How Do Diffusers/Splitters/Undertrays Work?
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- เผยแพร่เมื่อ 28 ก.พ. 2015
- Today, we look into how undertrays, splitters and diffusers work, starting off with a simple explanation, before moving into some case studies and a discussion of underbody sealing and canards. Sorry for the epic video length, there was a lot of material, to help you out a table of contents is below:
-Why ground effect works 0:56
-Undertrays on F1 cars 4:12
-How the diffuser works 5:37
-What front splitters do 8:58
-Case studies of real world parts 10:48
-Sealing the underfloor with vortices 15:29
-Canards and the floor 18:27
Thanks for watching! Don't forget to like, comment and subscribe! - ยานยนต์และพาหนะ
Bro, I'm from the future. You can say "now" all you want. This autoplayed after watching your 2023 Ferrari video, love your channel. You're the best part of F1 launch season
Trust me, these is one of the only accurate explanations of how undertray and rear diffusers work on TH-cam, even motorsport . com and Autosport seems to get it wrong on their channels.
Thanks again for your help. My son is starting college of engineering and I spoke of you to make him feel more encouraged to face the hard studies of early mathematics and physics.
Best regards
You mentioned Air Dams. I'd love to hear more about Air Dams because most people do not have undertrays.
Ian Lagace agreed
Most modern cars do, but few have flat floors
Like dental damns but different
dude your videos are awesome. a lot of this goes straight over my head at the moment but in time i will understand a lot more of it, especially when i pick up physics again. this is the most helpful channel/video uploading platform on the internet regarding vehicle aerodynamics! i had no clue this subject was THIS huge lol. have a great day my friend!
Awesome vids! Its great to see a knowledgeable engineer separate fact from fiction on aftermarket stuff, and ways to improve aerodynamics on cars!
Kyle, please, make a video about canards!
Максим Грязнов it's kinda obvious though
The obvious (for you/me) can be wrong actually
canard is french for duck
ducks are quite common birds in many regions. they can be found near water and are quite tasty
Yes please!
stick man having a BLAST in a banana mobile! great vids! keep up the good work!
Your videos are just so informative and cool! How did I not find your videos earlier!
if u add some animations, it would be much better..
btw, nice explanation..
Very infomative video (Y)
Could you explain the center of pressure - center of gravity correlation a bit more in depth?
How would one notice an inbalance?
Tank you :)
Do you know the jaw of a airplane works?
the best aerodynamics channel on youtube
Your explanations are like crack for me!
They are so encouraging!
thanks so much. you're now my go to guy for all things areo!!!
Love listening to your videos, Kyle. Very good work!
There is something I don't understand and I hope you could explain it to me. How diffusers make downforce? Fast air under the car is low pressure so the pressure difference makes downforce. That make sense. But diffuser slows down the air flow and as you say, slower the air higher the pressure. So how can diffuser make downforce, if the pressure is rising there?
I was allways sure, that only purpose of diffuser is to actually just expand-diffuse fast, low pressure air under the car, slow it down and make it the higher pressure to fill the low pressure space behind the car to reduce drag and turbolences.
Well, english is not my every day language, so I hope you understand my question.
Thank you and keep good work.
Now I can show off my knowledge of what I learnt from this channel to my friends :p
Splendid video as always mate.
Back in your home (kind of) turf 😉 Great work as always!! Friend just told me about your channel and have been binging, keep up the great work mate!
Y250 vortex spin direction to seal the floor is beautiful!
thanks for all the info man I build n do radio control speed runs so this helped me learn more bout aerodynamics
I have discovered your channel this week, I like this simple aproach to aerodynamics but, could you explain better the losses of these in road cars, considering soft suspension and low speeds. thanks
Wow! That's the explanation I wanted to hear!
I understood that talking about downforce, a undertray won't help a street car. But it can improve drag coefficient?
Love your content
I am interested into listing you speak about canards. Really do enjoy listing you speak about air pressure and it helps me make better choices for my car since I am looking into doing TimeAttack.
Nazcar. Love it.
But in all seriousness, you make me want to play with a wind tunnel and learn how different shapes and combinations affect the air.
Amazing diagram
Great video !
14:35 That diffuser seems to be a huge-ass NACA duct.
