Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 10-01-2009, 08:36 PM   #1 (permalink)
Chevy and CB Radio Lover
 
Jammer's Avatar
 
Join Date: Sep 2009
Location: East Kentucky
Posts: 302
Thanks: 13
Thanked 3 Times in 3 Posts
Send a message via Yahoo to Jammer
Smile Do Rear Spoilers / Wings Help Any?

No spam meant, but on this subject I did find a great website to have spoilers purchased, maybe installed on cars:

Car Spoilers including Rear Spoilers and Car Wings - Rear Wings and truck spoilers

Ok, I have an album of pictures showing my 2009 Chevy Cobalt LS Coupe XFE on file with my profile here that shows my spoiler clearly.



I bought the car out right after getting an insurance settlement for a very bad wreck I had, due to my brakes not working and almost getting me killed around a curve. I also got about $5,000 in discounts from GM, my father a GM Retiree, and the dealer that had my car on their lot. I must admit it is a strange feeling having a brand new car with no payments. And my insurance company did not wish to raise my rates nor drop me due to the conditions of the wreck- they did not seem to fault me. (it was my only wreck in my life, and I'm 44) But I was driving a med size 4X4 Chevy Colorado pickup truck that got around 17MPG (20 EPA)- this was rated BEFORE THE EPA REVISED THEIR METHODS OF SCORING MPG ON CARS/TRUCKS. I next got a sub-compact with EPA of 37 Highway 44 possible (as read on sticker on the window). What I am now experiencing is like culture shock. I can now drive to places on a gallon of gas that used to cost me over double that. I feel as if I have been freed from the chains of High Oil because of the vast improvement in mileage.

Back to the topic on hand:

I tried my best to find a Cobalt that had only 4 important requirements:

#1) It HAD to be an XFE
#2) I wanted the color RED (Because Chevy's "Blue" was far too dark for my tastes)
#3) The car HAD to have a rear spoiler.
#4) Spare Tire ($75 for the "doughnut")

The car was no longer in production for 2009, and the team was on break. So I had to pick from the car lots near my home state because XFEs were very rare, and I had no transportation and could not afford to wait months. I was working with a sales-guy and a dealership that I fully trusted due to all of the business my father had gave them over many years. I had many bad experiences with sales people treated me rudely or making assumptions that were false about me, so I was sticking with the dealership I was at. Finally my guy found a car fitting my description, only it also had the $40 option of an ashtray which was only a large ashtray shaped like a cup for the cup holder and a lighter plug for the socket (shesh)- So the car was strip down to standard options except for the ashtray and lighter (which I did not need and gave away), spare tire and jack and the almighty rear SPOILER. It does have many standard features that impressed me, yet things one takes for granted as being standard were not. It does have an awesome stereo system in it that was standard, and that means a lot to a guy that plays music such as myself.


The rear of my car reminds my a little bit of a 1985 Pontiac Fiero GT I once owned that had a spoiler on the rear. Or even a tiny bit like the back of a Corvette. I really likes the looks of a Cobalt Coupe better with the spoiler mounted, (the 2009 Sedan is another story), but I do not expect it helps my MPG any....

So, what do our EXPERTS here think? Generally speaking, or at least with a car like mine, do these stock mounted spoilers help the fuel efficiency even a little bit, or are they just for looks? Could they maybe HURT the mileage some because they are not as high up as real sports cars often have? - And there lays my beef: It seems like on the real expensive sports car, be they street legal or otherwise, their rear wing is normally mounted much higher than on stock cars like mine being sold.

I assume the rear spoiler on my car is at best good for looks, and at worse, it might even be a drag on efficiency.

Experts? (all please weigh in)

Thanks.


