I really don't think engineers took thousands of hours perfecting the aero on my 83 toyota starlet which looks like it has the same shape as a school computer
As I've aged I've learned that sometimes it doesn't matter if someone does something "stupid" to their own car. I don't think a single person who who installs a roof spoiler on their STI actually drives their car in a way that they would notice the performance difference, nor would they be the type to track before and after fuel economy numbers for such a modification, but they probably look back at their car while they're walking away and think "that looks cool." This is a 100% perfectly valid way to enjoy cars, equally as valid as the way you enjoy cars. I hope that over the five years since you've published this video you've become a little less judgmental about how others enjoy their hobby.
2:27 Well, aerodynamic efficiency is not always the focus of those engineers. Noise reduction, looks, safety etc. kinda impact that. For example: The Side Mirrors on my convertible are huge and draggy. But they have the effect that they prevent wind and noise in the cabin, even if the windows are down.
Do a video about hood vents. in Miata's for example, a lot of track guys are adding extractor vents in the hood at a low pressure zone on top of the hood. It's supposed to reduce engine bay temps (understandably) and also increase downforce. I would like to see what the effects of it really are.
Not everyone has a wing or spoiler. You didn't test the roof spoiler on it's own to see what it's affect would be on drag alone. Therefore your test is invalid and your obviously bias.
They can work but only to eliminate laminar flow separation across the surface behind them, not on a trailing edge. So, for example, they might work on the roof of SOME cars, not on others.
I just like the way it looks and am not racing my car... So the numbers don't necessarily bother me. It just looks so nice...I understand when the numbers matter, but aside from that... Love rocking mine.
The concept you describe makes sense on trunk spoilers but for cars like the former Sti and the Evos where they legit have a wing spoiler then it works because it pushed the air up towards the top part of the rear spoiler.. Thats why the evo came out with canards on the roof. So it may be dumb in one aspect but perfect for another.
Personally I think they look pretty cool...but you need to realise one thing....that not every person thats putting them on their cars are doing so for the sake of better aerodynamics....but for the sheer aesthetic purpose of improving the look of their car.
He doesn't need to realize that, he said if that's all you want it for, fine, but at least now you know what it's doing and how it affects your mpg's...
i wonder if rear window louvres would have a similar effect to a roof spoiler. I've got a 91 firebird that I'm modifying and I've been thing about the aerodynamics of it.
I'm, a min and 1:25 sec in and already you're painting with too broad a brush. You might want to change "Aero effectiveness" to "Downforce generated". On vehicles with steep rear window angles a roof spoiler helps the air stream break free from the back of the car and is many times more effective at reducing drag than a rear spoiler, especially a wing, and in most cases a front air dam and even under tray. Take a look at the back of an E30 M3 or MB 190E Evo II. They both have big rear wings and roof spoilers from the factory. Unless the rear wing of a car is at or above the height of the roof, it isn't doing much any way. Thank you for pointing this out at the end of the video. I'm with you on the FRS as the shape of that car is significantly different than a Civic, Skyline, BMW, Impreza, Evo, Mustang, Camaro, etc. And that spoiler is directing the air up and away rather than at the rear wing. Check out project tailwind from Texas Tech Mechanical Engineering department. Bottom line - If you have a vehicle shaped like a car, and not an egg, the combination of a properly designed roof spoiler and rear wing will yield better aero effectiveness than a rear wing alone.
It would be interesting to see how the older STI's raised roof spoiler would keep the laminar flow attached to the car. As opposed to the EVO's roof mounted vortex generators of the same era. And how they work in conjunction with the raised rear wings.
@GraysGarage could you discuss the roof spoiler on the 190e evo 2? It's at a shallower angle but seems just enough to maintain attachment for that huge rear spoiler on the car? Maybe you could discuss good vs bad roof spoilers?
What about cars with a steep rear window? RX8, MX5 with hard top, thing like that. Assuming there is no rear spoiler, would there be any benefit at all to the roof spoiler? I have never seen tests with these, but looking at them I would think air is just separating anyway like older cars with the notched rears. I'm no expert, so I figured I would ask. :D
I hear you on the roof spoiler being dumb. But vortex generators shouldnt be put into the same dumb category. They are used on airplanes because they are functional. The purpose of them on a car is to promote the continuation of air flow along the downward curve of the rear of the car to the rear spoiler. If you look at how an air foil (wing) works, you need air flowing over both surfaces to create lift (or weight in the case of an inverted foil). The vortex generator helps promote keeping that air flow from diminishing after that curve.
he's not dismissing vortex generators per se, as he isn't dismissing spoilers per se. it's the placement that is dumb. On a GT86 i guess vortex generators are no improvement, as the flow is attached anyways.
