911 being rear-engined has always meant it cannot have a well-sized diffuser. They made the RSR mid-engine just to have that advantage along with better CG(just like a proper supercar would kek)
Not having the engine in the middle has never stopped the 911 from absolutely dominating every other road car on track. The fact about the lack of room for a diffuser in the race car is true though.
Because the rules didnt allowed long difusera after the bumper or something like this, so basically they had to break tradition to do that and also a better car overall since the mass is more centralized
I drove various 992.2 models at speeds of up to 340kmh and they’re incredibly stable, if anything, you get a feeling like they’re more stable the faster you go, almost as if they’re producing suction.
@@FacelessBillions Probably, but any kind of lift due to their shape (as mentioned in the video) is a non issue. Even getting airborn at 300+ due to bump(s) will not induce lift in frontal area. They do have very significant roll acceleration due to high level of lateral stiffness, and that can catch you off guard at very high speeds if you get too relaxed, but as far as aero behaviour goes, they really don’t leave much to be desired. You can cruise at 320 for very extended periods of time.
@@polipochilegge On the cars that are revealed to the public as of today, yes, correct, always with the wing up (which in that case also serves as active air ducting).
Clearly you haven't seen a 911 from the underside. The hump you tal about is exactly where the exhaust manifolds and mufflers are. It's the only part of the car that hasn't got a flat bellypan because off the heat and accessibility to the engine/ exhaust.
Your solution is partially good because you calculate it on a steady speed and assuming a constant ground clearance. In reality the ground clearance will vary depending of the circuit, road and suspension compression due to downforce. This will result in an unstable behaviour at higher speeds during a quick ground clearance change. (See Mercedes crash at Le Mans in 1999) A fixed wing will provide consistent down force at cost of drag.
Also of note is that, while this bump may be more efficient in terms of -L/D, It's important to consider the design priorities of the Porsche. Porsche, unlike many supercars, doesn't put too big of an emphasis on the top speed, instead focusing on broader handling performance. The added fuel economy penalty from the drag is also not really a concern since, well... it's a Porsche, if you can afford one you can afford the added gas prices. Overall the bump seems like it would be a good solution if this were for a cheap, slow road car that happened to be shaped similarly, like the beetle, but on the Porsche it somewhat conflicts with the actual design principles.
The same can be said of pretty much everything about the car, including the entire car itself because it is sensitive to the angle of attack. Wing lift changes with angle of attack too, so no consistent downforce or drag production.
The bump as illustrated is a fair way from the ground so while some suspension movement will vary it's effect to some degree it's unlikely to be crucial.
I remember having a conversation with people about cars, and someone mentioned that the Porsche 911 has the best aerodynamics(Their reasoning was something like, "Because it's a Porsche"). I said that wasn’t true and that the 911's is quite unstable at high speeds due to car body shape. They looked at me like I was crazy :D
I have noticed that they are very pitch sensitive, raising or lowering the front axle +/- 5-10mm brings a whole new set of dynamics at high speed vs low/medium speed as you trade mechanical grip balance for aero balance. It makes setting the cars up frustrating for the uninitiated. It is not intuitive to me how adding a bump around the diffuser improves things. Factory examples of increasing diffuser efficiency on these cars involves tilting the engine up to allow more clearance for a larger and longer diffuser.
The bump effectively removes the need for changing the engine placement. Also, the bump can be placed anywhere very easily, not just in the diffuser area. Placing it there increases the downforce for the rear wheels.
@ Recently watched top gears episode on the Manthey 992 GT3RS where the Manthey rep talks about the use of multiple curves in the diffuser to help keep the airflow attached. Is this a similar principle to what you achieve with the bump? I have been looking at ways to fit or build an improved diffuser to 991 gt3 for laptime improvement.
That person was correct. The GT cars and the rs models specifically, make better use of aero than pretty much any street legal car out there, barring any super low production unicorn or street legal race car build.
