Transam kid 01

iTrader: (1)

8 wins every time

khtm

Holy crap...you obviously don't know the purpose of a spoiler eh?

At high speeds the wind over it produces a DOWN FORCE over the rear of the car. With a FWD car like the Cobalt, this will actually make the handling WORSE...with a RWD car like the RX-8, this should make the handling better, as you have more traction over the wheels that propel the car.

So yeah, the RX-8 has way more reason to have a big stupid wing than a Cobalt

Tirminyl

Anyone tell this car it doesn't need a wing- Maybe everyone doesn't know the purpose of a wing.

Transam kid 01

iTrader: (1)

Street car


He is right in a way...the spoiler is pretty much ineffective until the higher speeds...such as 100MPH plus...then it helps to keep the rear wheels down, giving it better traction...on a RWD or AWD car only

DrDiaboloco

Wings on almost ANY street car give downforce benefits that are largely unnoticeable at street-driving speeds (as in speeds under, say, 85mph). I don't care WHICH end of the car is driven, at an AUTOCROSS a wing is totally useless, unless it's so comically large that you wouldn't want it on your car anyway... The speeds one achieves at an autocross are simply too low.

You also seem to suggest that a HEAVY wing imparts a benefit on a RWD car because their "significant weight comes in handy". I presume you are saying this because it would help with traction. Well, that may be so. Clearly, there's a reason people put sandbags in their '8 in the winter months, and that's for increased traction. However... If you take snow out of the equation, any benefit of the increased weight over the rear wheels will be outweighed by increasing the total weight of the vehicle (which hurts performance) and adding all that weight well above the roll center of the vehicle (which hurts handling, and badly... like at an autocross, for instance).

In reality, trunk-mounted spoilers are typically there for two reasons. First is looks, which can't really be debated. Second is to counteract the natural tendency of cars to produce lift at high speeds. In some cases, those designs are good enough to produce significant downforce, though obviously with a related drag penalty. In most cases, though, the car is probably still producing lift in triple-digit speeds, but less than it would without the aero aids. The FWD car is going to produce the same aerodynamic forces as a RWD car, given the same shell but different drive wheels... Therefore FWD cars have just as much "need" for them as RWD cars.

They are NOT there to increase traction in traffic or improve autocross times. I suspect that you have an anti-fwd car bias here, one that allows you to give a pass to all RWD cars with wings/spoilers but makes you turn up your nose to the same item on a FWD car.

Yeah, you're right. The Cobalt SS IS slower in straight line performance. It's slower by a 2/10 of a second in the 0-60 and 1/10 the quarter mile (and the SS has a higher trap speed), and it's slower by 3 or 4mph in top speed. So, like I said, it's a virtual wash. I don't recommend taking a Cobalt SS lightly, because those are the numbers for the car right off the showroom floor, without any of the power upgrades that GM offers. Any one of those will make the car faster than an '8.

And you're still right, it doesn't have any relevance to spoilers. But you're also still wrong, the Cobalt SS has every "right" to have one, your assertions notwithstanding.

DrDiaboloco

Holy crap! Read above!

I know EXACTLY what spoilers are for. What they are NOT for is "increasing traction only on the rear end of RWD cars because only RWD cars need downforce and FWD cars are going to end up doing loops off the road because it makes handling worse". The latter seems to be the concensus on this thread.

Transam kid 01

iTrader: (1)

Im assuming you are tyalking to me.
A few things...i am muscle biased...but not when it comes to technical stuff. The rear spoiler does improve traction in a sense that when it reaches 100MPH plus, the car is not as firm on the ground as lower speeds. The spoiler adds wind resistance and down force which will help keep the RWs down. Now, there are also front spoilers. These help keep the front of the car down at high speeds. Effectively the same things as the rear spoiler, but for the front

Tirminyl

Point being- To state that ONLY a rwd car would benefit from a wing and a fwd car wouldn't, shows how little the person knows about the purpose of wings, downforce, etc. So with your statement, the design team for the Acura race car should be fired because the wing they added does nothing for the car because it is FWD. And even at the speeds they travel the wing is still pointless because it is FWD.

evilbada1

And Cobalt SS won the first place in Time Attack over Evo, GTR etc...

DrDiaboloco

Exactly. Let's boil this down to the absolute basics.

1- Almost all street cars will produce net lift at triple-digit speeds if there are no aerodynamic aids to counteract that lift.

2- Almost all street cars, especially those that have a sloping rear window and a separate, more-or-less horizontal trunk area at the rear of the car (like sedans in general, and the Cobalt in specific), will produce far more lift at the rear of the car than the front.

3- Almost all cars will benefit from more aerodynamic downforce at the rear of the car than at the front to balance out the lifting tendency or the net downforce on the front and rear of the car.

4- To produce more aerodynamic downforce at the rear of the car, you need to either:

a- spoil the airflow tumbling over the end of the trunk (a spoiler lip) to decrease the lift, or

b- an inverted wing to produce downforce (a "wing")

The points above are completely irrespective of which end of the car is driven. FWD, RWD, AWD, and even a car that has no driven wheels at all and is being pulled by the hand of God will experience the same forces.

khtm

Yeah, a rear spoiler does produce downforce on the rear (and front, but not as much) of a car, but it's more functional on a RWD car...that's my point. A huge wing on a FWD car is just gonna produce more drag and weight than help the front traction. IMO a smaller wing would be more beneficial to a FWD setup.

I still think a wing is better suited to an RX-8 than a Cobalt, at high speeds.

Any mechanical engineers out there? I'm just a pathetic comp eng. BlueEyes?