I don’t fully agree. He said ‘roof spoilers don’t work’ as in, all of them. But the 2nd generation WRX STI (2nd Facelift ) 2006’ model came with a spoiler type roof spoiler from factory... since he praises the research of OEM manufacturers.. And also about vortex generator... we all know the EVO VIII MR & IX came with them from factory (as an accessory) So some should work... not ‘all’
2:26 well the key thing missing here is that the engineers dont do that for production cars, it is always a balance of factors to get the car to fit within crateria for general use cases, its a very real possibility you could do better than the engineers did with the areo because they were not going for maximum efficiency at all costs, the car has to sell to mass markets and be cost effective to produce. Im not defending the roof wing here especially with the vehicles that are using them with a spoiler or wing but there is a place for roof spoilers and that place is on modern vehicles like a SUV where there is not a trunk lid to mount anything on.
Spoilers, are also used to direct clean airflow, down the rear window, to reduce mud and dirt, from the road from coating the rear window. Specifically the Toyota Yaris 5 door hatch.
"You think you're being cool and ya know making your car better but you're actually being stupid and making your car worse." hahahaha. Love that quote! Great video sir. I love this video! Subscribed!
Two things, sometimes i think people do it purely for aesthetics, secondly, what if it is just a hatchback and you have no other option if you still want a wing that looks relatively OEM.
I agree with your assessment of roof spoilers! I am trying to find an aerodynamic device to put on my RV. I have seen one, but I don't know what it is called! It is similar to what semi-trucks have on the cab to make it more aerodynamic.
Ummm there were a few years though subaru actually did go back to the drawling board cause the giant wing was doing crap. They added on a true roof spoiler and the aero testing was night and day.
For another episode, could you show what use do some unconventional spoilers/wings have? Personally the BMW 3.0 CSL's roof spoiler is bugging me. The one on top of the rear window, which is set in an awkward direction. Does it direct the flow to the rear wing? Doesn't it produce lift? For reference: static.carthrottle.com/workspace/uploads/posts/2015/09/654e0a03-e0d8-4432-9134-6c4f35303b1a.jpg
technically if the roof spoiler is angled downwards to reach that target angle of 12-13* you claimed, they would be beneficial no? (not like the upward angled ones you posted) ie. like the MR2 in the first video, because of the rear hatch section, if there was a roof spoiler to angle it downward I would think that would be a good combination to a trunk mounted spoiler. ...but I could be wrong....
It doesn't matter what angle the roof spoiler is at. If the air doesn't flow smoothly down the rear window area, you are making your aerodynamics worse. Even if you changed the angle, the air still won't be flowing smoothly down the rear of the vehicle. The roof spoiler will still be disturbing it. Engineers design the rear of cars with aerodynamic efficiency in mind to improve fuel economy and handling. Do you think you know more about aerodynamics than an engineer at Toyota or Honda?
@@gamewizard1760 what if i own a del sol with a raodster style rear my back window is flat leaving a big aera for air to pocket in i have a rocket bunny spoiler of an s14 and am considering buying a eg hatch spoiler and puttiung it on the back of where the targa top sits above my 3rd brake light.
How about using a roof spoiler to supplement a ducktail? Like forcing the flow to separate earlier so it doesn't hit a rather large, close to vertical ducktail spoiler?
People don't know economics. It's not just the economics of if it's worth the money for their customizing/ upgrading but more like people just don't know the difference between spending money on a "want" compared to a "need". Do they "want" a roof spoiler or do they "need" a roof spoiler.
Hi, So, I drive an 04 Honda HR-V and it has a spoiler, from factory, before the end of the car... what might it be for? It's an 90/10 FWD Mini SUV with the aesthetic of a curvy brick. I suspect that it is to stabilize the air, so , technically drag reduction, since it is virtually flat and has not angle of attack and the car it's self can go particularly fast.
the GTR notchback has a big bubble behind the windscreen...the wing would have to be higher to be in "good air" and work effectively. Give them a break. Any aero device is pretty moot under 80 kph...and it only costs $99 to look cool.
What about roof lips on sedans with factory trunk lips? (ie 9th gen Accord) My initial thought is it's purely cosmetic and there wouldn't be much effect at all on drag/lift.
Hey great info here. If you don't have a trunk or roof spoiler and don't intend to track the car but want some downforce. I have a mk4 supra with no wing and don't want to put a large wing on it as it is a street car. Would putting a well designed roof spoiler help with downforce or just leaving it without anything?
Might be a long shot, but what about a case where the roof mounted "aid" didn't try to be a "spoiler", but instead acted to help direct the flow, like a directional vane?
Mr Grays, great video as always, I just wanted to take the time to thank you for your work, also great music selection, compliments really nicely your videos!
Hey Gray, I have an SW20 and I remember from looking at your special on the MR2s that there is a dead zone with re circulation above the engine lid. I was curious the small roof lips in that situation create the same problem with the rear wing or if it serves to help clean up the rear aero a bit on the SW20's?