Only from driving a 992.1 i cant agree, its like there a too many things missing on the Aero Car Parts. Like the Design of the Groundplate and the Brake cooling airflow. Or the flow when the Wing is out and air is forced to go from Roof strait in the engine area and comes out between the mufflers.
It's wonderful that you have been able to teach Porsche AG something they didn't about the Aeros of their 911s !!! Maybe you can now give your advice to Lockheed Martin for their F-16 and F-35 Programs and then EDAS!
Physics is physics. It doesn't care who you are. You have a lot to learn about the automotive industry. As for the F35, it was a bit of a failed attempt, so sure, I can have a look at it.
The audi A2 would be interesting to see, iirc they went all out on aerodynamics weight and efficiency to get one of the most efficient cars at the time
I think there's something off with the model: the 992 has some small front diffusers, just before the front wheels, shouldn't those affect the underbody behave, generating more suction than like, a completely flat part?
I know that you probably have more sugested ideas than you can make in 5 lifetimes, but I just couldn't leave 2 more ideas to be forgotten without a chance of analysys. 1st one: do roof railings really add so much drag? or maybe they can in some weird way help in some cases (working like a spoiler or vortices generators) and why do some of them are so noisy 2nd one (maybe not as much with cars) how much better aerodynamics do sportbikes have over naked bikes? (easy comparason might be between MT series bikes and R series both from Yamaha, mostly same chassis and engines, but R's with and MT's without fairings) I really appreciate your work and how you make aerodynamics easier to understand for people like me (still in highschool) even though they are one of the most complex things in physics.
me and my dad are trying to build an s2000, can you please make a video on some good ways to increase aerodynamic efficiency? thank you, i learn alot from these videos
I feel like this needs to be analysed factoring in suspension. Ground clearance, balance, heave and roll characteristics... I think they went with a spoiler because its out of the way
This is interesting, but Porsche employs some very smart aerodynamicists. I have to think if this were indeed a simple way to reduce lift without a penalty, they'd do it. So I don't know what it is, but there must be a downside they've considered that isn't covered here. Reduced ground clearance perhaps? If the limiting factor is the height of the lowest point on the car, for clearance, perhaps it's better to have the whole floor at that height (aside from the diffuser), effectively making the whole floor be the 'bump'?
@@PremierAerodynamicsevery modern RS car would disagree with that statement lol. I have 2 theories why Porsche didn’t do this, and it could very well be a combination of both. 1st theory: Ground clearance. People in the comments saying the ground clearance would be negligible likely haven’t driven a 911. The rear of the car often scrapes worse than the front because of how far the body extends beyond the rear wheels and the weight of the engine in back. Many countries nowadays have regulations for ground clearance, so adding that hump may have made it so they had to raise the car, negating any positive effects on handling the bump had. 2nd theory: the GT3 and GT3RS both already have better aerodynamics and diffusers. Every upgrade they make to the base model brings it a bit closer to the top of the line model, so the manufacturer is hesitant. This happens across the whole car industry, not just Porsche.
I would highly appreciate if you could do a similar video on the 986 Boxster, it has a lift problem. Roof on and off, would be interesting to see what damage the open top does. I drive mine on track and would love some more downforce and less lift :) thanks!
That, in my opinion, is the best porsche because it was nimble and the chassis was a little flexible, so you could feel the road way more. Later models, and the 911's, feel really dead in comparison.
I mean... if somehow making the diffuser less curved and more bumped out makes things better, doesn't that just mean the diffuser is poorly designed... Also, i was wondering, doesn't this increase the frontal area of the car? Or is the bump only placed in the space created by the early sloping of the underbody of the car?
You can move the bump anywhere to help change the balance of the car too. If the bump protrudes out further than the projection of the lowest point, then it does. Otherwise, it doesn't.
Could you do an Alfa Romeo Giulia((non-QV) with a factory spoiler? Does the aero performance match the looks? I'm building a track car out of one, and would love to find out where it needs aero. Love your videos!
