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

[ivymike1031]

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

[Someguy]

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.

[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.

[NineTwoAccord]

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

[NineTwoAccord]

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...

[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.

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/Ne...ery/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.

[ivymike1031]

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.

[NineTwoAccord]

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

[Porsche]

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!

[Someguy]

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.

[Someguy]

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.

[SaabJohan]

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.

[SaabJohan]

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

[Someguy]

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.

[SaabJohan]

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.