This guy made me not get a roof spoiler because I bought a wrx looking spoiler for my corolla at 90/100mph and didnt want it to be useless with the roof spoiler
Ironic t shirt. The upper spoiler is fitted to decrease downforce for drifting purposes to create a Smooth straight non turbulent non tumbling airflow off the rear, also for towing caravans with wagons increases airflow efficiency trailer And creates less dust from kicking up.
Hey! Great video. I really appreciate what you're doing to explore the aerodynamics of cars with small scale models. Any chance you can do a video on Vortex Generators? I'd love to see them in your tiny hydrogen bubble wind tunnel.
Lets be honest invariably every car is engineered to a price point and car dynamics that are quiet and will not get you killed, they are not really worried about how much down force you might get, maybe cowling for MPG but not much else
Hey I would like if you can suggest any aerodinamyc device to help to my Ford Ranger 2004 to get a better milleage, and of course I would like to see your water tunnel test, thanks
Watching this video after waiting a month for my Result Japan Roof Wing for my GR86, bc I wanted to find a good GT wing for actual downforce 😅. I know this is an old video but if you see my comment, please give me some advice on what kind of wing and mounting height in relation to the rood wing won't make it do more harm than good. Im now realizing that the trunk spoiler + roof spoiler + GT wing may be a bit much but I also like to actually perform well at the track so to sum up my biggest question right now. If I want to have the roof wing and trunk spoiler for the looks, and I plan to have a proper chassis mount splitter, verus underbody, and a proper chassis mount GT wing, will the non functional aero, (roof wing and trunk spoiler) hurt me or can I still make a functionally fast car with it if ai set it up right and how can i do that?
Also just for reference the result Japan roof wing doesn't have the little accent flap at the edge but it does plane out the roof line so I imagine I would need a rear wing just tall enough to crest just above the roof wings highest point? Or should I completely abort the roof wing because the drag will be far too great and ultimately ruin the cars high speed performance 😊
All too true, and I share your antipathy for roof spoilers (on three-box cars), but you've really let it get to you! One other thing though, in Ep. 1, you quoted Toyota's figure that the OEM boot spoiler reduced the drag by 3-4%, yet you've clearly since measured a drag increase on a model. Could the discrepancy be accounted for by differences between the model and full-size? The real car will surely have a lot more irregularities on its surface.
I am thinking of getting a roof spoiler since my 2017 Honda civic SI has a stock trunk spoiler/wing that is not free flowing and seems to just be an air dam. I would think this would be better than hitting the solid spoiler?
Like the video and don't have a roof spoiler. However wondering why some sedan WRC rally cars have roof spoilers, such as the mid 2005 Subaru WRC world rally cars? Granted the trunk spoiler is massive but still well underneath the roof line and in the wake of the roof spoiler. Perhaps your extreme hatred of roof spoiler is too generalized haha, might be useful in some cases?
In your 7th episode, the Gurney flap get a circulating flow closed and stabillised behind the rear window, and need a low speed flow to be efficient. Could'nt the roof spoiler help for that flow ?
Good to hear that a roof spoiler works on a hatchback. Care to make a video on aerodynamics of hatchbacks with spoilers and clean look? Much appreciated :)
GraysGarage How about experimenting with a gurney flap mounted on a hatchback with a factory rear spoiler...? My car (2011 WRX hatch) has a "spoiler" looking thing on the back, which does next to nothing... The only thing it does, apparently, is induce aerodynamic turbulence causing my rear window to get dirty. My old 2.5RS had two spoilers (high and mid) and the top spoiler kept the flow clean, keeping the rear window clean. The mid spoiler created so much turbulence, I once had thirty pounds of snow on my hatch... The rear windshield wiper stopped working. So, my query is regarding that design, and how I can make it more functional. I am considering adding a Gurney flap to the existing rear spoiler and combining that with my front lip (tests are inconclusive about the downforce it added) for both styling and downforce... And even to keep my rear window cleaner!
How about for the AW11? I was experimenting a little bit with it off vs. on but obviously couldn't tell any difference on the street. I want to add a rear wing onto it because it will soon be my dedicated track car so would it be more beneficial to remove the OEM roof spoiler/rear lip thing or just keep it?
I wonder how the roof mounted spoiler would affect an ae86 coupe. It's rear end is similar to the aw11 and that car came with a oem room spoiler but with now upward curve.
Peter Stockwell no he didn’t , unfortunately because that’s what I’m trying to find to reduce trunk related drag on my Jetta. Although engineers do extensive testing, they still incorporate aesthetics. Most people don’t like the visual of roof spoilers. But I can’t find data to back up the use of a roof spoiler on a sedan that has no rear spoiler.
