WTF is Aero? The Basics Explained and Myths Revealed Pt1 - The Front End

Aero is a huge topic when it comes to cars, but we've gone and explained the basics in a way you can understand. In part 1 we cover the front end, including cooling, bonnet vents, diffusers, splitters, flat floors and more. Special thanks to AMB Aero.

[@TheBondy666]

What a nucking futs episode Andrew 👌 just smashed 10+ years of misinformation rolling around in my head I thought was correct, really enjoying the the technical episodes lately keep it up!

[@tepidtuna7450]

I took the undertrays off my A5 2L turbo for a diverter upgrade. I didn't put them back on thinking the drag assist was neglible at Aussie speeds. I was going to put them back on eventually. Then I upgraded the stock intercooler to a massive Wagner competition unit. I didn't see the performance or IATs I thought I would get. THEN I put the undertrays back on, holy crap did it pick up torque, power, and throttle response. Your description of air routing through the engine bay and heat exchangers really woke me up to the differences it makes. Cheers.

[@ftovr2957]

I've been thinking about custom ducting/trays for my car since they are long gone, timely reminder about how necessary they are!

[@Master_Psyper]

You’d think that after 4 months of this video being out, you’d stop seeing the lifted hood. I always thought it was for clearance, talk about educating myself. Awesome video guys!

[@eckomob6898]

I've watched this video at least 20 times by now. Excellent work!

[@shadowprice8100]

After 15 years of car "enthusiasm" I thought there wasn't much left to learn... then this comes along and funnels that notion right upside down and through my under tunnels.

[@nocrustracing]

There's always more. Always. I love it :D

[@LucidSnapshots]

You probably know more about aero than the video. The video breaks laws of physics many times with the explanations. The mods do what he says but not why he says. Not at all

[@gt4lex]

@@LucidSnapshots I'd be curious to know what you think is wrong in there because it all seems pretty right to me. A successful race car builder with championship wins is vouching for that video as well.

[@sierra715]

This is actually a lot of what Julian edgar has has been talking about in his book and on his youtube channel! Apparently the best way to improve a cars aero performance is just an undertray, it reduces so much drag and lift that its a very noticeable affect on the car, and its just an aluminum sheet.

[@ilham7345]

does pvc sheet works?

[@lotuselansteve]

@@ilham7345 If rigid, yes, any rigid flat material will work.

[@benridesbikes6975]

That was bloody excellent. Currently getting more serious about sprints in the R33, and this was jam packed with just the right level of depth that I needed, and it was digestible to an enthusiast the whole way through. Excellent work mate!

[@ress87]

Man I've been looking for some quality aero info since Kyle Engineers stopped uploading! Functional aero is probably the most cost effective mod to a performance car.

[@silverfox81]

Very informative. Thanks for taking the time to do these regular videos. This is one of the best channels I've discovered for petrol heads. Hello from Scotland.

[@John-rw9bv]

These Motive Video videos are so good, i learned a heap from the dry sump video and even more with this aero video, thanks a million :)

[@scs15]

Really good video. One of the best I've seen on racecar aero. It has taken me years to learn and apply most of the info here into my car!

[@5thgearouttahere]

Highly recommend Simon McBeath's book to anyone interested in racing aerodynamics.

[@tommylyeah]

Hey, thanks!

[@0xGRIDRUNR]

I learned quite a lot from this video, love this series!

[@daver9823]

This video is extraordinarily useful. Exactly what I was looking for. A lot of this confirms my instincts, but I’m now less aerodynamically dumb than I was before watching I’m grateful

[@stevenharpervw]

That was super interesting, watched it all in full. I’m not looking for more speed but more fuel efficiency, loads of great info. Especially the air halt hat gets trapped in your front bonnet and slowing down the air into your inter cooler . Great video Andrew !

[@MadmanJnr]

Well worth the watch! "This could be a 10,000part series..." I was think surely not but yes, yes it could be. Such a great explanation and im looking forward to the rest of the videos

[@neilvenners3309]

Great insight thank you! We’ll get an answer to your Leroy conundrum soon enough as a body is being made at present.

[@gokhanozarslan8999]

You ‘re the best .This is the very well and simple expleain of aero .Please keep going .

[@shizukesajdm]

What a fantastic video! From an engineering student myself, really really well structured and informative.