Very interesting video ;) (and the audio quality is better too !)
good explanations
I couldn’t see your pictures well, but I enjoyed your video. I’d like to see a lot more pictures of aero and then why it is or isn’t effective. And I like drawings like when you illustrate which way the air spins off of a certain part 👍🏾
Awesome stuff :)
Hey...awesome video....please explain kers in details in context with F1
Love your videos dude, some very good info through them.Watching this one I want to ask you, what is the right place to put your canards? I own an early mitsubishi evo which i am trying to finish and running for time attack, and i am really interesting about aero. Now, a lot of TA cars i ve seen with extreme aerodynamics , prepared by Andrew Brilliant, have their main canards really high on the front of the car. Can you understand why he use them that way? Also a video with some more explanation about canards will be very interesting.Thanks
This is a tough one to answer. The best answer is trade off. The higher you put the canard on your bumper, the more it deflects air over the wheel wells, the lower you put the canard, the more it deflects air around the wheel well. Also, if you run a front splitter you could run into some interference issues depending. The best thing to do is consult with a professional and run simulations but that could cost mega bucks, or you can do it the old fashioned street way and ask people who have canards how and why they placed them where they are. Another thing I would look into is copying placements of time attack cars because chances are they have done the research for you, however their placements will be unique to their vehicle. The thing to remember is that Aero parts all work together in a system and no one modification will work independently from the other. They all must work together as a cohesive system to achieve the best result. Lengthy answer I hope it helps and good luck!
Don't listen to the haters!
Can you design an aero pack for my time attack car?
A book I have on racecar aerodynamics mentioned dive plates sealing the underbody. I guess I'll have to reconsider that if I ever build a racecar. :)
Thanks for these videos, much intresting information. Now i'm left wondering if making a diffuser on my own car has any benefit (non sealed floor, rules do not allow). But i do need to do something about the huge vortex behind the car ...
Thanks for sharing ! Could you explain me "Why does a flow accelerate through a curvature ?"
Hi there Kyle, I really love your videos on engineering and learned quite alot just off of them. But then again I'm sure there are much more details that goes into every area you go into. I was hoping I can trouble you to make a video on cold air intakes. I recently had a debate with my shop foreman at the dodge dealership I work at. We have a challenger that has a shaker hood that directs air from the outside and into the intake system. He claims it gives the car 30 more horsepower but I'm against his claim because that number seems very unrealistic. Hopefully you can bust the myth about cold air intakes. Great job on all your videos. Cheers!
I'm not sure I could do a whole video on CAIs, MCM I believe has done quite an in depth testing video on them that you may want to check out though. If it's an NA challenger I definitely would not believe 30 horse, if it's the supercharged one it would be higher but still I doubt 30 horse (FI cars benefit from cold air than NA). He could be trying to justify based off the ram air effect, which can often give you 1-3% power increases, however there is no way to quantitatively measure this as you will never achieve proper ram effect on a dyno. 15-20hp seems more on the money to me, unless the stock intake is terribly designed, in which case you will see significant gains. If you are still interested, I can make a video, but it will be quite some time before I clear my backlog of requests (I have about 6 videos that have been requested of me...)
Thanks for watching!
I'd love to see a video about canards, but i didn't find one on your channel.
On dive planes: Is it not that the dive plane creates alternative motion to straight flow, therefore air is less likely to go under the car if its already in a vortex than if its in a straight high pressure flow? You see these thing in use way too often in racing to dismiss their usefulness?
Wow. Great video! Wished I had seen it a loooong time ago. In the end if the vortices are in effect “closing off the sides of the floor” why not have ground effects and say bugger to wings?
Good video, audio is great. I would like to see a video on canards.
Great Video! can you explain what are the differences between a venturi tunnel and a diffuser? with is better? Thank you!
Thumbs up for that happy lil man riding in the banana car.
Wow, mind blown
Hey Kyle. Do you have any advice regarding installing an undertray onto a AWD car specifically an evo. in particular im worried about wether it could lead to overheating of the rear diff and transfer case. do you have to consider heat being trapped ontop of the under tray or is there enough airflow through here from the bumper region to not have to worry about this? also do you recommend leaving the exhaust outside of the undertray or is it okay to enclose this also.
Can you do a video about sealing off the undertray or ground effects using vortex generators?
I'd really want to see this as well. Would i be beneficial without a flat undertray? First 1/4th of my car is flat, the rest is not due to the cooling complications.