Last edited by Jammer; 10-02-2009 at 10:10 PM.. Reason: Added #4: The Spare Tire Option- I forgot that one!
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 10-01-2009, 08:51 PM   #2 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,585
Thanked 3,555 Times in 2,218 Posts
See the mods and tips at the top of the page? Good read, fun and educational.
__________________


  Reply With Quote
Old 10-01-2009, 09:13 PM   #3 (permalink)
EcoModding Apprentice
 
Bicycle Bob's Avatar
 
Join Date: May 2008
Location: N. Saskatchewan, CA
Posts: 1,803

Appliance White - '93 Geo Metro 4-Dr. Auto
Last 3: 42.35 mpg (US)

Stealth RV - '91 Chevy Sprint Base
Thanks: 91
Thanked 459 Times in 327 Posts
In general, a wing is good for traction and bad for economy. Because the racy image sells so many cars, wing-like things are sometimes used to help cure separated airflow over a rear window, which is good, but not as good as a plain fastback.
  Reply With Quote
Old 10-01-2009, 10:05 PM   #4 (permalink)
Chevy and CB Radio Lover
 
Jammer's Avatar
 
Join Date: Sep 2009
Location: East Kentucky
Posts: 302
Thanks: 13
Thanked 3 Times in 3 Posts
Send a message via Yahoo to Jammer
Smile

Interesting. I was afraid that such a device might make the mileage worse.

Frank: Thanks for the tip. I had overlooked the Tips posted here. "my bad"

Still ' would like to learn about more thoughts on this subject.

Peace.
  Reply With Quote
Old 10-01-2009, 10:07 PM   #5 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
Many efficient cars that have "spoilers" really just have deck lid lips/extensions to encourage flow off the trunk to separate cleanly, rather than curving partway down the rear of the car before separating (which increases both lift and drag).

So here's my GUESS: IF your trunk (without a spoiler) has attached flow at its end (and I'm guessing it does), and also a relatively sharp corner in the metalwork transition to the back of the car (no idea), then that raised spoiler probably hurts since it would increase the size of the trailing wake.

But that's only a guess. And unfortunately, I bet the difference would be small enough to be hard to detect in coastdown testing. But you could always try. That would give you a definitive answer.
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
The Following User Says Thank You to MetroMPG For This Useful Post:
radioranger (04-25-2012)
Old 10-02-2009, 02:08 AM   #6 (permalink)
aero guerrilla
 
Piwoslaw's Avatar
 
Join Date: Oct 2008
Location: Warsaw, Poland
Posts: 3,691

Svietlana II - '13 Peugeot 308SW e-HDI 6sp
90 day: 58.1 mpg (US)
Thanks: 1,268
Thanked 721 Times in 458 Posts
How to decide whether to remove rear spoiler to decrease drag, improve mileage.
__________________
e·co·mod·ding: the art of turning vehicles into what they should be

What matters is where you're going, not how fast.

"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell


[Old] Piwoslaw's Peugeot 307sw modding thread
  Reply With Quote
The Following User Says Thank You to Piwoslaw For This Useful Post:
radioranger (04-25-2012)
Old 10-02-2009, 02:27 AM   #7 (permalink)
Master EcoModder
 
Join Date: Feb 2008
Location: belgium
Posts: 663

vectra a - '95 Opel Vectra GLS
90 day: 37.51 mpg (US)
Thanks: 14
Thanked 61 Times in 44 Posts
a quick google revieled an article claiming an 0.32 Cd for both the sedan and the coupe, seems high for the coupe as the cobalt is esentially the emerican equivalent of the opel astra G (same platform differnt body) the astra coupe has an 0.28Cd without a spoiler where the sedan has a 0.29.

the chevy seems to sit a little higher off the ground than the opel (possible softer american suspention vs the astra's hard euro setup?) and with FE not being so important for this type of car in the US (as you say yourself you doubled your milage with this car so chevrolet doesn't need to squeeze every last mpg out of it)

i think the spoiler might add 0.02 or so to the Cd, just a guess though....

loosing the spoiler is possibly the best for FE...beause "real" spoiler are only there to allow for extremely fast cornering wich doesn't matches well with FE driving anyway

than again, if you like it... just drive carefully with FE in mind and you should see a very decent milage on that car anyway
__________________
aer·o·dy·nam·ics: the science of passing gass