@@Seajay1337 Any feedback yet? I ordered a high quality fiberglass roof spoiler for my g37s. Reason, because my trunk has no wing on it. Figured the roof wing will look nice and reduce drag.
other interesting roof add-ons I would like to see, vortex generators like some evo's have, and the wings on the back of some suv's and vans that are pointed sharply downward
Hey man, I dunno if you're still active on youtube, but I've been trying to do some basic CFD and design with my shitbox ice race car. I want to design a giant roof mounted wing to work between 20-40mph. I can't do much under the car as it's probably going to eat snow berms every now and then. Any tips? I'm just kinda winging it with an inverted airfoil using flowsquare to visualize it.
taking a wing off is much more of a pain in the ass than adding a roof spoiler with double sided tape, basically what I am getting is that roof spoilers are good when you want less downforce, let's say drag racing or top speed challenges
unfortunately the look dang cool. yeah it's probably better if the manufacturer designed the car with the spoiler in mind 2:53 I had this exact part on my Impreza lol. now, that was the only spoiler in my case
I'm curious if you would compare these results with something like the roof spoiler on the Ferrari 308. That appears like it would also channel air down toward the engine deck lid, and might make an interesting comparison of airflow.
What about the roof spoiler on the Ford RS200? it flows the air in the opposite direction (creating lift) however it sends more flow to the boot (trunk, its a car not an elephant) spoiler
And another important point, if we put exactly same spoiler in roof he made a lot less downforce than if we put in the rear, because when more rear is the spoiler, more lever efect, thats why why extreme arodinamyc cars like peaks peak, put the wings even out of the lenght car, far of the wheels, making same drag but a lot more downforce for lever effect. But put the wing in the roof is so stupid, a lot drag and low downforce.
What about roof spoilers on hatchbacks that are supposed to make them more efficient? I drive a Renault Clio 4 Econobox which has one and it is the same for the VW Polo Bluemotion which is supposed to be very efficient, more than the standard Polo models.
My sedan came with a company fitted roof spoiler but i didn't add any spoiler on the trunk. The spoiler is a straight one (like the ones that have brake lights) will it help the car's performance or should i get it removed
Good vid thanks Grey. I have a kamm back on my hatch back, it extends 650mm from the end of the roof at 12 degrees. The car is an eg civic, the sifes have a gentle radius and the back is open leaving a void. Any thoughts?
I really don't think engineers took thousands of hours perfecting the aero on my 83 toyota starlet which looks like it has the same shape as a school computer
And my fiat 131 has a roof wing in homologation car. 😅
As I've aged I've learned that sometimes it doesn't matter if someone does something "stupid" to their own car. I don't think a single person who who installs a roof spoiler on their STI actually drives their car in a way that they would notice the performance difference, nor would they be the type to track before and after fuel economy numbers for such a modification, but they probably look back at their car while they're walking away and think "that looks cool." This is a 100% perfectly valid way to enjoy cars, equally as valid as the way you enjoy cars.
I hope that over the five years since you've published this video you've become a little less judgmental about how others enjoy their hobby.
Im that person lol. I love how they look.
You never came back to vortex generators
2:27 Well, aerodynamic efficiency is not always the focus of those engineers. Noise reduction, looks, safety etc. kinda impact that.
For example: The Side Mirrors on my convertible are huge and draggy. But they have the effect that they prevent wind and noise in the cabin, even if the windows are down.
Screw you
I like my roof spoiler!
I paid a $120 for it, it looks cool.
I'm gonna run it
Jon Hurley actually I don't have a roof spoiler
in fact I don't even have a car
buf if I had one, it wouldn't have a roof spoiler
Kalimerakis don't do drugs
that does sum up the marketing of these spoilers perfectly though!
That’s right it makes you happy right.
Do a video about hood vents. in Miata's for example, a lot of track guys are adding extractor vents in the hood at a low pressure zone on top of the hood. It's supposed to reduce engine bay temps (understandably) and also increase downforce. I would like to see what the effects of it really are.
If it's got a undertray the vents would be helpful if they routed the radiator air up that way
@@barblupwrx6571 thanks for that quick reply buddy
@@Bashirbros in 5 years he will say no problem, I'm calling it
Not everyone has a wing or spoiler. You didn't test the roof spoiler on it's own to see what it's affect would be on drag alone. Therefore your test is invalid and your obviously bias.
No, he was testing the effect of adding a roof spoiler to cars that already have spoilers or wings. That was the whole point of the video.
How about the vortex generators??
They can work but only to eliminate laminar flow separation across the surface behind them, not on a trailing edge. So, for example, they might work on the roof of SOME cars, not on others.
Thank You GraysGarage! Finally, someone who puts engineering and science to use.
I just like the way it looks and am not racing my car... So the numbers don't necessarily bother me. It just looks so nice...I understand when the numbers matter, but aside from that... Love rocking mine.