[@DRIFTSUNRC]

so you see people removing bonnets to aid with overheating. how would no bonnet affect things?

[@LucidSnapshots]

The bonnet needs to be there to be smooth exterior as well as actually ducting air around. The vents are there to mainly create low-pressure zones underneath as the air travels above them which basically sucks out their air. (Not high-pressure areas like he explains). The air on top doesn't want to go back in the bonnet really as that would be like adding thrust to the car lol

[@lindsaymac911]

Thanks for a great video, you explained very well and concisely.

[@lukemcguire2532]

M8 really enjoyed this video and helped me to Design and understand what I need to do fro my road/track car. Looking forward to the rear video Thanks 🏴󠁧󠁢󠁳󠁣󠁴󠁿

[@Nismo-gy3wz]

One of your best videos Andrew, very well explained.

[@ChillDude01]

This was a great video. Thanks for producing it!

[@flytoday]

you are almost there, its angle of attack that creates down force and the shape of the wing that stops the separation of air flow from the wing. Bernoulli has little effect on lift apart from separation of the air flow from the wing. You can test this by blowing on a sheet of paper, blowing underneath requires a lot less effort compared to blowing over the top.

[@MotiveVideo]

We're keeping it simple. And explained both of those principles. Remember most people watching know zero about aero

[@flytoday]

@@MotiveVideo Bernoulli principle tends to confuse a lot of people. angle of attack makes a lot more sense when you use the example of rowing with an oar

[@MotiveVideo]

We did explain that theory as well

[@MotiveVideo]

We explained that theory but people need to understand low pressure created in tunnels and diffusers

[@JimmyLLL]

There is going to be some hacked up front bars and bonnets this week.

[@csk485]

This was a legitimately brilliant video, I learnt a lot and look forward to future entries to the series. Keep up these killer videos 👌

[@maestromiles1]

all these videos are so great! Thanks so much for putting all the work in for these excellent and informative videos!

[@explore_n_4x462]

Step 1. Buy whole bunch of ebay spec "aero" bits. Step 2. Watch Motives WTF episode. Step 3. Throw out all ebay spec crap lol

[@MotiveVideo]

Funny story. The centre bonnet vent started life as an eBay generic vent that we modified.

[@wobblysauce]

@@MotiveVideo That is it, some people go ham, but just need some good basics to get the result they are after. Like on a cold day you can cover up the holes full or partial depending on the data with some tape.

[@jacobmoses3712]

Thanks Andrew. Great explanation

[@iliketorockrock]

Thank you for the info, looking forward to the next part!

[@martynpotter21]

Thanks for this Andrew. I found it helpful and really educational 👍

[@adamloader9534]

Thanks. Good introduction to such a detailed topic.

[@TheGinger1]

I enjoyed that. I look forward to the next one

[@Ka1ashOffdog]

I've been increasingly more interested in aerodynamics and have been wanting to get my hands on a CFD program to mess with potential aero ideas for my R32 GTR, Mostly to solve the front end lift issues at high speed & also to see how much drag one of those fujimura carbon gurney flaps make lol

[@iffy801]

Have a look at OpenFOAM. You'll need a modelling program as well to create the geometry. This will likely be the most difficult to do since other than correct dimensions etc you'll need to decide the fidelity of your simulation and how that will relate to the level of detail of your model. Without access to some significant processing hardware you'll be limited by your computational resources so keep the model simple. Of course this has limitations in that with the low fidelity you won't be simulating some of the interactions of smaller parts of the car... CFD is a harsh mistress!

[@Dutch1982]

Best practical aerodynamic video ever.

[@HanshinImports]

Very Cool Video with lots of useful information!

[@seanissomething]

Well, that was bloody fascinating

[@slackwire_55]

A lot of factual and useful information. Street Bandito also did a video on aero that compliments your session with not much difference. Check them out. They added tunnels to create the high and low pressures whilst taking the air around the front tires.

[@michaelganter8952]

That was very informative. Thank you.

[@spooler7828]

Great video. I have a front end lift issue I need to work on myself.

[@pippinosborne2372]

Excellent video, thanks. Pip

[@juddy953]

Will u do a video on brake ducting?

[@captainobvious9188]

I think one of the reasons why the R35 GT-R was so much quicker then expected is because of Aero. You have to accelerate the mass and apply force to counteract the drag. The power and traction element allows it to get past the range where its weight mattered a lot less compared to drag, but its contemporary rivals all had a much higher C/D.

