power Skylines which run no air filter, What effect does this have on the engine lifespan and turbo lifespan ?

[@MotiveVideo]

Most engines break or come out to freshen up before the extra wear from unfiltered particles have an effect to be honest.

[@Scott_GT-R]

Andrew, I love this video, there is a lot of truths there, but also a few inaccuracies. I've been designing Air Induction Systems for many of the big motor OEM's, (US & German), for just over 25 years now and we do a heck of a lot of CFD work on these systems from day one. Granted power is not what we are after so much, its efficiency and economics. But one point I do strongly disagree with from this video is the air flow into the compressor. We have a Gamma ration we need to meet, (the evenness of flow across the compressor face). You use the analogy of a plane engine, but have you ever seen a jet engine mounted facing upward at say 30 degree angle, or even less. NO, they are always pointed directly into the flow as the distribution of the air to the compressor is important. One big tip I can offer you, and something everyone over looks, is for the duct to be as large a Dia as possible right up to the compressor. So that diagram you drew of the Yaris, hold the ~76mm all the way around the bend and neck down to the 50mm at the last minute. This give the compressor a greater volume of air to play with, (from all directions rather than skewed to one side after and 180 bend), and before it is accelerated up and ingested and means the flow speed around the bend is a slow as possible and therefore less restrictive. (Don't forget that any change in direction, cross section, acceleration or deceleration of the air creates RESTICTION). Also swirl is a major factor that we need to manage for NVH and spool up reasons. So much so we even fit spiral swirl generators into the duct before the turbo, (something I have a couple of patents for so far ). But these have an adverse effect of creating a restriction, but something we often have to put up with to get the swirl in order. As for AFM's, one anecdote I have regarding their sensitivity and how it can throw and ECU out, when at Ford we were finding discrepancies in the AFM signal between different filters in the same car. It turned out to be the metal clip that joined the cylindrical filter paper was effecting the signal depending on where it is positioned in relation to the AFM. We ended up adding a small keyway to the filter so I could only go in in one orientation and had the filter manufacture ensure the clip was within +/- 2degrees of the CAD design. Anyway, keep up the great work Andrew and I look forward to your next episode. (I promise I won't piss on that one).

[@SMAC364]

Deep industry knowledge, much appreciated.

[@Scott_GT-R]

@@maiy8786 ideally you want flow as slow as possible, within reason. As for cooling effect of fast air, I've never heard of that from an induction point of view. But any cooling would be out weighed by heat soak through ducts running through hot areas.

[@rob105motorsport]

@@Scott_GT-R - Fair call on the feed in to the turbo. As Andrew hints at, I do imagine there's turbos/setups which are more or less sensitive to the specifics of that. (@Maytricks) If you look at Bernoulli's equation you can exchange velocity for pressure/density (which has a direct relationship with temp'). But you don't get a free lunch as the velocity may notably impact pressure drop and it's impact isn't likely sufficient. This is why you generally want to keep velocities low and flow laminar as Scott mentions. As Scott correctly note, the general conclusions from anecdotal evidence is 'ok'. In addition to your comments, static pressure drop isn't a linear relationship so the linearity is an assumption, density has to be factored in to the IAT considerations against boost response, and open loop tuning means there's generally only a margin of control in the ECU to be able to compensate for cooler air (by jacking fuelling/timing). In any case, really hard to condense a fairly complex topic into an easily digestible format, so full credit to Andrew for the video.

[@edh7492]

Well Scott that was pretty comprehensive, cheers for bothering to share your knowledge.

[@Kiwiluv4tunes]

Heck, very informative. Cheers much appreciated.

[@kpfalconi]

You didn’t include making sure the cold air intake tube being red. That adds 100 HP automatically.

[@tomtdh4903]

😂 used too in my saxo 1L

[@mexicanbandito]

Damn that's some funny dad logic we would here when we would slap stickers on our motorcycles as kids. 10 hp right there

[@gabet3754]

That’s true

[@alastairdow4400]

That only works on body colour

[@bimmermac]

The upgrade to red is purple with a sticker.

