How will a wing effect my 4 door front wheel drive honda at 80 mph?

what will the effect of a wing do for my 92 honda accord 4door FWD? What is the benefit of rear downforce on my car? Anyone care to explain? Thanks

9

Probably none. Espcially with a none functional wing. The wings on alot of cars are there to look good. They serve no purpose other than drag.

C

first, thanks for the reply.

there must be some functionality because the Realtime Integra (SVWC-Speedvision World Class) uses a wing. I asked a friend who is a AutoX Solo driver and he said...



""Depends on the wing.

I'm not an expert by any means on aerodynamics. But, with a properly
designed
wing setup you can lower the coefficient of drag and increase down
force where
you need it. More downforce in the back will make the vehicle more
stable at
high speeds and will help reduce some of the "dancing" that most cars
using
high rear spring rates have under braking."


any more thoughts?

At 80 MPH, it will get a thumbs up from people with a wing, a laugh from those without it. At that slow of a speed, a wing will do nothing but slow you down. If you decide to hit some higher speeds (better make sure your tires can handle it) find a wing that was designed for that car from the manufacturer. They do a lot of aerodynamics testing for a reason.

BTW, I have cruised around 90-100 in a '59 bug, no problems. I would hope a modern car could do better.

Originally posted by Sidewalk
At 80 MPH, it will get a thumbs up from people with a wing, a laugh from those without it. At that slow of a speed, a wing will do nothing but slow you down. If you decide to hit some higher speeds (better make sure your tires can handle it) find a wing that was designed for that car from the manufacturer. They do a lot of aerodynamics testing for a reason.

BTW, I have cruised around 90-100 in a '59 bug, no problems. I would hope a modern car could do better.

I can tell you are proud of that 90 mph in the Bug, so congrats. NO I certainly do not have any problems travelling up to 115 when the governor kicks in. But back to aerodynamics, at 80, there is definately some downforce to be applied. Have you ever seen the active aero on a Porche or a VR-4? It activates at 35-40 mph, yes that's right. At 80 mph you can get ALLOT of downforce.

So back to the technical question, what effect will a wing have at 80 mph on a FWD sedan?

PS I have 205/40/17 Toyo Proxes T1S's, ULTRA high performance, traction AA so yes they can handle ANYTHING my car can...

You do NOT want rear downforce on a car with FWD. That is the last thing you want. If you want to get a wing find one that will not affect the aerodynamics of your car. A wing has no use on your car. It is purly cosmetic.

Originally posted by NineTwoAccord


I can tell you are proud of that 90 mph in the Bug, so congrats. 90? That's nothing to brag about, and I don't. That was a nice little cruise, barely touching the throttle. I am affraid of what she can do.

You can't produce down force with out creating an at least equal ammount (more in reality) of drag with a wing. One of those damn conservation, "you can't get something for nothing", laws the man is always hasseling us with. :)

The effects? Somewhat worse gas milage, slower top speed, slower 1/4 time and trap speed, and 80% of people will laugh at you. Advantages: 5% of people will think you are cool (the other 15% still don't give a damn). If you happen to be on a high speed road course you may some advantage in the turns. Most auto-xs are too slow to make any difference especially in a car that's nose heavy and prone to understeer.

Originally posted by Someguy
You can't produce down force with out creating an at least equal ammount (more in reality) of drag with a wing. One of those damn conservation, "you can't get something for nothing", laws the man is always hasseling us with. :)

The effects? Somewhat worse gas milage, slower top speed, slower 1/4 time and trap speed, and 80% of people will laugh at you. Advantages: 5% of people will think you are cool (the other 15% still don't give a damn). If you happen to be on a high speed road course you may some advantage in the turns. Most auto-xs are too slow to make any difference especially in a car that's nose heavy and prone to understeer.

Thanks for the reply, that falls more in line with the Realtime ITR. They are obviously at high speeds on a road course.

If I'm asking this question in a TECHNICAL forum, I am not trying to mount a wing to look cool. Sometimes people just need to ease off of all the import mod bashing and see that there are true car enthusiasts on both sides of the road.

Originally posted by Someguy
You can't produce down force with out creating an at least equal ammount (more in reality) of drag with a wing.

