Rear Spoilers...debate.

[Super Blue 72]

Super Blue 72,

I'm a little thick at times, can you explain how a rear spoiler helps on a FWD Uncle Ben's Mobile ?

P.G.

It adds 10php (psychological horse power).   

Add the stickers and you'll get 20php. 

[HP2]

I wouldn't go so far as to say that the wings/spoilers DO nothing. I think it is pretty obvious that they provide down force, in some cases, a substainal amount. However, is that downforce necessary in a street car? Probably not. A street car is not pushing the limits of traction in a highway cruising or around town cornering situation to a point that additional force is necessary. NZ, is that what you are refering to as useless?

In my own experience, I know that they begin adding down force and as a result, drag, as low as 60 mph. I have an F body drag car. It runs low 12s at 110 in the quarter. It has been without a rear spoiler until last summer when a came across a really good deal and put one on. It looks cool so I thought why not. This is a duck tail type spoiler like the T/A and AAR, but is a couple inches taller. After installing the spoiler my e.t. increased 2/10s. Reading the incremental times I could see that it began to slow about mid track  when I was in the 60 mph zone. Because the tire clearence on this car is so tight, I could see where the additional downforce was causing the fender to rub the tire in an area it never had before. So, the spoiler is working. I don't really need the additional down force as I've never had a problem spinning the tires on the top end before, so it came back off. The 2/10 disappeared, and everything was back to normal. But when the car is returned to the street, I might add the spoiler just because I like the looks of it. Which ultimately is probably why most of us, ricers included, put them on in the first place.

[Kapteenikosmos]

I can agree with NZ about the spoiler. Those small thingies on the trunk lid are as effective as neon light bars under ricers. I have an old mercedes as daily driver with factory installed spoiler and the general shape of the car is somewhat same as it used to be in the old days so it should be comparable. Anyways when I'm driving in a snowstorm, the spoiler and the trunk lid around it is coated with snow and most of that snow stays there even with higher speeds, so that means that there is virtually no winds (moving air) which could generate any kind downforce for the car.

Pics from the wind tunnel tests for cars can probably be found from the google and if I recall right the roof pushes the wind stream so high that effective vice those little humps on the deck lid are like fly droppings in desert. So in kinda twisted way the ricers have gotten the wing design right. Those ridiculous massive spoilers high in the air might actually produce some downforce by eating those precious little hps their half engines produce.

edit:

Found a pic from new ford mondeo in wind tunnel test. The guy is jetting some smoke in the picture while the tunnel is active and you can see how the wind streams go. Even though the car in picture represents the new aerodynamic design the couple of inches high spoiler wouldn't do anything. Notice how the slope of the leaving smoke stays constant even though the cars bottom end surface varies. That basically means that the rear shape in that particular car doesn't affect on the wind stream path although it will affect on the swirling of the air behind the car but that has nothing to do with the downforce.

[HP2]

Extend that trunk out another 18-24 inches, like most muscle cars have, and it is right in the thick of things. Compared to the sloping deck lid and tapered rear of a Challenger, or the Aspen in my previous example, and it is possible that our older body styles create less drag behind them with out spoilers than thaa newer, more modern design.

[kudakidd]

I don't really care about functionality, but the AAR /T/A spoiler looks best on an E-body.

[Carlwalski]

I wouldn't go so far as to say that the wings/spoilers DO nothing. I think it is pretty obvious that they provide down force, in some cases, a substainal amount. However, is that downforce necessary in a street car? Probably not. A street car is not pushing the limits of traction in a highway cruising or around town cornering situation to a point that additional force is necessary. NZ, is that what you are refering to as useless?

Nope, not useless, they do do "something" but I feel most guys are talking them up BIG time. They really do nothing at all until you're doing atleast 80mph. Any piece of body kit has an aerodynamic effect so of course a wing will too. Just that IMO they really do bugger all for a street driven car driven by your "armature racers" ON the track in the hands of a professional I'm sure it does help somewhat but with the wight these cars have those little wings really aren't going to do much, it's basic principle. Wings on light (2,880lb) Euros or Jappas, they might stand a better chance but you really have to get up to speed to feel the effects.