The concept you describe makes sense on trunk spoilers but for cars like the former Sti and the Evos where they legit have a wing spoiler then it works because it pushed the air up towards the top part of the rear spoiler.. Thats why the evo came out with canards on the roof. So it may be dumb in one aspect but perfect for another.
Showing off your signed posters? :P
Personally I think they look pretty cool...but you need to realise one thing....that not every person thats putting them on their cars are doing so for the sake of better aerodynamics....but for the sheer aesthetic purpose of improving the look of their car.
🙌
He doesn't need to realize that, he said if that's all you want it for, fine, but at least now you know what it's doing and how it affects your mpg's...
in order to improve the look of car you need to actually improve the look. in short roof spoilers don't improve the look
LILWagonBurner
matter of opinion..
i thought he mentioned 3 or 4 times that some people do it for looks... he realises
By far my favorite episode.
i wonder if rear window louvres would have a similar effect to a roof spoiler. I've got a 91 firebird that I'm modifying and I've been thing about the aerodynamics of it.
I'm, a min and 1:25 sec in and already you're painting with too broad a brush. You might want to change "Aero effectiveness" to "Downforce generated". On vehicles with steep rear window angles a roof spoiler helps the air stream break free from the back of the car and is many times more effective at reducing drag than a rear spoiler, especially a wing, and in most cases a front air dam and even under tray. Take a look at the back of an E30 M3 or MB 190E Evo II. They both have big rear wings and roof spoilers from the factory. Unless the rear wing of a car is at or above the height of the roof, it isn't doing much any way. Thank you for pointing this out at the end of the video. I'm with you on the FRS as the shape of that car is significantly different than a Civic, Skyline, BMW, Impreza, Evo, Mustang, Camaro, etc. And that spoiler is directing the air up and away rather than at the rear wing. Check out project tailwind from Texas Tech Mechanical Engineering department. Bottom line - If you have a vehicle shaped like a car, and not an egg, the combination of a properly designed roof spoiler and rear wing will yield better aero effectiveness than a rear wing alone.
It would be interesting to see how the older STI's raised roof spoiler would keep the laminar flow attached to the car. As opposed to the EVO's roof mounted vortex generators of the same era. And how they work in conjunction with the raised rear wings.
I shared your video to help stopping rice in the 86 / twin platform. Thanks for making it. and hope you get more SUBS. GL man ^_^
@GraysGarage could you discuss the roof spoiler on the 190e evo 2? It's at a shallower angle but seems just enough to maintain attachment for that huge rear spoiler on the car? Maybe you could discuss good vs bad roof spoilers?
Roof spoiler adds +50 horsepower to my car tho..
-100 when you start accelerating,
jukijunk imma get me a double roof spoiler, maybe itll add 100hp?
I can't understand how a spoiler adds horsepower. That statement is just as crazy as this video.
and 150 kangaroo power at sufficient speed
also don't forget aftermarket part brand stickers that add some 20 squirrel power, they're important!
What about cars with a steep rear window? RX8, MX5 with hard top, thing like that. Assuming there is no rear spoiler, would there be any benefit at all to the roof spoiler? I have never seen tests with these, but looking at them I would think air is just separating anyway like older cars with the notched rears. I'm no expert, so I figured I would ask. :D
or the focus rs, with its full roof wing
I hear you on the roof spoiler being dumb. But vortex generators shouldnt be put into the same dumb category. They are used on airplanes because they are functional. The purpose of them on a car is to promote the continuation of air flow along the downward curve of the rear of the car to the rear spoiler. If you look at how an air foil (wing) works, you need air flowing over both surfaces to create lift (or weight in the case of an inverted foil). The vortex generator helps promote keeping that air flow from diminishing after that curve.
he's not dismissing vortex generators per se, as he isn't dismissing spoilers per se. it's the placement that is dumb. On a GT86 i guess vortex generators are no improvement, as the flow is attached anyways.
I don’t fully agree. He said ‘roof spoilers don’t work’ as in, all of them. But the 2nd generation WRX STI (2nd Facelift ) 2006’ model came with a spoiler type roof spoiler from factory... since he praises the research of OEM manufacturers..
And also about vortex generator... we all know the EVO VIII MR & IX came with them from factory (as an accessory)
So some should work... not ‘all’
2:26 well the key thing missing here is that the engineers dont do that for production cars, it is always a balance of factors to get the car to fit within crateria for general use cases, its a very real possibility you could do better than the engineers did with the areo because they were not going for maximum efficiency at all costs, the car has to sell to mass markets and be cost effective to produce.
Im not defending the roof wing here especially with the vehicles that are using them with a spoiler or wing but there is a place for roof spoilers and that place is on modern vehicles like a SUV where there is not a trunk lid to mount anything on.
Love your rants, We should get lit, and go rip roof spoilers off cars together some nite! LOL
good for the environment!
Spoilers, are also used to direct clean airflow, down the rear window, to reduce mud and dirt, from the road from coating the rear window.