I have to disagree - it is not uncommon for a long narrow wing to have a lift-over-drag ratio of 10 or more. That's not typical of what you'd find on a car, but it does show that there's not a fundamental law saying drag=>lift. In fact, it's my understanding that gliders have L/D closer to 20. (as do some high-performance aircraft, operating at certain altitudes)

Furthermore, I'd like to point out that (contrary to popular belief, even amongst automotive engineers) a properly designed & placed "spoiler" can actually reduce the wake area, and thus drag, of a vehicle. Usually this type of spoiler manifests itself as a slight overextension of the trailing edge of the trunk deck, not a protrusion from the top of the trunk. It's worth noting that the 2003 Civic hybrid will have such a spoiler. From a recent article about the civ hybrid:

"Aerodynamic enhancements include a refined front bumper, engine under cover, rear floor side under covers and a trunk spoiler."

"A rear spoiler has been added to reduce turbulence behind the vehicle."

here's a link to a pic of the tail-end of that civic hybrid, showing the "spoiler:"

http://a332.g.akamai.net/f/332/936/12h/www.edmunds.com/media/roadtests/firstdrive/2003/03.honda.civic.hybrid/honda.civichybrid.r34.500.jpg

Yeah you're right. Not sure what I was thinking. :)

Originally posted by Polygon
You do NOT want rear downforce on a car with FWD. That is the last thing you want. If you want to get a wing find one that will not affect the aerodynamics of your car. A wing has no use on your car. It is purly cosmetic.

Of course we want downforce on the rear end of a front wheel drive car, without downforce the rear of the car will "fly" on there would be no grip on the rear tires. Look at BTCC touring cars, most of them are fwd and they have wings.

I considered responding to that myself, but decided against it because (in my opinion) the assumptions behind the statement seem to be:

* the car is front-heavy, and highly susceptible to understeer (push)
* adding the wing (if it really works) will increase this tendency

OR

* the car will be raced in a straight line only
* increasing the load on the rear wheels will not help traction at the front

The first set of assumptions seem fair enough for a conservatively driven, barely modified vehicle, which I'm guessing is what we're talking about. The second set seem a bit fishy to me, but I didn't think them worth bringing up.

Obviously there are configurations and/or driving conditions that will make the wing more useful, especially the heavy braking scenario that was already mentioned.

In summary, I too disagree with the statement that there is no possible benefit to increasing downforce on the rear wheels of a FWD car. I would agree with something more like "there is not much benefit to increasing downforce on the rear wheels of a FWD car that is driven conservatively on the highway/streets"

The only time we doesn't need a rear wing on a fwd car is during acceleration.

Take a look on the wing on this car, it's a fwd racecar, the wing is built by TWR and is in carbonfibre.
http://www.flash.nu/pressbilder/mantorp/3race.jpg
http://www.flash.nu/pressbilder/jyllandsringen/6race.jpg

that's not a very precise statement, is it? Aren't there plenty of fwd cars that drive just fine with no rear wing?

If you look the car is also running a very low front splitter, which will increase the downforce on the front, and being that it is a full blown race car its probably a pretty safe asumption that its weight and weight distribution have been changed significantly from its street car form.

A wing on a FWD car does nothing at all. Its only for the looks. A better upgrade would be to stiffen your rear springs so you have less weight transfer. It increases your acceleration and it doesn't change the look of the car.

Thanks to everyone for the response, this is the type of information I am trying to get.

I have always been under the assumption that at high speeds, the trunk will actually raise UP due to high pressure over the trunk and low pressure under the trunk. Is this true?

I do start to feel just a bit "loose" or "squirly" at high speed 80+, nothing serious but say I pass a semi at 80+ I can tell the rear will lean to one side or the other.

I am not trying to get a wing so I can add it to my collection of TypeR badges and racing stickers (no i dont have any) but for pure practical application. Thanks again for all the responses.

9

Originally posted by NeoFreek
A wing on a FWD car does nothing at all. Its only for the looks. A better upgrade would be to stiffen your rear springs so you have less weight transfer. It increases your acceleration and it doesn't change the look of the car.


or rather you meant provides a better launch...

There are a few more changes than just the wing.

Take a look on the camber on the front and rear wheels. The front wheel have around 0 degrees camber angle which gives the car much grip on the front wheel, and the negative camber angle on the rear which gives the car good stability when the car is turning.

The negative camber also reduces grip on the rear wheels, but the wing would help to give more grip.

The brakes are BIG, and a rule in braking is that both the front and the rear wheel should lock at the same time, this means if you want better braking performance also the rear wheels must have good grip. If not, the rear wheels will lock before the front, or less brake power can be used because so they will not lock.

The car on the images does only have 300 hp and fwd, but can outrun a 1000 hp Toyota Supra on a track, but okey a season old used car cost around $100k-200k and is not street legal.