[@muskytuned]

Great Video! Where did you get the pair of louvers that are in the hood?

[@richardneale6058]

Really interesting video opened my eyes to a new element in racecar building thank you Andrew Hawkins 🤟🤟👌👌

[@martokisful]

That's what i call introduction to knowledge, thank you!

[@animaze8043]

Its amazing how much you can get out of a simple fluid dynamics principle: As channeled air passes through a section of different cross sectional area, the velocity has to decrease or increase to keep the mass flow constant. With a diffusor, the area increases and velocity decreases. That reduces the dynamic pressure and the total pressure in effect is decreased, creating a low pressure zone underneath = downforce. I wonder, however, how much active aero would help some of the problems you see here - and if turbos would benefit from something like a small reverse cowl to suck air from. In general, fans have been used on racecars to make them quite sticky to the road - are they completely banned from time attack?

[@boostedbuiltgarage]

Great info 👌

[@Kyrazlan]

You showed the bonnet being raised and the pressure zones on the white board but can we see CFD proof of this actually happening? The is a high pressure zone there on unmodified cars because its a sharp angle change but what happens when you reduce that angle with the raised hood? isn't there a high pressure zone at the firewall from all the air coming into the engine bay?

[@dmanero]

This was very informative and explained very well, differently learned a bit more.

[@charleswarland2800]

Nice 1 andrew 👍

[@Keys.Bradley.Racing]

I feel more educated now, good video 👌🏻

[@TWKofSWE]

Cleetus actually ran Leroy in a windtunnel. And they calculated how much faster it would be with a body on it.

[@MotiveVideo]

We know. We're friends

[@OGNISTYSZKQAJDII]

if u want stock car that is preety grounded at hight speed astra G in wagon ive done 170 (1,6L) and actuall issue of this car was rear end lift when cornering without accelereation if u pedal to the metal on the corner balance was keeping rear end grounded stock front lip is actually designed preety well and front vent is almost fully covered with plastic (u can take it off btw) i gotta say that ive drive it hard when it was 30 C outside and radiator fan didnt have to start blowin,g coolant was keeping 80 C so taking off that cover isnt necesary at all that limits air under the car and pressure in engine bay no lift babe but its actually slippy on low speeds ive crashed it at 40km/h when understeer kicked in half way the corner but anyway preety fun car i cannot recomend compact or coupe ive never drive one but those have even more weight on front and rear end might be a real problem

[@iamnoob8925]

Exactly what i needed and Just in Time.

[@barrysheldrick2704]

Another brilliant video, thank you. One question, why not put bell mouths on the holes in the bumper to the air filter? Would this help to feed more air into the filter with less drag? Or maybe even mean you only need one hole?

[@Toycoma]

What about more info on the side skirts?

[@foxpsi]

Really great vid very informative never knew just how much are affects the car.

[@victorrodriguez5332]

I have shared this video with my Nismo club here in costa rica and everyone is getting mad!!, greetings guys!!

[@MotiveVideo]

Mad as in good or mad as in their theories are wrong and they're upset?

[@victorrodriguez5332]

@@MotiveVideo hey no no, mad as goooooooooood you guys really know what you doing!!! actually we built a S14 with RB26 following many tips from your videos, low budget ofcourse lol

[@thephranc]

I thought the canards were to create a low pressure vortex to draw air out from in front of the tire?

[@snarey54]

Awesome content, can we find a sponsor for some good whiteboard markers though ???

[@MotiveVideo]

The markers are fine. People watch on small screens

[@idokwatcher2062]

7:08 that guy did not read 10,000 page book on aerodynamics :)

[@Dirka696969]

Reminds me of a lesson you gave around ‘96😁

[@MotiveVideo]

?

[@upurkilt7246]

Andy forests stormtrooper fuck yea. he has done an amazing feet with that car. In the beginning it was a duel purpose car drag and circuit. It was the fastest subaru in the 1/4 mile 7.74 at 179mph at one point also doing circuit racing and doing super lap scotland was a very diverse car. No its circuit only and looks amazing.

[@jessekleidon9503]

Dude, take a sub. Seriously good channel.

[@16vg60mikey]

Well done video!