[@t0aster_b4th]

The man behind some of the wildest GT-Rs in the world teaching us things? I'm paying attention professor, please carry on!

[@4RMS7TRONG]

From what I've found. Stock systems are designed to give mostly mid range torque for drivability and not much top end. A cold air kit tends to give you more top end at the cost of mid range power. Although this isn't the same for all cars.

[@stevenmcgeorge1983]

This is the best video about intakes I've ever seen. Thank you for putting the work in.

[@FirstContactX]

My JZX100 lost nearly 5kw at the hubs taking off the stock airbox and throwing a k&n pod filter off the MAF. Back to back dyno runs minutes apart. Of course the pod filter sounded 100x better which is all that really matters.

[@dimmacommunication]

lol

[@dotti1203]

that's what i tell most people, change to an aftermarket intake for noise not power

[@dimmacommunication]

@@dotti1203 Also stock filters air way better.

[@krispykruzer]

Agree, went back to stock too. But I miss the intake sound...a lot...

[@rabidsminions2079]

So you are willing to loose 5kw for sound?

[@MitchTube]

On 70-80s era cars I think high flow k&n filters made a noticeable difference. Modern cars are much better designed so gains are negligible without more mods

[@mathieucayer3942]

100% agree, I had a tuner tell me to install a new suzuki air filter on my race gsxr1000 because it actually has a better power band vs a k&n which is mostly peak power designed!

[@aliyahu76]

That's because of the computer programming! Old cars had no computers

[@thomasmatarazzo198]

K&N products are garbage in every way. Still blown away how they still have a standing in the automovie community. Nothing to do with the topic at hand. Just thought I'd put that info out

[@harveybrooks2597]

@@thomasmatarazzo198 So you prefer throwing paper filters away?

[@thomasmatarazzo198]

@@harveybrooks2597 No other companies make better filters

[@drdesmo8489]

There are people who can explain technical info and people who can’t !?! Andrew is a Natural Teacher, you can’t underestimate how important this is. Not sure what topic next, but I know you’ll bring it to us the best way possible ! Thank you very much.

[@anthonysharpe5104]

This is the best discussion and explanation of this topic that I’ve watched. It’s so obvious when you think about it that a dyno with a big fan blowing at a constant speed into the front of the car cannot mimic the actual on road situation where the vehicle is increasing velocity through the air as it accelerates. Great work.

[@staciecarverd8136]

Excellent information! Nice to also learn of some of the tricks to what may actually make one intake work vs. another. You really have to know what you're working with, your vehicle's needs, the limitations of the factory parts, their original design parameters, and have the means to test the changes you've made to determine if it was necessary/beneficial or not.

[@benphillips3915]

Thank you for that information, you helped me solve an issue on my truck that I wasn't seeking the answer here for. The AFM signal was changing the timing of my truck which was causing a check engine light because of timing... it made perfect sense when I realized the K&N air filter kit came with an air filter to put over the MAFS.

[@153eddy]

Great video. The well explained details really helped to understand what really happens in the intake system. Thank you

[@carlob517]

great video Andrew very detailed , owned a 93 R33 GTST the best intake mod by far was a front mount intercooler , you raised a good point about air flow and the air temp thru an intercooler , on a warm/hot day your car might feel sluggish which with a standard intercooler is indeed very noticeable , much less noticeable after fitting the front mount intercooler i ran als K&N but to be honest when your using only 10psi no difference except the cost saving

[@petequinones3454]

The sound you get from a aluminum CAI on a 90's Honda is worth the price of admission alone...sooo good. 4hp+ is just a bonus.