You missed the Effekt off the intake cooler air exausts in the back. Thex differ from Modell to modell. that changes the underpressurezone and the hole airflow in the real
I remember seeing similar solutions on the front diffuser of some LMP race cars (can't remember which one). So it's definitely an effective solution. That being said, I feel like lowering ground clearance of the entire car to the height of lowest point of the bump might create more downforce. Perhaps that's why it's rarely seen on production cars?
Hi. If you're looking for suggestions for next videos, I'd suggest analyzing Tesla Y because it's an SUV with a very low drag coefficient and thus an outlier, something where most car manufacturers could seriously improve and lower fuel consumption and aero noise if they followed the same science.
Interested in your thoughts: I have a 2018 (991.2) targa GTS, and it is extremely stable, possibly even more so, at high speeds. Given what you described in the video, the opposite should be expected, so I’m wondering why this stability occurs?
It is quite different to most 911's, despite looking quite similar. For example, the lip at the front borders on a small splitter, and that alone really helps produce downforce. You also have vents at the top of the front wheel houses, which for this particular car helps alleviate high pressure in the wheel houses, and that reduces the lift too. Also, the entire car is angled down slightly, so the entire underbody is essentially just one big diffuser.
All this talk of the 911 being unstable at speed, which generation are you guys speaking on? My 997 is rock solid rite up to 170+ where the nose does feel light if you hit a bump or big dip…. I’d imagine not many road cars are super stable at those speeds
If the porsche ground clearance would be 30cm higher lets say, would the added bump add lift to the rear? It seems that the factor that lowers overall lift value on the porsche in the video is the venturi effect, which the company used in real life but with an inflatable spoiler in the front
1. Awww come on I asked for a "Porsche is more aerodynamic in reverse" video. 2. As others have stated, the underbody is "open" there because of secondary engine cooling and the massive exhaust manifolds and catalytic converters all housed behind the rear axle, which prevents any proper diffuser design in the first place (let alone a hump). 3. Considering how far Porsche design language has come especially regarding the 911, I wonder how bad the '60-'70 classic 911 was with the upright windscreen but less frontal area overall.
Having a bump there is essentially the opposite of having a diffuser right? Because the diffuser would hollow out that space. So if the bump reduces the pressure an reduces lift, how does a diffuser do the same?
The geometry isn't really the important thing. The important thing is the gradient of the geometry. So, they both create downforce because of the acceleration of the air. The bump also has a couple extra features, like the Venturi effect, which amplifies that acceleration, and then being close to the ground also gives you more room to make an even more extreme end of the bump/diffuser.
the original center of lift was pretty central and the new diffuser creates low pressure locally and offset to the rear giving a rotational moment with increasing speed. That's an undesired effect
Are you sure it’s a good idea to use RANS and stationary wheels here? I feel like that choice would seriously hinder the validity of the results in this application
That’s good. The results look averaged though, did you do that in post? I can’t be sure but without MRFs the pressure distribution on the underside would probably be significantly different.
Placing the bump right between the wheels makes sense from a ground clearance standpoint. A little forward of the rear wheels or right between them sounds like a good position, since that will increase the rear grip without reducing front grip, but I wonder if that would reduce the diffuser's performace because of the fact that any negative pressure where flow detaches behind the bump will suck in the dirty air of the jetting vortex of the rear wheels. Conversely, placing it right behind the rear wheels will seperate the jetting vortex of the rear wheels from the underbody flow but then the diffuser has to be extremely short, and any extra downforce created behind the rear wheels makes the front grip worse too. Also if its placed between the front wheels, it would increase the flontal area since the sloping hasn't begun, but what if the ramp from the splitter was extended to the wheels to effectly be like a shallow bump?
911 being rear-engined has always meant it cannot have a well-sized diffuser. They made the RSR mid-engine just to have that advantage along with better CG(just like a proper supercar would kek)
The bump fixed that too, if you want.
Not having the engine in the middle has never stopped the 911 from absolutely dominating every other road car on track. The fact about the lack of room for a diffuser in the race car is true though.