Specifically the Toyota Yaris 5 door hatch.
Much more entertaining than previous videos while staying informative.
Makes me wanna go vandalize other people's roof spoiler.
MTC0316 glad you liked it!
MTC0316 I agree. Except it makes me want to find Gray's car and attach one. :P
Don't be a spoiler..🤣
"You think you're being cool and ya know making your car better but you're actually being stupid and making your car worse." hahahaha. Love that quote! Great video sir. I love this video! Subscribed!
its a visor. shades passengers
Two things, sometimes i think people do it purely for aesthetics, secondly, what if it is just a hatchback and you have no other option if you still want a wing that looks relatively OEM.
Exactly what I was looking for 👏🏽
I agree with your assessment of roof spoilers! I am trying to find an aerodynamic device to put on my RV. I have seen one, but I don't know what it is called! It is similar to what semi-trucks have on the cab to make it more aerodynamic.
laughed so hard liked the video went to scroll down to read comments and youtube has shop for roof spoilers just under the video
Ummm there were a few years though subaru actually did go back to the drawling board cause the giant wing was doing crap. They added on a true roof spoiler and the aero testing was night and day.
Can you make a video about splitters? One thing I'm curious about is what makes splitters with a raised center section less pitch-sensitive.
For another episode, could you show what use do some unconventional spoilers/wings have?
Personally the BMW 3.0 CSL's roof spoiler is bugging me. The one on top of the rear window, which is set in an awkward direction. Does it direct the flow to the rear wing? Doesn't it produce lift?
For reference: static.carthrottle.com/workspace/uploads/posts/2015/09/654e0a03-e0d8-4432-9134-6c4f35303b1a.jpg
technically if the roof spoiler is angled downwards to reach that target angle of 12-13* you claimed, they would be beneficial no? (not like the upward angled ones you posted)
ie. like the MR2 in the first video, because of the rear hatch section, if there was a roof spoiler to angle it downward I would think that would be a good combination to a trunk mounted spoiler. ...but I could be wrong....
It doesn't matter what angle the roof spoiler is at. If the air doesn't flow smoothly down the rear window area, you are making your aerodynamics worse. Even if you changed the angle, the air still won't be flowing smoothly down the rear of the vehicle. The roof spoiler will still be disturbing it. Engineers design the rear of cars with aerodynamic efficiency in mind to improve fuel economy and handling. Do you think you know more about aerodynamics than an engineer at Toyota or Honda?
@@gamewizard1760 what if i own a del sol with a raodster style rear my back window is flat leaving a big aera for air to pocket in i have a rocket bunny spoiler of an s14 and am considering buying a eg hatch spoiler and puttiung it on the back of where the targa top sits above my 3rd brake light.
@@deletethisaccount5269 if you put a fairing over the window it might work
How about using a roof spoiler to supplement a ducktail? Like forcing the flow to separate earlier so it doesn't hit a rather large, close to vertical ducktail spoiler?
People don't know economics. It's not just the economics of if it's worth the money for their customizing/ upgrading but more like people just don't know the difference between spending money on a "want" compared to a "need". Do they "want" a roof spoiler or do they "need" a roof spoiler.
Hi, So, I drive an 04 Honda HR-V and it has a spoiler, from factory, before the end of the car... what might it be for? It's an 90/10 FWD Mini SUV with the aesthetic of a curvy brick.
I suspect that it is to stabilize the air, so , technically drag reduction, since it is virtually flat and has not angle of attack and the car it's self can go particularly fast.
the GTR notchback has a big bubble behind the windscreen...the wing would have to be higher to be in "good air" and work effectively.
Give them a break. Any aero device is pretty moot under 80 kph...and it only costs $99 to look cool.
What about roof lips on sedans with factory trunk lips? (ie 9th gen Accord) My initial thought is it's purely cosmetic and there wouldn't be much effect at all on drag/lift.
What if you just add a roof spoiler but don't have a trunk spoiler?
Mad max had a cool roof spoiler..
I won't put one in my Mazda 3 now..
Thanks 👍..
Hey great info here. If you don't have a trunk or roof spoiler and don't intend to track the car but want some downforce. I have a mk4 supra with no wing and don't want to put a large wing on it as it is a street car. Would putting a well designed roof spoiler help with downforce or just leaving it without anything?
Might be a long shot, but what about a case where the roof mounted "aid" didn't try to be a "spoiler", but instead acted to help direct the flow, like a directional vane?
You keep the paper towels right under the chick posters too. 👍
wait so how would a roof spoiler effect a duckbill spoiler? cant find anything on that topic
Would louvers on the rear window have the same effect on the wing.
I love how honest this guy is lmfao "stupid roof spoiler" hahahaha love this guy
Mr Grays, great video as always, I just wanted to take the time to thank you for your work, also great music selection, compliments really nicely your videos!