[@yowhatsdoin8838]

Does this mean reverse cowls are bad for cooling at speed ???

[@MotiveVideo]

Depends how it is ducted underneath. If it goes to a sealed airbox for the intake, then no.

[@Chaddyp100]

Great video!

[@weduhpeople8504]

I plan to add a chassis mount splitter which mounts to the front aluminum crash beam on my 2018 Honda Civic Type R which is currently at 686hp 550ft lbs. I did notice the increased front end lift at faster acceleration and higher speeds which feels less stable feeling from the input of how loose the steering is. The chassis splitter should help alot. Possibly a 4” extended splitter. I had a custom cai made to reroute the intake pipe going to the 4” inlet on the Garrett g30-770 compressor inlet. It is rerouted down right in front of the passenger side fog light which I replaced the mostly closed faux vent with one that is fully opened diamond mesh shaped grill. I also thought it would help with engine heat soak which the Type R is plagued with running hard at the track making the ecu pull timing. I have the same open diamond mesh open fog light grill on the driver’s side but do plan to install an HKS Type R specific oil cooler that is designed with aluminum panel ducting to direct air to the oil cooler. Honda engineered every aspect of the car with aero in mind doing multiple duties, brake cooling, sealed flat floor, fender side vents to get air out of the engine bay, rear wing, lower front lip, rear diffuser, vortex generators on the roof to help route air to the rear wing flap for more down force. I did also replace the middle wing flap with the Japanese Varis carbon fiber wing flap with an upswepted rear blade edge, but been thinking of getting larger Varis GT style wing for more down force. I’ve also been thinking of having aluminum panel ducting made for the front center opening of the front bumper to have air go to the radiator, air condenser, and 27 Won fmic more efficiently with less bleed around them.

[@jasaircraft]

Great vid!

[@Popes_Projects]

Loved it!

[@Trusn8per]

Gonna go put holes in my bonnet with a pick axe

[@MotiveVideo]

Speed holes

[@Crazy4wheels]

👏👏👏👏

[@namedisclosed1849]

Fluid mechanics, Bernoulli’s, frictional losses leading to pressure drops, turbulent laminar flow, Reynolds number, surface roughness. I used to sledge at you mate but One thing I could always appreciate is that you were not like these dumb mechanics, you actually brought intelligence to your work, even if you are an A-hole sometimes. Just to add to your explanation, when you get an increased pressure drop over the top of the wing (or bottom of the spoiler) your preventing the air from packing in and above the wing (has a slower flowrate of air compared to the bottom, notice I said flowrate not velocity) the curved shape also helps with that, less material contacting the surface leads to low pressure, because pressure is A force per unit area (N/m2) and if you have less stuff contacting the top, the stuff at the bottom is going to lift, there is more of it pushing up against the flat area. Your 100% what you said, it’s a balancing act. That slower air (increased residence time... more heat transfer) will work to a point, those bonnets vents really help to draw it away and is important. Q=uA, smaller diameter pipes have a slower flowrate, higher velocity and lower pressure drop when Q is constant. Anyways people won’t understand what you are talking about but still worth sharing

[@namedisclosed1849]

Actually I might be wrong... this is not exactly like pipe flow. The top half of the wing has a larger surface area. You’re right the split air has to meet up, because it has further to travel, the larger surface area on the top is displacing a larger amount of air compared to the bottom, it creates a temporary vacuum which is quickly filled by higher velocity air... how it creates low pressure... I think at least is by frictional losses or what you like to call drag... air is more disorganised in this state and won’t pack as efficiently as laminar air and therefore you get less of it contacting the top of the wing even though there is a higher flowrate of air on the top...the bottom having more air contact will cause a higher pressure and therefore lift... i guess my point is you can’t compare it to pipeflow exactly.

[@Matty.Hill_87]

🤯🤯🤯

[@59vaughn]

But for some persistent reason nobody wants to acknowledge the Nissan delta wing....half the power, half the aero, half the weight, ....yet faster and more fuel efficient....hmmmm...🤔😎

[@Kyrazlan]

The synced particle explanation is totally wrong. The shape of the air foil compresses air at the front. The airstreams will meet back up at the chord line. Since the top curves it acts like a diffuser for that high pressure air generated at the leading edge of the wing which creates a low pressure zone because the air is being pulled against the airfoil thus creating a low pressure zone over the wing. There is also more surface area on top of the wing which creates more viscous drag which contributes to the low pressure zone being created. It has nothing to do with pairs of particles or anything. With this explanation it makes intuitive sense when you factor in angle of attack.