@@jbrandon302yeah well for that price tag it's not that surprising
@@jbrandon302🎯
Because the rules didnt allowed long difusera after the bumper or something like this, so basically they had to break tradition to do that and also a better car overall since the mass is more centralized
I drove various 992.2 models at speeds of up to 340kmh and they’re incredibly stable, if anything, you get a feeling like they’re more stable the faster you go, almost as if they’re producing suction.
Maybe because they are newer and porsche has has time to fix the issues
@@FacelessBillions
Probably, but any kind of lift due to their shape (as mentioned in the video) is a non issue.
Even getting airborn at 300+ due to bump(s) will not induce lift in frontal area.
They do have very significant roll acceleration due to high level of lateral stiffness, and that can catch you off guard at very high speeds if you get too relaxed, but as far as aero behaviour goes, they really don’t leave much to be desired.
You can cruise at 320 for very extended periods of time.
That would be with the wing up, right?
@@polipochilegge
On the cars that are revealed to the public as of today, yes, correct, always with the wing up (which in that case also serves as active air ducting).
@@drazenbudis7881 aha, there is not that much frontal lift and the weight distribution kinda compensates for the rear lift
Clearly you haven't seen a 911 from the underside. The hump you tal about is exactly where the exhaust manifolds and mufflers are. It's the only part of the car that hasn't got a flat bellypan because off the heat and accessibility to the engine/ exhaust.
I was going to say the same thing. The hump is actually already there in the form of the muffler back box.
Your solution is partially good because you calculate it on a steady speed and assuming a constant ground clearance. In reality the ground clearance will vary depending of the circuit, road and suspension compression due to downforce. This will result in an unstable behaviour at higher speeds during a quick ground clearance change. (See Mercedes crash at Le Mans in 1999) A fixed wing will provide consistent down force at cost of drag.
Also of note is that, while this bump may be more efficient in terms of -L/D, It's important to consider the design priorities of the Porsche. Porsche, unlike many supercars, doesn't put too big of an emphasis on the top speed, instead focusing on broader handling performance. The added fuel economy penalty from the drag is also not really a concern since, well... it's a Porsche, if you can afford one you can afford the added gas prices. Overall the bump seems like it would be a good solution if this were for a cheap, slow road car that happened to be shaped similarly, like the beetle, but on the Porsche it somewhat conflicts with the actual design principles.
The same can be said of pretty much everything about the car, including the entire car itself because it is sensitive to the angle of attack. Wing lift changes with angle of attack too, so no consistent downforce or drag production.
The bump as illustrated is a fair way from the ground so while some suspension movement will vary it's effect to some degree it's unlikely to be crucial.
Look at 992 GT3 and 718 GT4 underside. You'll appreciate how well designed their rear diffuser and underbody are, especially on the GT3.
🎯
I remember having a conversation with people about cars, and someone mentioned that the Porsche 911 has the best aerodynamics(Their reasoning was something like, "Because it's a Porsche"). I said that wasn’t true and that the 911's is quite unstable at high speeds due to car body shape. They looked at me like I was crazy :D
I have noticed that they are very pitch sensitive, raising or lowering the front axle +/- 5-10mm brings a whole new set of dynamics at high speed vs low/medium speed as you trade mechanical grip balance for aero balance. It makes setting the cars up frustrating for the uninitiated. It is not intuitive to me how adding a bump around the diffuser improves things. Factory examples of increasing diffuser efficiency on these cars involves tilting the engine up to allow more clearance for a larger and longer diffuser.
Fanatics and logic don't mix.
The bump effectively removes the need for changing the engine placement. Also, the bump can be placed anywhere very easily, not just in the diffuser area. Placing it there increases the downforce for the rear wheels.
@ Recently watched top gears episode on the Manthey 992 GT3RS where the Manthey rep talks about the use of multiple curves in the diffuser to help keep the airflow attached. Is this a similar principle to what you achieve with the bump? I have been looking at ways to fit or build an improved diffuser to 991 gt3 for laptime improvement.
That person was correct. The GT cars and the rs models specifically, make better use of aero than pretty much any street legal car out there, barring any super low production unicorn or street legal race car build.