Good video Kyle. Can you answer one question for me? What is the optimum angle for a rear diffuser?
I understand not enough curve means not enough pressure. Too much angle means separation and the creation of a low pressure bubble. I seem to find that the belief is 12 - 15 degrees is best. Is that your finding?
I'm creating a diffuser for the rear of my track car and it can be anything I want it to be so inquiring minds want to know what you have found to be optimum. Thanks!
Great videos. Keep them up.
Blown diffusers in F1... is the idea behind this is to use the exhaust gas to create a vortex around the sides of the diffuser to act as a pressure barrier to increase the effectiveness of the diffuser? How does this exhaust gas create enough energy to create a barrier?
Blown DIffs don't create barriers around the diffuser, they enhance the effect of the diffuser by speeding up the air that flows through the diffuser. Exhaust gasses are typically hotter than the air moving under the car, this means when the exhaust is blown into the diffuser, the transfer of heat speeds up the air and creates a bigger suction effect. this is done by positioning the exhaust just before the position of the rear diffuser on the car. Only downside is when you accelerate, downforce increases improving handling, but when you let off the throttle, downforce weakens which decreases handling ability and causes an "on/off" effect.
Hey Kyle, how do you design a fronlt spltter/undertray that directs air away from the front tyre on a production car?
Concerning the high positioned canard vortex would it also generate a counter rotating flow vortex sealing of the side of the car with the middle of the two symmetric counter revolving flows being at the level of the front wheel?
Really nice video kyle! Very clear and well explained! I really learnt something amd would love to see a video on those trimming devices!
I have a question: you said F1 cars have that high front section because it's the best they can do with the rules and is not the ideal. So my question is what is the ideal shape for the front section of a car? Especially single seaters or open wheel racers
Cheers :)
Thanks for the compliments!
Ideally, single seaters would have a front wing (easier to tune the aero balance with an adjustable wing then just an intense undertray, plus allows you to use the areas in front of the front tyres quite well) then an open mouthed undertray. To give you an idea of what this setup would look like, check out the Monash Motorsport FSAE car, which probably has the highest downforce/size/weight ratio of any car in existence...
www.racecar-engineering.com/cars/monash/
This car also has a super awesome double element DRS system (you can see it in action right at the end of my GT86 Touring video)/ Note the diffuser exit is still larger than the inlet, this is because you get losses under the car so need to balance the pressures correctly. Also if you had an absolutely huge inlet it would be quite draggy. One thing to note here is that their inlet is operating in the wake of the front wing, they obviously have found that this compromise is worth it to ensure a large front wing that can kick the air over the tyres, however I would think if you could use a flatter area in the centre of the wing to duct the undertray inlet from it would be better. Also, it would mean you could run the floor for a longer distance forward on the car, which is something that F1 teams don't get to do.
Perhaps what should also be noted is that if the rules were unrestricted, you would have cars running sliding side skirts (as in sliding on the ground) and fairings for the wheels, both of which would help with the utillisation of the undertray.
Hope that helps and thanks for watching!
KYLE.DRIVES I think that Brabham BT46B 'Fan Car' had highest downforce produced by any racing car ever. It could create more downforce standing still than most F1 cars could at full speed. Niki Lauda's in autobiography 'To hell and back' he wrote that after a backmarker had spilled oil on the track all other cars had to slow down, 'while the brabham simply accelerated through the affected area'.
Basically that how would F1 cars could look if there is no regulations.
Hi Kyle just wanted to know if you could do a more in depth vid on the front diffuser.
Cheers
2:50 can't lie I laughed when the wing became a car 🤣 it's the fantasy of every ricer driving a giant wing
Thanks for all your vids. I don't see anything about hatchback airflows at all around on TH-cam. I drive a suzuki swift sport (zc31s) and would like to know a few stuffs. I usually run at vmax of 205kmh.
1. As I use a TM SQUARE vented Fender, should I take out the wheel arch liners ? Will it increase stability/ downforce since the air can exit from the vents? Or should I just keep the wheel arch liners on so that it can help with the cooling of the engine compartment.
2. I am still on stock suspensions and I have added a GREDDY FRONT LIP. The ground clearance is about 12cm. I am getting a front undertray soon.
3.Do I need to get the undertray throughout the length of the body or the front part is enough?
4.And is that height still too tall or just nice for any downforce?