[Challenger6pak]

I do know this about the Go wing.  If you mount one using washers, etc through the tunk lid instead using of the bottom mount plates, the spoiler will leave the car at around 130.  Been there done that.  LOL.  There must be some kind of force that pulls it through the trunk lid.  Under normal driving conditions, such as obeying the speed limits, it is probably only good for looks. Go fast like HP2 does in a drag car and it may help.

[Carlwalski]

I do know this about the Go wing.  If you mount one using washers, etc through the tunk lid instead using of the bottom mount plates, the spoiler will leave the car at around 130.  Been there done that.  LOL.  There must be some kind of force that pulls it through the trunk lid.  Under normal driving conditions, such as obeying the speed limits, it is probably only good for looks. Go fast like HP2 does in a drag car and it may help.

Yupe, we mounted it different to how they suggested too.
The setup up they suggest is pathetic at best, weak as a sheeps bladder.

How mine were made, now they go right through the entire trunk and not just the skin.
Makes it easier to remove too (if for some unknown reason you have too)

[MJS73]

I don't think there's any question that any spoiler adds downforce, but I have read (and, of course, can't find it now) that the downforce is negligible until you reach very high speeds.  And I'm sure that Chrysler did extensive testing of the spoilers, but I'd bet it was at speed for NASCAR, and not for the road.

Mike

[Jacksboys]

I don't really care about functionality, but the AAR /T/A spoiler looks best on an E-body.

 

[Super Blue 72]

Nope, not useless, they do do "something" but I feel most guys are talking them up BIG time. They really do nothing at all until you're doing atleast 80mph. Any piece of body kit has an aerodynamic effect so of course a wing will too. Just that IMO they really do bugger all for a street driven car driven by your "armature racers" ON the track in the hands of a professional I'm sure it does help somewhat but with the wight these cars have those little wings really aren't going to do much, it's basic principle. Wings on light (2,880lb) Euros or Jappas, they might stand a better chance but you really have to get up to speed to feel the effects.

   They are talked up a bit by the typical street racer guy, more for the psycholoical aspect of it rather than the actual physical properties of the thing. 

Atleast on the ricer cars, all that plastic and fiberglass they add on just detract from performance because all the dead weight they add onto the car (especially with not too much power on tap) detracts from any aerodynamic benefits of the add ons.   

[HP2]

For what it's worth, the following is excerpted from a letter, dated December 3, 1969, from the Chrysler Engineering office to Peter L. V. Hutchinson, manager of the 1970 Trans-Am program. The letter was a discussion of performance factors for the 1970 Trans-Am Cudas and Challengers, and was the "current thinking on the subject." This was the section on aerodynamics.

I'd say that just about sums it up for the non-nascar, most like a street car, type of applications.

In the last year or so, Hot Rod has had a coupe of articles on aerodynamics. Most of their effort has concentrated on their Bonneville applications, but they also provide some good solid info  bout the basic principles as it relates to wings and spoilers and the resulting downforce, drag, and exit turbulence as a result of using various spoilers. interesting reading.

[nivvy]

I have my spoiler on my challenger solely for looks....but if it get me another .1 in the 1/4 mile i'll take it ... 

[Troy]

The term "spoiler" means exactly that - it "spoils" the airflow over the car which reduces lift. Yes, if it's big enough or you're going fast enough it will probably also generate some down force. I did some research about a year or so ago using some really cool wing aerodynamic efficiency software to show what effect those giant ricer wings have (effectively not much - unless you tilted them at a crazy angle). Recently I also did the same thing for Daytona/Superbird wings. The Go-Wing would basically mimic the Daytona wing except the uprights aren't on the end (which helps increase down force). Even as low as 60-80 mph these things can have an effect. At 200+ mph they're enough to crush the trunk lid but an e-body would probably be airborne by then so you'd have bigger problems.

Troy

[71bigblock]

At 200+ mph they're enough to crush the trunk lid but an e-body would probably be airborne by then so you'd have bigger problems.

 

I can see my car lifting into the sky.