Please do 718 or 981 now, curious to see the differences with 911
Thanks, we'll put them on the list.
Only from driving a 992.1 i cant agree, its like there a too many things missing on the Aero Car Parts. Like the Design of the Groundplate and the Brake cooling airflow. Or the flow when the Wing is out and air is forced to go from Roof strait in the engine area and comes out between the mufflers.
It's wonderful that you have been able to teach Porsche AG something they didn't about the Aeros of their 911s !!! Maybe you can now give your advice to Lockheed Martin for their F-16 and F-35 Programs and then EDAS!
Physics is physics. It doesn't care who you are. You have a lot to learn about the automotive industry.
As for the F35, it was a bit of a failed attempt, so sure, I can have a look at it.
The audi A2 would be interesting to see, iirc they went all out on aerodynamics weight and efficiency to get one of the most efficient cars at the time
on that topic, the VW XL1 too
I think there's something off with the model: the 992 has some small front diffusers, just before the front wheels, shouldn't those affect the underbody behave, generating more suction than like, a completely flat part?
Yes sadly thats Missing
I know that you probably have more sugested ideas than you can make in 5 lifetimes, but I just couldn't leave 2 more ideas to be forgotten without a chance of analysys.
1st one:
do roof railings really add so much drag? or maybe they can in some weird way help in some cases (working like a spoiler or vortices generators) and why do some of them are so noisy
2nd one (maybe not as much with cars)
how much better aerodynamics do sportbikes have over naked bikes? (easy comparason might be between MT series bikes and R series both from Yamaha, mostly same chassis and engines, but R's with and MT's without fairings)
I really appreciate your work and how you make aerodynamics easier to understand for people like me (still in highschool) even though they are one of the most complex things in physics.
Should have done the 992 GT3 touring, I think the aero is much better
Great video tho 👍👍
Next time! We have it on the list!
me and my dad are trying to build an s2000, can you please make a video on some good ways to increase aerodynamic efficiency? thank you, i learn alot from these videos
@@aklekstobola9041
Check Julian Edgar, he has videos on youtube aswell, very understandable language and DIY solutions.
I feel like this needs to be analysed factoring in suspension. Ground clearance, balance, heave and roll characteristics... I think they went with a spoiler because its out of the way
Original Ioniq 0.24. Ioniq 6 is 0.21 drag coefficient. Just saying.
Duh it's an electric sedan
This is interesting, but Porsche employs some very smart aerodynamicists. I have to think if this were indeed a simple way to reduce lift without a penalty, they'd do it. So I don't know what it is, but there must be a downside they've considered that isn't covered here. Reduced ground clearance perhaps? If the limiting factor is the height of the lowest point on the car, for clearance, perhaps it's better to have the whole floor at that height (aside from the diffuser), effectively making the whole floor be the 'bump'?
Do you know any Porsche aerodynamicists? I do. Have you worked in the automotive industry? I have. Fundamental knowledge there is very weak.
@@PremierAerodynamicsevery modern RS car would disagree with that statement lol. I have 2 theories why Porsche didn’t do this, and it could very well be a combination of both.
1st theory: Ground clearance. People in the comments saying the ground clearance would be negligible likely haven’t driven a 911. The rear of the car often scrapes worse than the front because of how far the body extends beyond the rear wheels and the weight of the engine in back. Many countries nowadays have regulations for ground clearance, so adding that hump may have made it so they had to raise the car, negating any positive effects on handling the bump had.
2nd theory: the GT3 and GT3RS both already have better aerodynamics and diffusers. Every upgrade they make to the base model brings it a bit closer to the top of the line model, so the manufacturer is hesitant. This happens across the whole car industry, not just Porsche.
Still waiting on my 1988 lincoln town car aero test I wanna see a stock truck vs a lifted truck aerodynamics.
I would highly appreciate if you could do a similar video on the 986 Boxster, it has a lift problem. Roof on and off, would be interesting to see what damage the open top does. I drive mine on track and would love some more downforce and less lift :) thanks!