[@newemoboy1]

I could care less about gains, I just love the sound lol

[@charlies418]

Best explanation so far! A lot of mods actually reduce power! I know a garage that cut a bonnet scoop in the bonnet of a Subaru where the intake was. Logic tells you that more cold air equals more power. Bizarrely the intake temps increased! On another subaru they fitted a high-flow intercooler which cut the intake temps by over 50% on track. There are many subtle mods you can do that don't increase overall power but improve throttle response like removing the turbo muffler on Audis.

[@asalouros]

That was an awesome video. Learnt so much. Thanks for posting this!

[@deborinquen13]

This video was amazingly informative. I, the man with no patience, sat through the entire video and am leaving better informed. Thank you.

[@simbo5681]

Would be good to try a drop in performance filter on that 996 to see how it compares to the cone and stock paper filter. Personally think if it’s a well designed intake system a drop in filter is usually the way to go especially with NA cars as the penalty for sucking in hot air through a cone will loose power

[@Luigi13]

This has been the best explanation that shows what is crucial in any intake system and not just the flow of air. Thank you well explained and it is very logical.

[@TubeThrill]

Very good piece. Could you, at some point touch on the particulate sizes of grit permitted by some aftermarket filter, and the after effects to the engine, vs the very good filtration of the stock paper filter?

[@hotflashfoto]

That made so much sense! I noticed you didn't wade into the pros and cons of oiled air filters, such as oil on the MAF and/or particle sizes actually filtered out. That would be another good video.

[@arupdas4237]

Amazingly informative, best video about intakes I've ever seen. Learnt so much. Thanks for posting this!

[@chicoresch6373]

What a great informative well put together video presentation! Seriously 10 /10 !!! I'm no mechanic but I understood just about everything you were saying... 👏👏👏

[@ONE_GEN_X]

Thanks for sharing your knowledge. I learned some great information today.

[@Ziccolumbia]

Learned a lot watching this, thanks for posting.

[@zbeasty]

There was one a few years ago with aftermarket intakes for VW and Audi. Can't remember who the manufacturer was but they changed the thickness of the piping. OD was the same but ID increased. People who had the original version raved about how good the intake was but those that got the revised model absolutely hated them. Fuel trims were out, they ran roughly, had hesitation on acceleration. All because they ID had changed by 1 - 2mm which meant that the MAF signal was messed up.

[@chrisg4rr377]

I think I've learnt more from Motive videos than every other channel. I still can't understand how they don't have that many subs

[@jimfallowfield7028]

The most logical explanation I have seen for CAI. Fully agree with measuring with a vacuum gauge to detect restriction. If CAI's worked across the board, the companies that sell them would demonstrate this.

[@bugsnstuff5643]

Very good info. Here in the US most every "cold air" intake that I've seen isn't sealed up at all. Just pulls hot air from whatever corner of the engine bay it's mounted. All show n no go.

[@travistydings3150]

That would be a short ram. A cold air intake pulls air from outside the engine bay

[@Formula1-Dave]

Beautiful presentation. Thanks for sharing this information

[@willjr2520]

Probably the most thorough explanation and reasoning for me not to get an aftermarket air intake piping, but get an upgrade IC on a stock car in a desert climate.

[@snape1464]

I watched Evolve MS's video on their Yaris kit and it looks descent enough. Might not make a big gain, but it's an easy way to get nice noises without losing power as you'd get with an open pod filter. Looks dope aswel

[@ervmister]

I have to say that you did a Great job explaining this to us. thanks for the very useful information 👍

[@jameslane2326]

It sounds like i will make most of my gains on a stock engine by simply adding a K and N drop in filter to the stock airbox instead of doing after market

[@TD5rage]

Great video and very informative. I’m glad someone did what I was thinking. 👍

[@michaelallen2501]

I've increased the size and flow of every part of my intake tract. The last bottleneck left in the system is the intake runner in the cylinder head and the intake valves lol. But a set of AFR heads aren't in the budget just yet :-(

[@mathewhunt81]

i almost didnt watch because 30 mins long but so glad i did. very informative, never boring, and extremely useful information! subbed !