[@antonisp6629]

epic

[@adamcarver5599]

Why are you focusing on the airflow over the top of the car. If you want to reduce drag and increase downforce then you should be talking about the splitters and diffusers.

[@MotiveVideo]

We do. But it's also the hardest and most expensive part and least likely for our viewers to do

[@MotiveVideo]

There is also a part 2

[@Reddogg1984]

Cleetus did take Leroy to a wind tunnel, funny stuff! Real eye opener. kzbin.info/www/bejne/Z4mWZmCYfLyje7s Well done Andrew!

[@tigwelding123]

👍💪💯

[@lockjawjak]

"Dave Salloway has left the chat" (A70 supra page members will get this!)

[@drpdrp5690]

Easy. Aero is a fast Saab 🤣

[@janeblogs324]

Buy some new markers...

[@MightbeAmechanic]

Wait you were in the airforce?? Might want to do a random video and have a yarn about that and other shit you have done with your life that has gotten you to this point?

[@HHCHunterYTC]

Wait you've never seen Andrew's hektic jet tats? bruh was a steely eyed missile man

[@MightbeAmechanic]

@@HHCHunterYTC no I haven't 🤣🤣

[@Matty.Hill_87]

It makes more sense why the cars are named "jet" now

[@trustfire]

Brilliant video! Very well explained.

[@skwiz031]

Awesome Ep mate! Hangin' for Part 2!!

[@racedream86]

Great content and explain !! 👌

[@mrclown7469]

4:00 "Longer path" / "Equal Transit" theory is incorrect (which is pretty annoying if like me you were taught it, and believed it for 20+ years). If a airfoil produces force in the direction of the longest side, then planes couldn't fly upside down. See: www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html Apparently the main cause (of airfoil generated lift) is the simple Newtonian explanation of equal and opposing forces. Wing forces the air down, opposing force pushes the wing up.

[@MotiveVideo]

I'm aware of all of the lift theories. People watching this aren't aerodynamicists or engineers. Have to keep it simple. Bernoulli's principle is the key to understanding cars. The curve shapes speed air up to generate low pressure. The molecule way simplified the understanding. Three years of aerodynamics and a month with Andrew Brilliant means we know way more than our viewers can digest. We were prepared for the comments of "but this is what really happens". What we're saying isn't incorrect. It's simplified .

[@daviddroescher]

Please explain to Julian Edgar calling everything a rule of thumb/ best practices not function are total BS. It would really help out the amateur are dynamics community of ecomodder.com where is has been bashing all of our best practice development . I respect the man I think he has a lot to offer but he simply does not appear to comprehend a best practice can exist .

[@miralemnermina142]

I like him too but he always says to check does it really work by using sensors or something else. So you would know if it's wrong

[@legodude19999]

Yes! We need more aero content Andrew! Great stuff!

[@DeadTalkLive]

Good video 👍👍👍! As a fellow KZbinr, I am on the lookout for fresh ideas! Great Job!

[@biglokofourtwenty8167]

Appreciate your vids, especially gtr no secret, please more vids. Keep it up!! Subscriber here....

[@lotuselansteve]

Great video. With regard to the radiator, air only flows through them if there is a pressure differential between the faces. So, by expanding the air on the intake side, as you have done, the pressure increases as the speed drops, thereby increasing the differential pressure allowing more air to flow through thereby increasing the cooling effect.

[@Levent_Ergun]

This was like an introduction to fluid dynamics class. I have learned so much in 40 minutes, thanks Andrew.

[@manivsewparsad2511]

This is nowhere near an introduction... There is so much more knowledge you need to know before you actually can understand compressable flow

[@tommylyeah]

This is a 40 minute video? ...oh, shit, it is.

[@Levent_Ergun]

@@manivsewparsad2511 hence why I said introduction.

[@grinsomx]

Aerodynamics are beautiful.

[@iiihamzapoloiii]

Thankyou 🙏 Great video

This was great, thanks. Learned a few principles I can apply to my daily

[@OGNISTYSZKQAJDII]

what about vortex generators? i remember that cannards are kinda vortex generators