That, in my opinion, is the best porsche because it was nimble and the chassis was a little flexible, so you could feel the road way more. Later models, and the 911's, feel really dead in comparison.
@@PremierAerodynamicsyou mean flexibles as in the shocks/springs stiffness or as in chassis torsional/flex stiffness?
I mean... if somehow making the diffuser less curved and more bumped out makes things better, doesn't that just mean the diffuser is poorly designed...
Also, i was wondering, doesn't this increase the frontal area of the car? Or is the bump only placed in the space created by the early sloping of the underbody of the car?
You can move the bump anywhere to help change the balance of the car too.
If the bump protrudes out further than the projection of the lowest point, then it does. Otherwise, it doesn't.
Porsche Slant-nose vs normal-nose aerodynamics, please!
Could you do an Alfa Romeo Giulia((non-QV) with a factory spoiler? Does the aero performance match the looks? I'm building a track car out of one, and would love to find out where it needs aero. Love your videos!
You missed the Effekt off the intake cooler air exausts in the back. Thex differ from Modell to modell. that changes the underpressurezone and the hole airflow in the real
always learn so much. ty!
Thanks!
I remember seeing similar solutions on the front diffuser of some LMP race cars (can't remember which one). So it's definitely an effective solution.
That being said, I feel like lowering ground clearance of the entire car to the height of lowest point of the bump might create more downforce. Perhaps that's why it's rarely seen on production cars?
Could you please factor in the large brake ducts positioned on lower control arms fore/aft? would this change lift profiles significantly?
Hi. If you're looking for suggestions for next videos, I'd suggest analyzing Tesla Y because it's an SUV with a very low drag coefficient and thus an outlier, something where most car manufacturers could seriously improve and lower fuel consumption and aero noise if they followed the same science.
Thanks, we have it coming out in a week or two, and we're also looking at how to improve it too.
Interested in your thoughts: I have a 2018 (991.2) targa GTS, and it is extremely stable, possibly even more so, at high speeds. Given what you described in the video, the opposite should be expected, so I’m wondering why this stability occurs?
It is quite different to most 911's, despite looking quite similar. For example, the lip at the front borders on a small splitter, and that alone really helps produce downforce. You also have vents at the top of the front wheel houses, which for this particular car helps alleviate high pressure in the wheel houses, and that reduces the lift too.
Also, the entire car is angled down slightly, so the entire underbody is essentially just one big diffuser.
All this talk of the 911 being unstable at speed, which generation are you guys speaking on? My 997 is rock solid rite up to 170+ where the nose does feel light if you hit a bump or big dip…. I’d imagine not many road cars are super stable at those speeds
If the porsche ground clearance would be 30cm higher lets say, would the added bump add lift to the rear? It seems that the factor that lowers overall lift value on the porsche in the video is the venturi effect, which the company used in real life but with an inflatable spoiler in the front
The higher up you go, the less effective the venturi effect becomes.
What program are you using and what is your PC Specs/what would you recommend for CFD??
Nevermind, it’s OpenFoam!
Yep
I'm still hoping for Vauxhall VX220 NA (not turbo) aerodynamics
Thera are video's about that car... It's bad. :)
GR86 w/without ducktail next please!
can you do the mg ex181 next?
Could you make an analysis on the Ferrari Enzo?
I've always wondered how it performes, given that is has no rear spoiler.
Can you fix Aerodynamics of second gen Prius so it can travel at 650 kph?
Lol, I think next week (or the week after), we will have a Prius, but it might not be at 650 kph.
@PremierAerodynamics that's just sad to me
1. Awww come on I asked for a "Porsche is more aerodynamic in reverse" video.
2. As others have stated, the underbody is "open" there because of secondary engine cooling and the massive exhaust manifolds and catalytic converters all housed behind the rear axle, which prevents any proper diffuser design in the first place (let alone a hump).
3. Considering how far Porsche design language has come especially regarding the 911, I wonder how bad the '60-'70 classic 911 was with the upright windscreen but less frontal area overall.