Hey Gray, I have an SW20 and I remember from looking at your special on the MR2s that there is a dead zone with re circulation above the engine lid. I was curious the small roof lips in that situation create the same problem with the rear wing or if it serves to help clean up the rear aero a bit on the SW20's?
Yes I'd like to know as well or with like a pickup with a bed cover
I dont have a spoiler. Is it better to just put a roof spoiler without a rear spoiler? Not a big fan of spoilers so thars why I ask.
This guy made me not get a roof spoiler because I bought a wrx looking spoiler for my corolla at 90/100mph and didnt want it to be useless with the roof spoiler
It looks cool
Ironic t shirt.
The upper spoiler is fitted to decrease downforce for drifting purposes to create a Smooth straight non turbulent non tumbling airflow off the rear, also for towing caravans with wagons increases airflow efficiency trailer
And creates less dust from kicking up.
What if you have no trunk spoiler? How much drag would a small roof spoiler make?
love the vid very educational ;) you just save me money
Hey! Great video. I really appreciate what you're doing to explore the aerodynamics of cars with small scale models. Any chance you can do a video on Vortex Generators? I'd love to see them in your tiny hydrogen bubble wind tunnel.
I love this, haha. So true, many Hondas here in the UK have them (only the ones that don't know what they are doing though, not all)
My car comes stock with a roof spoiler, a 2004 Subaru WRX wagon, not sedan. Do you have any idea if bad? All wagons came with it.
Lets be honest invariably every car is engineered to a price point and car dynamics that are quiet and will not get you killed, they are not really worried about how much down force you might get, maybe cowling for MPG but not much else
Just completely shitted on my dreams. I just ordered my roof spoiler 2 days ago cuz I liked the way it looked smh
I have to go install some 12" dive canards on my CRX. Hahaha
its kinda late to ask
.
but how about subaru wrx roof spoiler? its looks facing opposite direction than the other roof spoiler
In the case of Mad Max's 1972 Ford Falcon XB GT Coupe, roof spoilers are badass.
I added one, just because I think it looks kinda cool.
Hey I would like if you can suggest any aerodinamyc device to help to my Ford Ranger 2004 to get a better milleage, and of course I would like to see your water tunnel test, thanks
So if a roof spoiler helps a hatchback, then it should help a minivan and SUV too because they don't have a trunk, right?
I disagree with the vortex generators. They use them to decrease drag and decrease stall speed. They use them in the airline industry.
Roof spoilers protect the rear passengers from the glare and heat of the sun. That's why it is there :)
Watching this video after waiting a month for my Result Japan Roof Wing for my GR86, bc I wanted to find a good GT wing for actual downforce 😅. I know this is an old video but if you see my comment, please give me some advice on what kind of wing and mounting height in relation to the rood wing won't make it do more harm than good. Im now realizing that the trunk spoiler + roof spoiler + GT wing may be a bit much but I also like to actually perform well at the track so to sum up my biggest question right now. If I want to have the roof wing and trunk spoiler for the looks, and I plan to have a proper chassis mount splitter, verus underbody, and a proper chassis mount GT wing, will the non functional aero, (roof wing and trunk spoiler) hurt me or can I still make a functionally fast car with it if ai set it up right and how can i do that?
Also just for reference the result Japan roof wing doesn't have the little accent flap at the edge but it does plane out the roof line so I imagine I would need a rear wing just tall enough to crest just above the roof wings highest point? Or should I completely abort the roof wing because the drag will be far too great and ultimately ruin the cars high speed performance 😊
Nice video, good job! Learned something new here. I also liked the frustration at 10:03! :D
All too true, and I share your antipathy for roof spoilers (on three-box cars), but you've really let it get to you! One other thing though, in Ep. 1, you quoted Toyota's figure that the OEM boot spoiler reduced the drag by 3-4%, yet you've clearly since measured a drag increase on a model. Could the discrepancy be accounted for by differences between the model and full-size? The real car will surely have a lot more irregularities on its surface.
I am thinking of getting a roof spoiler since my 2017 Honda civic SI has a stock trunk spoiler/wing that is not free flowing and seems to just be an air dam. I would think this would be better than hitting the solid spoiler?
Like the video and don't have a roof spoiler. However wondering why some sedan WRC rally cars have roof spoilers, such as the mid 2005 Subaru WRC world rally cars? Granted the trunk spoiler is massive but still well underneath the roof line and in the wake of the roof spoiler. Perhaps your extreme hatred of roof spoiler is too generalized haha, might be useful in some cases?
In your 7th episode, the Gurney flap get a circulating flow closed and stabillised behind the rear window, and need a low speed flow to be efficient. Could'nt the roof spoiler help for that flow ?