5.Does sideskirts that protrude out do anything at that height?
6.Do I need a voltex generator before my spoiler? I am getting a PROJECT S ADJUSTABLE SPOILER.
7. Any tips for more high speed stability or more downforce for hatchback cars?
Thank you very much for all your infos.
1. If the wheel arch liner is blocking air from escaping through your vented fender, then yes. The top of the tyre has a high pressure region and you want to vent as much air from here as possible to prevent lift on the body
3. If you are looking to reduce drag or have a platform to improve downforce on, definitely go for a full body undertray
4. Your ride height is fine for low drag. If you want to make big downforce, you will have to lower it substantially, this may not be acceptable if it is a road car though.
5. At 12cm ground clearance? Doubt it.
6. On a hatchback, you won't need vgs for a spoiler/wing. If you do, it means your spoiler is in the wrong place.
7. Copy this: carsforhope.com.au/wp-content/uploads/2014/10/AMP_Charade_WTAC.jpg
Thanks for watching!
Hi Kyle. With the issue of flow separation due to the steep angle of the diffuser, could this not be solved the same way as on a steep wing by using a multi element? Or would the ground effect have some sort of a negative effect in this case?
yes they have double diffusers etc
1:30 One way to think of this is that you know the air is not going through the surface of the ground then recognize that if you had a mirror image of the wing pushing from the other direction you would get the flat line that we see as ground where the air does not penetrate. Ground effect is in essence a mirror of the lift generated by your surface.
Kile, I've been loving you channel! I wonder if you know a channel that teaches acoustics as you teach aerodynamics. I'd appreciate it if you could lead me at this direction. Thank you for your very good work and sorry for the off topic comment! Cheers!
You talked about not venting to the tires, then would it make sense to channel that air to the center like in a V shape? Or maybe out to the atmosphere, idk?
You should do an analysis of the Lamborghini Aventador SVJ. I was looking at it and they have some weird air diverters underneath. They don't seems to be placed for tire squirt diversion so I'm not sure if they help seal the underbody or what. And their diffuser seems waaay too steep to do much of anything but has holes for air to enter into the hollow strakes (not sure where it goes though). Wondering if any of it actually has a purpose worth the price point of their cars
Is there an effective ride height to ensure an optimal air flow under the vehicle for a street/track car?
Hey. You talk about wanting to shift the CD forward? why do you want to shift the aerodynamic balance forward? Shurely to much would result in a twitchy car in high downforce situations?
Tnx bro i would like to know about tubow charger installation
Also, would it be effective to put vg’s on a flat floor to help the flow stay attached to the diffuser?
Hi Kyle. In terms of front splitter isn't less air under the car better, rather than trying to ram more air under the car to gain airspeed? If you have less air under the car isnt that more of a vacuum as you have all the air on top of the car creating a large pressure differential?
One other thing is I have made some very mild aero for my street car which see's the track pretty often. Everything is made out of flat ply composite, and my diffuser entry is sealed against the car as much as possible so as to stop air from trying to get ontop of it, from there it's flat and raised at a 10-15 degree angle (raked) as it exits the back of the car, I have some vortex/air barriers along it at the edges, around the exhaust and a couple of channels as we approach the center (lowest part is 110mm from the ground, as its a high sitting street car). From watching lots of your video's recently it appears that this is less than ideal and not very effective. Tho coupled with a front splitter with a very mild 40mm protrusion and continuing flat under the car until the sump I have definitive increases in corner speeds and lap times. I have removed and reinstalled for testing purposes.
Stability is the main thing that was noticed around corner speeds of 150km/h+ where the car was previously a bit floaty, it is now planted allowing me to hold full throttle through these bends, raising my corner speed on those high speeds, as well as low speed corners down to 40km/h where I have seen 10% speed increases. My top speed on the straights were actually improved, possibly due to last corner exit speed but I feel like drag has been reduced. I have knocked 4 seconds off my previous 1 minute 16 lap time down to 1 min 12sec consistently. Once removed my fastest time was back up to 1.159 barely creating a pb for that non aero based setup. Once reinstalled i was back to running 1.12's.
Now to me this is a drastic improvement and I'm so happy i took the time to think about how air would enter and what I wanted it to do (mainly stay smooth and flat) but not at all to the extent of your videos. So what i'm wondering is, is this a surprising improvement to yourself, have I accidentally done something very right when it probably shouldn't have made much of a difference? Or is this what you would expect and basic aero still yeilds great results? because I plan to do it to another track car I currently own and id like this one to be a higher level of improvement. Or should I stick with what I have done and work from those results?