*i can coast for miles and miles and miles*
  Reply With Quote
Old 10-02-2009, 02:52 AM   #8 (permalink)
Pokémoderator
 
cfg83's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 5,864

1999 Saturn SW2 - '99 Saturn SW2 Wagon
Team Saturn
90 day: 40.49 mpg (US)
Thanks: 439
Thanked 530 Times in 356 Posts
Jammer -

I'd look into Bonneville Salt Flat cobalts for spoiler inspiration :

Top - 2006 Chevrolet at the Bonneville Salt Flats

Quote:
(from GM Press Release) Chevrolet Sets Three New Land Speed Records at the Bonneville Salt Flats GM Performance Division and its partners from So-Cal Speed Shop set three new land speed records with Ecotec-powered vehicles last week during the 58th Annual Speed Week event at the Bonneville Salt Flats in Wendover, Utah, including the first-ever Bonneville record using E85 ethanol. Ecotec-powered vehicles have now set eight records during the past four years with some form of GM involvement.
If I hade a coupe or sedan I'd spend more time researching this design. However, I can't say that this spoiler has any benefits. It could be for downforce or it could be to "mask" the parachute from the airstream. I just don't know.

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote
Old 10-02-2009, 03:20 AM   #9 (permalink)
Moderate your Moderation.
 
Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
Carlos - Downforce. They use them in NHRA/IHRA as well.

I don't remember the whole reason they work, but I think I remember something about Bernoulli in there, or maybe I was day dreaming during that lecture. Either way, they're there to produce downforce.

OP - Check out the '99ish Pontiac Bonneville - that spoiler is for better aero, definitely. If it weren't there, the flow would curve sharply around the deck lid at the rear, funneling toward the center due to the overall shape of the deck area. It would be bad.

The spoiler, however, is probably neutrally helpful compared to the bare deck lid, since it's tilted up and it's a wierd shape/angle that I'm sure doesn't do much for aero at all.

The rear of the car seems almost perfect for aero from the rear windshield down, visually... it's not , but it seems that it is... if only they hadn't curved the deck lid like they did.
__________________
"¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

  Reply With Quote
The Following User Says Thank You to Christ For This Useful Post:
cfg83 (10-02-2009)
Old 10-02-2009, 03:38 AM   #10 (permalink)
aero guerrilla
 
Piwoslaw's Avatar
 
Join Date: Oct 2008
Location: Warsaw, Poland
Posts: 3,691

Svietlana II - '13 Peugeot 308SW e-HDI 6sp
90 day: 58.1 mpg (US)
Thanks: 1,268
Thanked 721 Times in 458 Posts
Quote:
Originally Posted by lunarhighway View Post
loosing the spoiler is possibly the best for FE...beause "real" spoiler are only there to allow for extremely fast cornering wich doesn't matches well with FE driving anyway
I say: Take it off and use the mounting holes to secure a Kammback...

__________________
e·co·mod·ding: the art of turning vehicles into what they should be

What matters is where you're going, not how fast.

"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell


[Old] Piwoslaw's Peugeot 307sw modding thread
  Reply With Quote
The Following User Says Thank You to Piwoslaw For This Useful Post:
cfg83 (10-02-2009)
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tuft Testing - "Vortekz" vortex generators on 2003 Jetta Rear Window Deezler Aerodynamics 40 07-15-2017 01:56 AM
How to decide whether to remove rear spoiler to decrease drag, improve mileage MetroMPG Aerodynamics 130 02-10-2015 08:50 PM
Dual Fuel, electric rear wheel drive, gasoline front wheel drive bucknmusky DIY / How-to 42 12-27-2012 01:59 AM
Rear Alignment: Drivability vs Economy Southcross EcoModding Central 11 04-22-2009 09:40 PM
tigra AERO PROJECT rear end question fabrio. Aerodynamics 19 03-31-2008 12:01 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com