Good to hear that a roof spoiler works on a hatchback. Care to make a video on aerodynamics of hatchbacks with spoilers and clean look? Much appreciated :)
Locksley Ng Check out ep 6
GraysGarage How about experimenting with a gurney flap mounted on a hatchback with a factory rear spoiler...? My car (2011 WRX hatch) has a "spoiler" looking thing on the back, which does next to nothing... The only thing it does, apparently, is induce aerodynamic turbulence causing my rear window to get dirty. My old 2.5RS had two spoilers (high and mid) and the top spoiler kept the flow clean, keeping the rear window clean. The mid spoiler created so much turbulence, I once had thirty pounds of snow on my hatch... The rear windshield wiper stopped working.
So, my query is regarding that design, and how I can make it more functional. I am considering adding a Gurney flap to the existing rear spoiler and combining that with my front lip (tests are inconclusive about the downforce it added) for both styling and downforce... And even to keep my rear window cleaner!
good video. I long thought what you proved.
How about for the AW11? I was experimenting a little bit with it off vs. on but obviously couldn't tell any difference on the street. I want to add a rear wing onto it because it will soon be my dedicated track car so would it be more beneficial to remove the OEM roof spoiler/rear lip thing or just keep it?
I wonder how the roof mounted spoiler would affect an ae86 coupe. It's rear end is similar to the aw11 and that car came with a oem room spoiler but with now upward curve.
I may have missed it but did you test a roof spoiler without a rear spoiler.
Peter Stockwell no he didn’t , unfortunately because that’s what I’m trying to find to reduce trunk related drag on my Jetta. Although engineers do extensive testing, they still incorporate aesthetics. Most people don’t like the visual of roof spoilers. But I can’t find data to back up the use of a roof spoiler on a sedan that has no rear spoiler.
@@Seajay1337 Any feedback yet? I ordered a high quality fiberglass roof spoiler for my g37s. Reason, because my trunk has no wing on it. Figured the roof wing will look nice and reduce drag.
It’s literally just for looks. Ties serve no function, in fact they get in the way, but people still wear them.
Wouldn't roof spoilers work for something that doesn't have a fastback,more like a notchback?
Maybe I missed it, but what about a subtle "roof spoiler"/rear lip on the top of the back window with no rear spoiler?
other interesting roof add-ons I would like to see, vortex generators like some evo's have, and the wings on the back of some suv's and vans that are pointed sharply downward
Hey man, I dunno if you're still active on youtube, but I've been trying to do some basic CFD and design with my shitbox ice race car. I want to design a giant roof mounted wing to work between 20-40mph. I can't do much under the car as it's probably going to eat snow berms every now and then. Any tips? I'm just kinda winging it with an inverted airfoil using flowsquare to visualize it.
taking a wing off is much more of a pain in the ass than adding a roof spoiler with double sided tape, basically what I am getting is that roof spoilers are good when you want less downforce, let's say drag racing or top speed challenges
unfortunately the look dang cool. yeah it's probably better if the manufacturer designed the car with the spoiler in mind
2:53 I had this exact part on my Impreza lol. now, that was the only spoiler in my case
Hey could you do one for a 98 civic coupe? I'm looking to reduce my drag.
I'm curious if you would compare these results with something like the roof spoiler on the Ferrari 308. That appears like it would also channel air down toward the engine deck lid, and might make an interesting comparison of airflow.
What about the roof spoiler on the Ford RS200? it flows the air in the opposite direction (creating lift) however it sends more flow to the boot (trunk, its a car not an elephant) spoiler
And another important point, if we put exactly same spoiler in roof he made a lot less downforce than if we put in the rear, because when more rear is the spoiler, more lever efect, thats why why extreme arodinamyc cars like peaks peak, put the wings even out of the lenght car, far of the wheels, making same drag but a lot more downforce for lever effect. But put the wing in the roof is so stupid, a lot drag and low downforce.
What about roof spoilers on hatchbacks that are supposed to make them more efficient? I drive a Renault Clio 4 Econobox which has one and it is the same for the VW Polo Bluemotion which is supposed to be very efficient, more than the standard Polo models.
Are you able to show the effectiveness of the large factory aero wing on the 86? I think in your corner of the world it is called the Nurspec wing
My sedan came with a company fitted roof spoiler but i didn't add any spoiler on the trunk. The spoiler is a straight one (like the ones that have brake lights) will it help the car's performance or should i get it removed
Hi, I'd like to know if only the roof spolier is better or worse. Thanks.
I've seen cars with both a large spoiler and a ducktail, are the gains improved with that kind of set up?
What about the ones that the sti had back in 07 sedan. I think the strip on top diverts air down towards the big wing. Right? Wrong?
Good vid thanks Grey. I have a kamm back on my hatch back, it extends 650mm from the end of the roof at 12 degrees. The car is an eg civic, the sifes have a gentle radius and the back is open leaving a void. Any thoughts?