By putting stiffer springs on the rear suspension, or by having little downforce on the rear, the grip on the cars rear end will become worse and it's not fun to be passed by the cars rear end in a turn.
Stiffer springs and low downforce on a fwd dragracingcar would probably work fine, but they just go straight forward and does only accelerate, the retadation is done by a parasuit.


Some cars have "wings" integrated with the body, like this fwd car
http://www.whirlwind.nl/~saabcars/NewSaabGallery/9-5_21.htm
The "wing" is placed on the trunk and is almost impossible to see, at least if you don't know it's there.
Audi TT (both fwd and 4wd) was fitted with a wing just because the first produced cars had so little downfoce that the car in high speedes "flew" of the road... if you still think that a wing on a fwd is meaningless, reconsider.

Originally posted by NineTwoAccord
I have always been under the assumption that at high speeds, the trunk will actually raise UP due to high pressure over the trunk and low pressure under the trunk. Is this true?

The part about the trunk raising up can happen, but does not necessarily happen, depending on the details of the geometry and the air flow over it. You've got the pressure gradient backwards, though. High pressure above the trunk and low pressure under it would force the trunk downward.

Originally posted by ivymike1031


The part about the trunk raising up can happen, but does not necessarily happen, depending on the details of the geometry and the air flow over it. You've got the pressure gradient backwards, though. High pressure above the trunk and low pressure under it would force the trunk downward.

oops, yea thats what i meant thanks ;)

Originally posted by ivymike1031


I have to disagree - it is not uncommon for a long narrow wing to have a lift-over-drag ratio of 10 or more. That's not typical of what you'd find on a car, but it does show that there's not a fundamental law saying drag=>lift. In fact, it's my understanding that gliders have L/D closer to 20. (as do some high-performance aircraft, operating at certain altitudes)

Furthermore, I'd like to point out that (contrary to popular belief, even amongst automotive engineers) a properly designed & placed "spoiler" can actually reduce the wake area, and thus drag, of a vehicle. Usually this type of spoiler manifests itself as a slight overextension of the trailing edge of the trunk deck, not a protrusion from the top of the trunk. It's worth noting that the 2003 Civic hybrid will have such a spoiler. From a recent article about the civ hybrid:

"Aerodynamic enhancements include a refined front bumper, engine under cover, rear floor side under covers and a trunk spoiler."

"A rear spoiler has been added to reduce turbulence behind the vehicle."

Not sure if it's the lift/drag ratio, but I was told that some high performance gliders have a 57:1 ratio, 57 feet over, 1 foot down!

Originally posted by SaabJohan
There are a few more changes than just the wing.

Take a look on the camber on the front and rear wheels. The front wheel have around 0 degrees camber angle which gives the car much grip on the front wheel, and the negative camber angle on the rear which gives the car good stability when the car is turning.


Its a little hard to tell the exact attitude of the cars in the pictures you posted but it appears both the front and rear wheels have some negative camber, but it may also involve what the car is doing at the time the picture was taken (heavy cornering, ect).

But your generalizations on camber are just that. Under straight line acceleration and braking having the drive wheels (front wheels in this case) with near 0 camber is desired to get the largest contact patch for best performance. Under lateral loads that's not case though. The stiffest sidewall tires will still deflect somewhat under heavy loads. It depends on the weight, roll, and tire characteristics, but you generally want at least -.5 degrees (and often more) camber under heavy cornering loads. What camber you run statically on the front is a compromise of the above factors.


The negative camber also reduces grip on the rear wheels, but the wing would help to give more grip.


While going straight, yeah, but who cares? When going straight on a FWD the rear tires are just along for the ride. But take a look at the brakes on the 50/50 balanced C5 or Z06. Nice heavy PBRs on the front and comparatively wimpy single pot calipers on the rear. Even on a 50/50 weight distributed car the fronts carry the lion's share of the braking duty, because the weight shifts forward as a function of the location of the CG and axles.

Its a function of the rear suspension, but they are probably cambered more because their grip matters much more while cornering then while going straight.

The brakes are BIG, and a rule in braking is that both the front and the rear wheel should lock at the same time, this means if you want better braking performance also the rear wheels must have good grip. If not, the rear wheels will lock before the front, or less brake power can be used because so they will not lock.