Having a bump there is essentially the opposite of having a diffuser right? Because the diffuser would hollow out that space. So if the bump reduces the pressure an reduces lift, how does a diffuser do the same?
The geometry isn't really the important thing. The important thing is the gradient of the geometry. So, they both create downforce because of the acceleration of the air. The bump also has a couple extra features, like the Venturi effect, which amplifies that acceleration, and then being close to the ground also gives you more room to make an even more extreme end of the bump/diffuser.
Where did you get the geometry from? Any way to share it or tell us where you found it? Cheers!
can you make a video for ss1le? I am very interesting on how since it have very low approach angle from window how will the air attach through the top
How about a extended lip in the rear bumper?
That would help reduce the lift and the drag too.
would you plz do a Gr Supra? The normal one or the A91 CF ( have more aero) thank you.
Where do you get your models from?
Also would it not be more accurate to simulate wheel rotation, why is it not being simulated?
Can you do a video for the new mistral?
the original center of lift was pretty central and the new diffuser creates low pressure locally and offset to the rear giving a rotational moment with increasing speed. That's an undesired effect
As said in the video, you can change where the bump is, and for those who like to live dangerously, you could always have more than one.
Porsche seeing this: WRITE THAT DOWN WRITE THAT DOWN!!
Lol
Can you do one on the Porsche 911 3.3 turbo?
What software do you use to do the simulations?
OpenFOAM.
We have courses on it on our website. And we currently have a Christmas special on, if you're interested.
Thanks!
Thanks for the video!
You're welcome!
I think Ferrari did this with an inflatable sac in the splitter, but I don't remember the car.
Yeah! The inflatable sacks are cool.
inflatable sacks are tight!
dont the newer 911s have bumps under the car that pop out when needed... like legit underbody active aero
I don't know. I can't keep up with all the variants.
How can i reduce lift on my boring daily drivers
It depends on the car. One of the most effective ways is a splitter plate.
I thought the bump would mess with the wake way more.
idk how drastic the differences will be with rear spoiler deployed
There'd be a little bit because the diffuser would work a little better, but the general idea behind the bump works still.
@4:35 my stock Honda civic X is is at rank #3 btw.
That's a tradeoff for lower ground clearance innit?
The front is a lot lower than the bump
Aren't all sports cars essentially shaped like a wing?
Most are to some extent. Some more than others. For example the GTR is a little less wing like because the rear is flared up.
Are you sure it’s a good idea to use RANS and stationary wheels here? I feel like that choice would seriously hinder the validity of the results in this application
It's not RANS and the wheels are MRFs.
And how much do you think they will hinder the validity of the results?
That’s good. The results look averaged though, did you do that in post?
I can’t be sure but without MRFs the pressure distribution on the underside would probably be significantly different.
Imagine cars designed without pedestrian safety
What a world!
compare some of the race built Porsche cars gt4 gt3
Please do Mazda 3 hatchback
Old 911 cars have muffler as that bump.
Now do a G-model!
Placing the bump right between the wheels makes sense from a ground clearance standpoint.
A little forward of the rear wheels or right between them sounds like a good position, since that will increase the rear grip without reducing front grip, but I wonder if that would reduce the diffuser's performace because of the fact that any negative pressure where flow detaches behind the bump will suck in the dirty air of the jetting vortex of the rear wheels. Conversely, placing it right behind the rear wheels will seperate the jetting vortex of the rear wheels from the underbody flow but then the diffuser has to be extremely short, and any extra downforce created behind the rear wheels makes the front grip worse too.
Also if its placed between the front wheels, it would increase the flontal area since the sloping hasn't begun, but what if the ramp from the splitter was extended to the wheels to effectly be like a shallow bump?
It definitely could reduce the diffuser's effectiveness, but it would also reduce the wake size, so that may compensate for the diffuser's loss.
pitching moment
To be fair to Porsche, I don't think they want to give their car a poopy diaper at the back...
Their loss