Thanks in advance
love your videos. I am however still confused how an a wing on an aircraft close to the ground will encounter a “cushion of air” but then squeezing air under under a car sucks it down
This is the first of your videos that I have watched. I found it while looking at how to make my own front splitter. All of your videos are very informative as I have spent a good majority of my afternoon watching the ones from your channel that appealed to me the most. Great job and I hope to see a lot more of these, as aerodynamics is one of the few things about cars that I don't understand very well. Very helpful.
I would like to see a video on how to make a splitter or custom undertray for a car. Specifically, I drive an ap2 s2000. What do you think of these and how can I make an undertray that will be the most effective?
Charlie Simon Thanks for the compliments! I'm not sure how I would go about do a video on that, as every car is different and unique, and often the design of your underbody is dependent on what's going on on top of it. My main tips would be keep it smooth and flat through the centre, and make sure you have a decent path for the air in and out. Also see what you can do about managing the tyre wakes, particularly the rear.
Looking for a video on how to seal the underside with smaller vortex generators and the best placement for these ( edges of diffuser... behind the front wheels wells...?) for road going cars that can't have side skirts with low clearance.... also... what about vortex generators underneath the car to seal off areas for cars that don't have full undertrays....?
I have the same question. How do you control the size and directional spin of a side mounted vortex generator meant to seal the sides?
the audio is 10 times better and its now easier to follow your ...lecture
Great! Would like to study aerodynamics myself :)
Would you do a video on ideal track width vs wheel base?
can u explain how center of pressure and center of gravity relates and how they stabilize the car ?
Kyle isn´t those flows going to the front tires useful for refrigerate the brakes (S15 pic)?
Regarding the diffuser shape at 13:16, since your time in Mercedes would it be possible to revisit this concept with maybe some more information on how it works?
Is the center of pressure just the same thing as the center of lift? (obviously upside-down for a car)
great
is it possible a specific video about valkyrie or valhalla?
How does Newey angle the front wing struts to generate reverse vortex at the Y250 to seal the sides of the floor? Thanks, enjoy ur videos . I think there should be a good opportunity for ur design career at the Pikes Peak Hill Climb. Almost no rules in the top class.
the vortex of LOW PRESSURE stops air entering the undercarriage
have u played any racing sims? Wondered what u thought about in sim setups.
Question: many American cars from the 1960's had gorgeous lines to them but these rectangular boxes on wheels had extremely poor aerodynamics and the gas milage reflects it.without a complete redesign and huge rounding off of each edge if just one reasonable modification could be done what would you suggest for a Ford like a Falcon, Galaxie or Fairlane?
Thanks so much.
Hi Kyle, You mentioned the weird rear defuser of some F1 cars that you may or may not understand (low pressure pocket). Can the reverse of be used in front of the car to 'catch' more air underneath it?
It may be possible, however the geometry would need to be much more aggressive to produce some sort of recirculation zone without forcing flow to interfere with and potentially choke the inlet. This is due to the fact that the pressure gradient is favourable instead of adverse, so separation is unlikely to occur (see my video on vortex generators). I don't think this geometry would give any benefit on the front, perhaps an S-duct or a open ramp inlet would do a much better job. I imagine that one of the reasons they may use it on the rear is to mimic a longer diffuser rake while trying to step it up in a short distance to clear driveshafts, control arms and such.
Thanks for watching!
KYLE.DRIVES Thank for the reply.
wow how did you draw that car left handed? :) what is the ideal underbody shape?
Hi.... interesting. ... early in the video u mentioned briefly about a car with a total wing profile when viewed from the side elevation. ..
If we overlook packaging of engine gesrbox n driver. . Would this produce more downforce than flat floot n diffuser.... in other words use a central section span. say a Metre wide n maybe length of say 3 to 4 metre long in wing section of s high lift NACA design inverted.... i hv a design in mind for a race car for a class which sllows a open wheeler of free design...
Also if a race car has huge downforce then is it really necessary to hv any or minimal suspension movement. . It would be on bump stops most of the time n it would ne easier to control the ride height n subsequent amount of downforce?