Most street cars use proportion valves where the brake line pressure of the front and rear vary linearly with pedal pressure to some point where the rear pressure becomes nearly constant while the front continues to grow proportionally to pedal pressure. Most race cars use duel mater cylinders (front and rear) with a balancer bar that adjusts the proportions of each. In the latter setup both the front and rear line pressure vary with pedal pressure though out the operational range. The prop valve setup is more flexible. The duel MC setup is more precise with in a small range, and since when race cars brake its always at or very near the limits that's what's used. That and the degree of safety redundancy it offers.


The car on the images does only have 300 hp and fwd, but can outrun a 1000 hp Toyota Supra on a track, but okey a season old used car cost around $100k-200k and is not street legal.

Wow, that's a lot. Especially considering you can put together a World Challenge Car for a fraction of that and still be street legal (what I drive to work everyday).

But I'd take you up on the Supra challenge. A drag Supra, yeah of course. But other then its surprisingly heavy, Supras can make killer track (the curvy kind) cars.

BTW, speaking of big brakes, take a gander of page 9 here:

http://www.baer.com/catalog/baer_color_brochure.pdf

12 piston calipers. That's just beautiful. :)

Originally posted by Someguy
Its a little hard to tell the exact attitude of the cars in the pictures you posted but it appears both the front and rear wheels have some negative camber, but it may also involve what the car is doing at the time the picture was taken (heavy cornering, ect).

I have seen the cars for real, they have the wheel angles as I described.

While going straight, yeah, but who cares? When going straight on a FWD the rear tires are just along for the ride. But take a look at the brakes on the 50/50 balanced C5 or Z06. Nice heavy PBRs on the front and comparatively wimpy single pot calipers on the rear. Even on a 50/50 weight distributed car the fronts carry the lion's share of the braking duty, because the weight shifts forward as a function of the location of the CG and axles.

Its a function of the rear suspension, but they are probably cambered more because their grip matters much more while cornering then while going straight.

The racecar drivers probably cares. Without the wing they will have grip on the rear wheels during acceleration, and that is the only time, not during braking and in curves. When do they need the extra downforce, yep thats right, the times the don't have it. When would the car most likely loose its traction, in the curves, and often they go off the track as a result (sometimes they get a little help from the other cars on the track).

The brakes on the Volvo TWR S40 racing car (the car on the images I posted) is Alcon 8 piston calipers on the front with 378x28 mm discs.
On the rear it's Alcon 2 pistoncalipers with 290x10 mm discs.

You have right about the brakes, but a wing will help you to get more traction on the rear wheels, and you can then use better brakes on the rear.

Most street cars use proportion valves where the brake line pressure of the front and rear vary linearly with pedal pressure to some point where the rear pressure becomes nearly constant while the front continues to grow proportionally to pedal pressure. Most race cars use duel mater cylinders (front and rear) with a balancer bar that adjusts the proportions of each. In the latter setup both the front and rear line pressure vary with pedal pressure though out the operational range. The prop valve setup is more flexible. The duel MC setup is more precise with in a small range, and since when race cars brake its always at or very near the limits that's what's used. That and the degree of safety redundancy it offers.

Streetcars today is often using the fifth generation (i think it was 5) Bosch ABS system with EBD, this will deliver the brake power to the wheels that needs it.
All the things you mentioned is just so the rear discs don't lock before the front. And if you have more grip on the rear wheels you can get better brake performance just because the rear discs can brake harder without locking.

The point you mentioned is around 0,3g m/s^2.

Wow, that's a lot. Especially considering you can put together a World Challenge Car for a fraction of that and still be street legal (what I drive to work everyday).

But I'd take you up on the Supra challenge. A drag Supra, yeah of course. But other then its surprisingly heavy, Supras can make killer track (the curvy kind) cars.

And that's the price for a used one. Just the 300 hp 2 litre NA engine cost around 100k (when it's new), the 6 speed sequential gearbox 50k, brake calipers 7k, discs 500 each and so on.

Brake pressure regulator (105 kB)
http://217.31.167.83/~edlund/others/brakepressureregulator.JPG

The racecar drivers probably cares. Without the wing they will have grip on the rear wheels during acceleration, and that is the only time, not during braking and in curves.

The downforce produced by the wing is a function of the speed of the air going across it. It doesn't matter if the car is acellerating by 100 mph, braking by 100 mph, or just cruising at 100 mph. Acelleration has nothing to do with it.

Streetcars today is often using the fifth generation (i think it was 5) Bosch ABS system with EBD, this will deliver the brake power to the wheels that needs it.

Modern ABS systems negate a lot of the function of prop valves, but prop valving is still important for trail braking, and step in.