[@dasfahrer8187]

Comprehensive and useful. Thanks for posting!

[@bardstables8909]

This was an excellent video. Some things I hadn't even considered is now something I need to think about before replacing mine. I figured I knew what I was going to do. But now..... time to do some more research I think.

[@DwightTSchrute]

Thank you for such an informative video. Seems that an upgrade in the intercooler is more important than a CIA.

[@christiansincich7226]

I love being a chemical engineer who’s taken transport phenomena and understand the equations necessary to back up all the visual assumptions! Also “turbulent” is definitely the way you described, but the smooth flow is what we’d call “laminar” flow. Helps out with solving for equations and such like Reynolds number and such🤓

[@helicoptera75]

Well explained, i understood every concept, well put across, thankyou...

[@2006chunming]

Oh! Wow ..didn't know changing the air intake and the intake piping on the A90 supra yielded no results. Thank you so much for the informative video.

[@rickylah69]

wow the knowledge is deep. thanks, i learnt many things here.

[@renegadeGM]

After seeing this. It makes sense. Thanks for sharing. You should add info of stepping up to having a "Y-pipe" intake with duel intake filters when finding out a single intake filter is becoming a restriction.

[@sbfhawk4343]

Anytime I have used AEM cold Air intakes with Ceramic coating do create about 5 Horsepower increase thru out the range. Now when you tune it though and make huge changes to the fuel and Spark delivery then it really starts to produce over 10 to 15 HP Seen it done it dude on a Dyno.

Thanks for clarifying! This is exactly why I've been standoffish about buying 'cold' air intake systems that just feels like snake oil to me. A lot like the intake tornado rubbish from years ago

[@GForceVRX]

Very well explained, thank you!

[@stevenlefebvre2991]

Thank you for all the information I learned a lot. Not just somebody trying to sell me their intake kit.

[@jcass1970]

I can say that a lot of what you said is spot on. I installed an Injen CAI on my first Audi C7 A6 3.0, and didn't see much difference in hp at all (if any). When I purchased my second C7 A6, I bought a K&N replacement for the stock filter, added a chrome intake pipe, and left the box alone. I used the same exact chip as I had on the first Audi, and everything else was the same. Never dyno'd the car, but the hp increase was definitely noticeable, the launch was way more aggressive, and the torque was up there. I don't exactly know why I purchased a CAI originally, and the cause could be from several different factors (manufacturers influence, because they looked cool, or too much Jack Daniels), who knows. The 2nd time around, I thought about it for a minute and figured those engineers at Audi know what they're doing, and I looked at the design, and it all made sense. Air is forced into the air box from the very front of the car so why did I ever take out the box and have the air come from directly inside the hot-ass engine compartment. I could kick my own ass for not seeing it earlier, but that's how we learn, I suppose.

[@kylebell2365]

Thanks John…you just convinced me NOT to purchase an aftermarket intake for my 2022 Genesis G70 sport prestige. I think I’m going with a Nishimoto intercooler.

[@TommyLuptak]

Brilliant!!! I was a math professor and I was very good at information delivery. You my friend are brilliant with your delivery!!! Bravo!!!🎉

[@CarChris82]

very interesting vid I have a induction kit and my friend doesn't we both have the same cars and are both stage 1 mapped but mine pulls away from his as we increase our speed a i think mine can breath better at the top end of the revs

[@boostbogan]

Keep up the tech videos, these are fantastic

[@ShaunButterley]

This is super informative, thank you!

[@victorvaldez6785]

Thank you for this video. It helped me a lot.