As u can tell.. i am just a backyard racer with limited aero knowledge. .. thx for reading this n any comments. .
Maybe a video on aero for a race car where there is free design.. eg for pikes peak or similar. ..
Thx kev.
kevin wood Check out the 80s wing F1 cars or Group C cars which have curved undertray surfaces. Their downforce production is super sensitive to ground clearance and thus is very unsafe as long as you meet bumps or roll/pitch. However Valkyrie has a relatively large ground clearance and is developed based on road conditions. In this case a flat underbody would not be effective and you have to use a curved surface to produce downforce
aston martin valrkye has a curved under body
How about a vortex generator placed at the very front of the side skirt of a car, behind the front wheel, but on the underside of the side skirt, so it would be upside down? That could create a vortex running along the length of the underside of the side sill/skirt and prevent air from escaping from the floor.
Would a front splitter that’s very low to the ground reduce the effect of the undertrays like in hillclimb monsters?
Only thing he didn't mention or comprehend about the brz is that the dimpled texter of the diffuser allows a much shaper angle with attached flow not say that it can actually fix that problem but it improves it.
Hey Kyle, thanks for the videos. I was wondering if you could demonstrate the air flow on a sprint car and areas to improve downforce. Thanks in advance!
sooo basically the diffusor itself (the part behind the rear axle) does not create downforce but is there to reduce drag and the downforce is actually created by the raked flat undertray and peaks right befor the diffusor starts (ground effect). is that correct? because I never understood how the diffusor could create downforce when there is a HIGH pressure area underneath it
The greater the pressure difference, the greater the downforce.
+Obstsalat95 i dont understand this either, i get the drag part but how does it create downforce
Well, it does not always produce downforce. As you said, reducing drag is its biggest role. But just imagine a wing. A wing would also be rounded up at the end to keep the airflow smooth and attached and not causing massive seperation which causes massive drag.
But as explained in the video, if airflow stays attached at the diffusers surface it will travel on a curve. With the flow beeing constant this means it has to go higher speed (because the way is longer) and therefore beeing at low pressure. Which would create downforce.
the air is accelerated at the diffuser, hence lower air pressure, sucking the car down
It isn't. The diffusor itself creates a high pressure / low speed area. Air is only accelerated at the small point where the angle of the diffusor starts to increase, see the comment above. Everywhere behind that point it is slowed down.
canards and front splitters are used for looks, In my opinion....I seen homemade ones break” On the freeway” If you live in Orlando, there’s no need to buy these” Plenty of material laying on the side of the highway.
I seen people mount these things backwards! I only ask one thing” For anyone making a DIY splitter” Use the right material!
Ok so I have a c5 corvette. Doing the aero mod bit right. Well I have an air dam for cooling. But the c5 has a pretty flat under body. What is that doing to the air and is it making a defuser useless my dirtying the air.
They work but what is the percentage of improvement in less drag and more down force.
Say Now as much as you want. You are doing a great job. lol, P.S. A small boom mike will work great as your lapel mic is getting clicked by your movement.
Hi. I have been getting very mixed facts about how airfoils work. So can someone please say once for all if it is because one side of the airfoil is longer thus having higher velocity then lower pressure, or because the shape creates a vacum. Thanks
draw the line a bit higher from the canards... you will see the vortex will put air towards the back of the cabin between rear wing and rear window for more rear wing efficiency
Is it only for downforce? Or does it aid in speed?
So if you wanted to drag race or simply go faster in a straight line would it help or just slow you down a bit?
Ric Rac If you were just looking to go in a straight line, a flat floor will improve your drag, but it would be best to raise the ground clearance so there is no induced drag. You also wouldn't use any type of splitter and would instead try to make the car look like an uncambered wing if you looked at if from the side, which would involve kicking up the floor at the back like a diffuser to some extent.
Thanks for watching!
2:47 "Discussing the aerodynamics of The Oscar-Meyer Weiner-mobile."
18.10 i thought of that one day when i was sleeping but i thought no one had thought of that yet
Gtr r35 vents to the wheel well for break cooling, it's still not enough though.
Porsche 911-based race cars don't have large diffusers like other race cars - no doubt because there is an engine located in that space. So, how are they competitive with the big-diffuser cars? (I suspect they have been granted a lower minimum weight)
oh oh oh, sounds like the separation pocket on that weird angle difuser is supposed to create a variable angle