And that's the price for a used one. Just the 300 hp 2 litre NA engine cost around 100k (when it's new), the 6 speed sequential gearbox 50k, brake calipers 7k, discs 500 each and so on.
That's a heck of a lot for the engine and tranny. You can get a 4 speed sequential Jerico tranny for about $8k, but for rear wheel drive only and a 2 L NA engine won't be at all happy with only 4 gears. You mean 7k just for the front brakes right? Both combined run a bit more.

During the acceleration grip on the rear is created without the need of a wing, but not during braking and at constant speed.

I think I even saw a fwd dragracing car with a wing... I could be wrong, the image was pretty bad.


7k was just for the calipers, don't know if that was for all four or two.

The gearbox is a xtrac, don't know the exact price but it was around 50k, www.xtrac.com

The engine is also mounted further back in the engine bay. The driver is also moved a bit closer to the rear, I think it's also moved a bit more to the center of the car.
The drysump on the engines allow it to be placed lower in the car.

And another funny thing, the adjustable pedal set cost 1500, expensive pedals.

hey guys, i've been following along, post by post and i just want to say thanks for the replies. this is the type of info i am looking for. i am getting the impression that a street car isnt going to find much use unless on a highway and under maybe an emergency situation. or unless i plan to drive it on the track. i'd like to get my car on sebring, occassionally they have races here and we can get on the track. thanks again!

I think what I would do is try to find a factory spoiler from a similar car. The spoiler on a Plymouth Duster would probably have been great for my LeBaron (Don't think I needed it though). That should be a good compromise. Not huge slowing you down, not for looks, but something that has been tested in a wind tunnel before (just not on that particular car).

Originally posted by Porsche
Not sure if it's the lift/drag ratio, but I was told that some high performance gliders have a 57:1 ratio, 57 feet over, 1 foot down!

Porsche,

The ratio you're referring to is most likely the "glide ratio," but I think that glide ratio and L/D are pretty close to the same thing, at least when talking about conditions where the plane is not accelerating:

If the plane is not accelerating, but it is flying at a slight down-angle at a steady speed, then the lift generated is equal to the weight of the plane. If the plane can move forward 57 feet (against drag) using the energy it recovers by simultaneously moving down 1 foot, then the drag force is 1/57 of the weight of the plane, and hence L/D is 57 for this condition.

Interesting...

As a matter of fact, the Audi TT had be to fitted with a rear Gurney flap because of stability complaints. Mistake > _The car, however, has an AWD drivetrain.

The point still stands. :D

Originally posted by 454Casull
As a matter of fact, the Audi TT had be to fitted with a rear Gurney flap because of stability complaints. The car, however, has an AWD drivetrain.

The car is available with both front wheel drive and 4 wheel drive.

Here is a post I made about how wings and spoilers work (mainly spoilers, though)

A spoiler can add drag (porsche 911 turbo, the 'whale tail' years).
A spoiler works on the Coanda effect. That is, air (or any gas or liquid) flows along like the surface it was on. Therefor, on a car, it goes DOWN the back, meeting the air from the bottom. This increses drag, but the air moving that way kinda (a little bit) decreases lift. Now, as far as I understand it, a spoiler causes the air to go up momentarily, flowing STRAIGT behind the car, not as much going down. This decreases drag. Now, the air UNDERNEATH the car has to come UP to the rear of the car, increasing the distance it has to travel, and therfor increasing speed and decreasing pressure going up (lift).
Now you see how it works. (they are in capitals just to highlight important stuff, not trying to make you look dumb. I have done that unintenially in the past )

That is a spoiler, the small 'lip' thing on the back of a car. It has nothing to do with aviation (actually, it does, but not for this reletively simple stuff)
A wing is a device that is an upside down airfoil. It decreases lift, but increases drag. If it is small enough, the drag will be slight. Sometimes it can actually decrease drag by letting the air out quicker and more efficiently. This all depends on a gazillion factors that are hard to understand.

Most magazines call small wings spoilers, which they are not.

Heres another example. On the 911 Turbo, it has a spoiler at first. Then it rises up into uninterupted air, in effect a wing. A true definition is hard to come by, as most people us the terms when they shouldn't.




So a real wing that makes downforce wont make a huge deal at 80mph, but may make some understeer, more noise, and lower gas mileage. It will do the last 2 even if it doesnt work, though. If you put a lip spoiler at the front, you wont decrease understeer much, and would probably decrease it. But you dont need a rear wing unless you are doing seriously fast turns, and you dont want the rear of the car swinging crazily around.