[@earache_srt8790]

Very well done explanation video. This video helped me understand some of the success that I have had building a cold air intake in my street/drag truck. One of the successful things that I had not understood was the placement of the mass air sensor. I had cut a factory mount from an intake and put it where it belongs in front of the throttle body. I have learned that even the direction or orientation of a sensor can contribute to success. The mechanic that did the motor swap had mounted it in the end of a conical air filter. Another part of my success was deleting the a/c system. With the decrease in drag from the compressor and the removal of the condenser gives a clear path for air through the front grill. These changes showed up at the track keeping in mind that the density altitude was better at testing the truck went from 9s to 8.7 in an 1/8 th . More than 3 - 10th of a second increase ! Thanks again for this video. As I mentioned above it helped me understand the improvements that I had made. I already knew that it had made a huge difference but, now I understand why it worked so well.

[@alexcarrillo5187]

So what's better a stock 2011 mustang 5.0 intake or airaid cold air intake

[@HeinzGuderian_]

Cold air intakes work great as long as they are not sucking hot air from the engine compartment. I use a Weapon-R system on my Dart and have it connected to the factory air box so it draws cool air from inside the fender. Works like a charm according to the IAT sensor and the Dyno after tuning it.

[@porjos]

I just watched your "Why Cold Air Intakes DONT or DO Work on your car" video. You put in real thought and analysis, backed by real world data. There's so much conflicting information out there - your video stood out as an unbiased understanding to CAI. So thanks :)

[@fawnsans]

okay robot

[@jamieholyoak4462]

The CAI walki one for VE SS added 15kw atw dyno run 40 mins apart. Worked well, sounded decent.

[@jeremycolon3866]

My personal experience is with a 2011 F-150 with the gen1 5.0L Coyote. I added the K&N cold air system to it, and although I have no clue how much HP was gained it was definitely felt. As well as MPG increased by 1.5, pending reasonable driving. At one point I decided to go back to the stock intake with a K&N panel filter for a more sustained MPG. The MPG and HP were barely over stock levels. Needless to say I went back to the cold air system. Now 8 years later and with 225K on the truck I'm still happy with the system. The only bad point is that the oil used in the filter does go all the way through the induction system. That means it will build up and cause flow issues in time. Which in turn means complete cleaning of the induction system every so often. Would still recommend it for this ap though as it does work.

[@fdroepman8351]

Thanks for the real world information Jeremy!

[@Jeremy-sf2xf]

This was one of the best informative video i have seen on this.

[@nikosraptis1985]

Best explanation ever !!! Thank you very much!

[@larsjrgensen5975]

A tuner company for my car sold MAP sensor hoses made with a small drilled hole in them, so a small amount of air going to the sensor leaked out before reaching the sensor. The ECU though the engine was boosting too little because of the lower MAP sensor measurement and the ECU then adjusted the boost higher then stock boost to compensate.

[@BulliKid]

A great explanation no one talks about. Thank you!!

[@LXBR58]

Explicação excelente!

[@1michaelricci]

Great video! I learned a few things and now curious about my 2021 718 Cayman T. I’m looking for better sound and more peer would be great. However, not my primary goal. Any recommendations on improving the intake sound, turbo and BoV sound on these 2.0L boxers?

[@k9-unit-australia275]

I just changed my cobb pod filter to a grimspeed dry con panel filter. I recently put in on the dyno and had a 9hp gain before tuning even started. So il be staying with my airbox & panel filter moving forward

[@larsweinand4035]

Great video! Thank you! You mentioned mods/solution to bring cold air to the flap of the GR Yaris airbox. Do you have any products/links? Also for the stock snorkel.... Also wondering why the stock snorkel has opening at all.

[@RadggsAutomotive]

I've used several different brands, some made by same parent company, and have only seen decreased mpg, sometimes a better feel. Overall not worth the bucks for a straight stock vehicle. The only advantage has been the ability to clean and replace. Info is king, thanks for the video.

[@usiak13]

So, from what I know and from this video, best way to increase power of my NA RX-8 is to lower temperature of air. So ram air duct it is...

[@FastAndCharged]

Thank you for this awesome video!