DrDiaboloco

But... The point of a wing on a street car is not to help "traction" on the drive wheels. It is to counteract the lifting tendency typical to auto bodies that create more lift at the rear than the front. This tendency is more pronounced on so-called "sedan" body profiles like the Cobalt, so contrary to your assumption, the Cobalt probably "needs" a wing MORE than the RX8.

It seems that the prevailing assumption that you have is that RWD cars need more traction at higher speeds, and need wings to press the rear wheels into the pavement. Except in very specific instances that involve VERY high speeds and VERY powerful cars, this is not the case (do we often see RWD cars spinning their tires at 120mph because they don't have traction, wing or no wing??). The wing/spoiler's intent (for applications where it's usefulness is actually designed into the car, as opposed to a stylistic afterthought) is to provide balance to the lift (or downforce) across both axles.

There are obviously cases where the FRONT of the car gets "lighter" at high speeds as opposed to the rear, as well as cars that are designed to have NO spoilers or wings yet attain very high speeds with little or no aerodynamic problems. One car that I know of off the top of my head that needed FRONT downforce more than REAR downforce is the original Datsun 240Z. This car was well-known for the tendency of the nose to lift at higher speeds, and was a car that responded well to a chin spoiler under the front bumper to tame that instability.

Ultimately, I suspect that GM's purpose for putting that oversized wing on the Cobalt (and the same wing on the Ion Redline) has more to do with "gotta look like an STi or an Evo" than aerodynamic reasons... But the truth is that it would need the wing no more and no less than it does NOW if you converted it to RWD. The wing is there for the same reason that it's on the RX8, and for the same reason that the RX8 has dual-oulet exhaust... It looks cool. Or at least it looks cool to the people that buy them.

khtm

Not sure where you get your info from, but the main purpose of a spoiler is to increase the force on the tires, for more grip...but maybe we're arguing the same thing?

From http://www.physlink.com/Education/AskExperts/ae496.cfm

"Cars have spoilers to increase their grip on the road. Normally the weight of a car is the only thing that forces the tires down onto the pavement. Without spoilers, the only way to increase the grip would be to increase the weight, or to change the compound the tire was made out of."

I never said RWD cars *need* more traction at higher speeds than FWD cars, I just said a REAR wing will benefit a RWD car more because it applies more of the force over the tires that are driving the car. This sounds like simple physics to me, but if I'm wrong please provide a link saying otherwise.

Bart!

You guys totally ruined my thread...

KYLiquid

pics at night work best with a tripod and longer exposser

DrDiaboloco

Well how far were we supposed to go with pictures of a Cobalt and an RX8?

Your link doesn't suggest anything that I can or will argue with. My difference is with your extrapolating that information to make the point that a RWD car will get more benefit out of there being extra downforce over the driven wheels. If that were the case, the few full-on racing cars out there that have front wheel drive (the pictured Acura racing car and BTCC cars, for instance) would have outrageous wings or other appendages on the FRONT of the car, and this is categorically not the case. Often these are limited by series rules, but more importantly, the fact that aerodynamic lift in cars that are not DESIGNED to be racing cars is greater on the rear end of the car than the front. THAT is why I am saying that RWD cars don't gain a greater benefit from rear-mounted wings/spoilers as opposed to FWD cars.

I will go look for a link to information that will help make my point.

DrDiaboloco

Okay, here you go. This link best describes what I am talking about, and is one of the very few that references aerodynamics in street cars (most links refer to purpose-built racing cars like F1/Indy and NASCAR "stockers").

The whole page is interesting reading, but check out the force diagram just under halfway down the page, as well as the text associated with it:

http://www.up22.com/Aerodynamics.htm

Perhaps there's a better explanation elsewhere, but I think twenty minutes of Googling is enough for one day.

Special Ringpop

I don't care what anyone says. I have, and will be, a GM supporter for a long time, unless they continue what they're doing.

However. The Cobalt is NO Cavalier.

Bart!

I didn't have a tripod at the time. The cobalt ss is a great car.

BlueEyes

I used those pictures for a report I did in undergrad. I put my professor in or around the car in each picture. It was amusing reading through my report. At least to me. Here's one.

DrDiaboloco

Very nice! Obviously I don't know the guy but I got a good laugh out of it anyway.

Rootski

iTrader: (1)

Let me point something out here. The wings on cars functions in the reverse manner of an aircraft wing, using an airfoil to create negative lift and a camber to deflect air upward, creating downforce. Also, as has been mentioned, they are for looks as well.

However, have you ever felt the wing on a Cobalt SS? It's comically flimsy. Pressing on the middle, you can bounce the thing like a basketball. I find it hard to believe that the wing provides any performance enhancements at all; in fact, i'm willing to bet it vibrates so much at speed the only thing it succeeds in doing is adding drag and looking dumb. Therefore, while wings are for looks and performance, the Cobalt's wing fails on both these points.

Cars don't have to earn their right to a wing... I think certain wings look good on even FWD cars. The Cobalt SS's wing just looks ridiculously large and awkward in my opinion.

And for the record, my 8 has no spoiler.

DrDiaboloco

This has already been pointed out.... Ad nauseum.

So has this.

marvin_rock

You guys are all wrong. My Xmen spoiler that this website dreads so much added 13 HP to my car right after I bolted it on. I havn't Dynoed it yet, but I read it on the internet somewhere so I know it's true. If that Cobalts wing was bigger, it would have totally kicked the 8's ***. Who needs turbo when all you really need is a wing 13 times the size of your car!

khtm

Maybe I'm confused but I think we're arguing similar things, although you still haven't shown me that a wing isn't more beneficial to a RWD car...

I'm a bit slow today so help me out!