[@michaelclark3192]

This is very interesting, especially with regards to the air flow meter. My car, MK7 Fiesta ST had a Cobb intake installed by the previous owner that constantly threw a code, lean on idle that went away when switched back to the factory intake. This was because the cobb intake moved the location of the air flow meter from very close to the filter in the top piece of the airbox to higher up in the intake pipe. So the long term fuel trim was way over 50% all the time causing the engine light to come on. It was also located after intakes from the carbon canister which may have had an effect. What we have found out is that apparently for the US spec Fiestas, their map does not use data from the AFM, just map sensor whereas the Euro spec which we get in Australia does use the flow rates for the tune. And on our Fiesta group there is sticky notice for that warns people to not buy any intakes from US manufacturers like Cobb, K&N and Mishimoto as they just throw codes. It doesn't help that most of these companies never tested their intakes on non US cars so Aussie retailers who don't really do much research still sell them to unsuspecting customers.

[@modfoxv10]

intake manifold vs what kids call an "intake"

[@newtongsm]

That normal with 99.9 % aftermarket parts manufacturer they don’t even test for a month driving the car on road and then make fake claims

[@N6ADC]

This is the first video of yours I’ve ever seen as of today and it single-handedly won you another subscriber. Douse the opinions of vehicle performance upgrades with kerosene and set them a conflagration with ingenuity, knowledge, and science.

[@pat36a]

Air meters , we found we could "tune " a car sometimes by rotating the Air Flow meter in the intake system. Especially there was a bend in the tube w/in 6" , ether in front of it or behind. The meters themselves were in a 6" straight pipe . Air hugs and compresses a little at the top or outside of a bend , inside of the bend it slows down and looses pressure becouse of the air compression on top. It takes a few inches of straight pipe to even out .

[@gavinsmith9022]

Fantastic video mate, i learnt some new things from watching.

[@M--76]

Seriously good information!

Good vidéo, very informative. Thanks

[@frylock4677]

Good video, I got the info I needed.

[@nitrokyosho]

K&N were being used on our military vehicles and helicopters during the desert storm war. I have a 2022 shelby gt 500 the stock air box is better than any after market junk you will buy ,but i do use a after market filter.

[@PureEvolution]

I got the AEM cold intake for the evo x as its one of the best and closest to OEM as you can get but letting a little more air flow around the filter and also a smoothing intake to turbo pipe this has made spool up times a little nicer feeling as for power i am not sure with my butt dyno but i think there was a video out there few years that did get around 7 hp but dyno could get that from having the straps looser and my intake temps dont seem to go up so fast when in traffic being a little bigger and better contructed box.. great video and very well explained too alot is what i researched before getting my intake other year...

[@omgness1234]

But you get no cool spool noises from it being in a box :/

[@choongstarr3809]

This guy is my idol. Thanks for all your wisdom brother. Love your videos.

[@jacquesgold]

Brilliant information. Thank you

[@simonwatling2203]

so refreshing to see a sensible approach to explaining intakes... didn't think i would learn anything but i ended up learning a lot... no mention of the sound, which is arguably why most people will install an intake... even if my car made less kw with a pod filter.. i would probably still run one just for the visual gains :P

[@dlyle]

GOOD FACTUAL INFO!!!!! another great watch

[@JoshuaWilliamsMA83]

That's why you must install the included stickers with your intake. The stickers increase the horsepower of your motor even more making the intake more effective.

[@wrigman]

Most late model cars come STOCK with a cold air intake. They draw cold air from behind the grill or inside a wheel well. The after market “Cold air intake” sits under the hood and collects HOT air. It may be less restrictive, but, it is anything but cold air. I run a stock air box with either a AEM dry drop in filter or a K&N oiled filter to open things up a bit.

[@joshburts1044]

I have a 2010 toyota tacoma, the first mod I did was one of those "cold air" intakes. Yes it's less restrictive and you can hear an audible throttle sound. The down side is there wasn't any noticeable mpg difference no power difference. I'm now planning to swap that intake out for more of an actual cold air intake, hopefully we'll see an actual difference.

[@Lunatic_Lou]

Great explanation of how things work

[@TechViewOpinions]

Great science behind your discussion.

[@pdogg310]

Thanks for the lesson

[@noelmclean936]

Best explanation ever. Thanks mate

[@mattipuh]

what custom upper intake pipe did you show in this video? curious.. . thanks for great info on GR intake flow & dimensions!

[@peterwho9380]

I've gone through a K&N drop in filter, K&N Black Hawk CAI, Injen Evolution CAI and then JLT CAI with a 2018 IM for my 2016 S550 and TBH the best power I felt was the basic drop in filter where I didn't lose any low end torque and acceleration. Now I only have power from the mid to high range and low end it's kind sleepy! I might go back to my stock intake and leave the 18 IM as is.

[@skippy2987]

It's worth noting that a sharp edge immediately before a turbo (i.e. if packaging requires a 90 hard up against the intake, like early Subarus and a few euro things) puts up to half the compressor in a lower pressure zone, affecting overall compressor efficiency (effectively the turbo is operating at a higher pressure ratio). I read a paper on this, the authors designed a roughly banjo-shaped fitting that allowed a bellmouth to be used and fed efficiently from one side (kind of like an old-school carb filter housing that has air piped in from one side but still has even flow around the carb. Like that, but much more compact and actually with a big enough inlet hole). The improvements in compressor efficiency were measurable and useful. Also it sounds like the filter on your GTR was limited by airflow area. Once velocity approaches sonic sucking harder doesn't result in more airflow and just results in more vacuum. The area for airflow through the filter (minus any boundary layer effects in the filter) was less than the pipe. If it was a *shape* problem you'd note increasing gains up to that point rather than the wall that you got. I'd wager a bigger/deeper filter in the same spot would get you your 50hp back. If such a filter exists... Also Also re air temp on turbo cars: ALL SUBARUS NEED INTERCOOLER FANS. I put my 280,000km otherwise completely stock Gen 4 Legacy GT down the strip and ran 4x 14.9 second passes, and I largely attribute that to the intercooler always being cool because I put a fan on it.

[@Gryphus-R]

Great great video. Thank you. Finally some arguments based on evidence and not just buyers remorse. I'm a GR yaris owner and I don't want to touch anything going into the AFM because I don't want to reprogram the ECU yet, but I'm interested on the cold air piping going into the OEM airbox that you show around 23:49 and also the duct you mention at 23:56. Could you please share links to any place which sells those? I noticed it's 3d printed, so the STL would also do.

[@jxyzbyyy8567]

Thanks for the lesson. Very informative. Also your lesson on the blood flow on the turbo was probably pretty accurate, lol.

[@jamesstewart3771]

I had a 2003 Toyota Maytrix that I put a AEM cold air intake on . I never had it on a dyno, but it definitely upped my top speed . My top speed went from stock 128 , to 132 mph .

[@SMAC364]

A highly informative video. That point about the intercooler air temp drop vs the cold air intake, never considered that fact but I have ducted my intercooler as per your 'best practice aero' video, such a great video. Regarding air movement through ducting, I read an article which stated that if air is to be ducted, by ram effect only, a 90 degree bend equates to around 36 feet of straight ducting due to the direction change. This seems feasible and it would be great to hear opinions on this.

[@tepidtuna7450]

If you're interested, there's a popular book by Corky Bell called Maximum Boost. Page 58 has great info on airflow through heat exchangers.

[@chimnino]

My Monster Sport carbon air intake on my Suzuki Swift Sport 1.6 (NA) brought it from 130hp before tuning (after mounting, so a little loss without tune from the 136 stock), to 154 after tuning. Quite amazed by those numbers from just an air intake! No other engine/exhaust mods done!

[@billmago7991]

Thank you for that information 👍👍