Aerodynamic panels, questions/ideas for improving CD and mpg of 6g Options

[ricochet1490]

Has anyone ever heard of addition panels to improve the coefficient of drag (cd) of our cars? Sites like ecomodder have all the people making stupid looking stuff to gain mpg, but imo our cars look too good for that to happen. So I was thinking, what if we made panels that either A) looked good on the car, or B) couldn't be "readily seen" - aka made out of lexan or something.

Any Thoughts, ideas? I think if we could shape some clear panels to deflect air around our bucket head lights, and some to keep the air off the spoiler (but still using the spoiler for mounting/looks), we could probably gain at least a few mpg. It might be worth looking into if some cheap lexan could be found.

[stephen_lee]

underbody panels would be the first thing id look into. really thin aluminum would deflect the wind and keep the weight down, plus protect the underbody from elements (not much for collision as theyd have to be thicker = weight = loss in mpg)

[ricochet1490]

underbody panels would be the first thing id look into. really thin aluminum would deflect the wind and keep the weight down, plus protect the underbody from elements (not much for collision as theyd have to be thicker = weight = loss in mpg)

That has crossed my mind as well. Its not like the underside of our cars are extremely rough anyway, but I think if we made an underbody panel that was "dimpled" like a golf ball then we might be ahead. The dimpling creates a turbulent boundary layer of air(which is why golf balls are rough), and as you can imagine, air sliding past air is less friction than air past metal. Wonder what $$ would look like on that....

[stephen_lee]

im thinking more of the engine bay and over the gas tank/spare tire well. pretty rough areas IMO. and u can make that effect with... a hammer lol

[ricochet1490]

The engine area is pretty rough for sure as is the spare tire, just doing those would probably save on $$ and weight.

On a side note I found myself looking for a "facebook" like button on your previous comment lol very funny

[stephen_lee]

ballpeen hammer on thin sheet metal would create dimples very well.

and i look for that like button on the forum all too often...

[ricochet1490]

ballpeen hammer on thin sheet metal would create dimples very well.

and i look for that like button on the forum all too often...

haha- but you do make a good point. a decent break could probably bend the aluminum where you need it to be, a drill for the holes, but I think I would want some kind of "template" to get even dimplage on it. something with maybe 6 even hemispheres that could be pressed into the aluminum (that is of course if I ended up making a lot of them for people on here in the very distant future) . I know you'd never see it, but it helps to look good. lol

[stephen_lee]

im really not sure what the gains in mpg would actually be, and its really only on highway use that youd see it as well

[SwissFerdi]

One of the rarer Celica parts is the set of clear headlight covers. I imagine they smooth out the front end quite a lot.

[stephen_lee]

I'd like to see a set of those

[azian_advanced]

some GM cars use front air dams mounted under the radiator support (where it's barely noticeable) to reduce drag. also lowering the car will also help. but putting dimples on panels won't do anything noticeable. and stephen_lee is right, improving aerodynamics is only worthwhile if you do a lot of highway driving. if that's the case, you should look into getting low rolling-resistance tires.

[BonzaiCelica]

pics moved to second page

This post has been edited by BonzaiCelica: Dec 30, 2011 - 1:55 AM

[ricochet1490]

^^ now see that's what I was talking about. The headlight covers I bet would be a worthwhile investment as far as aerdynamics is concerned. But the thing of it is, right now I AM doing a lot of highway driving. 1000miles every ten days with about 85% highway.
But I was thinking about some sort of air dam, again made so that it looks good, but my fluid mechanics class is screaming in my ear right now lol. I have to think that the aerodynamic changes would HAVE to be worth at least 1.5-2 mpg. If we reference the mythbusters episode (not where the idea originated but a good example) of when they added clay to the car and then dimpled the clay. They saw a jump in mpg from something like 26 to 29. Now obviously they did the whole car with the exception of the underside, this would just be the underside, but the point is the same.

Using the equation Fd=.5*p*v^2 * A * Cd found here http://en.wikipedia.org/wiki/Drag_equation - And assuming this page is correct http://en.wikipedia.org/wiki/Automobile_drag_coefficient , our cars have a Cd of .32.
And then knowing how Cd is calculated from the drag equation wiki and the Moody diagram found here http://en.wikipedia.org/wiki/Moody_chart . The Fd COULD be significantly affected I think.

If we take for instance the frontal area of our car, estimated to be about 18.84 sq ft. - found here http://www.newcelica.org/forums/showthread.php?t=263442
a velocity of 55 mph, the p(density of air) at 72 deg F with a .32 Cd........ 55mph =24.59 m/s...... 18.84sq ft = 1.75 sq. met. .......... 72F = 20C so p = 1.204 kg/m^3

Fd = 203.845 N at 55mph If we reduce the Cd by even .02 so our new Cd is .3 our new Fd is 191.1. This may not seem like much but it's a difference of 6.25%. Which SHOULD correspond directly to the car not having to work as hard to push through the air. does this mean a 6.25% increase in mpg? maybe, maybe not, but even at 3.125% increase at a standard of 30mpg means a 1mpg increase to 31. All 6.25% gives us nearly 32 mpg. Anything beyond a .02 change could be really significant. Significant enough to pay for itself in a year? who knows- i don't really care to do the calculation right now.
To me the reduction in weight only serves purpose for accelerating type driving. If on a FLAT highway, your car doesn't care if the back seat and speakers are in the door or not. (also proved by Mythbusters episode on dimpling with clay.... that car gained 400 lb because of the clay and on flat ground got better mpg)

Sorry if I went over anyones head, but my engineering brain was screaming

Also I kinda want to relate this to the other topic, of which you may or may not have seen, hence my reference of the weight. http://www.6gc.net/forums/index.php?showto...mp;#entry928916


This post has been edited by ricochet1490: Aug 15, 2011 - 4:43 PM

[azian_advanced]

front headlamp covers will only increase fuel economy by about 0.2 mpg. this was tested on a Renault LeCar back in the 70s. (Source) If you read the article, they also test the same car with sideskirts, with and without an air dam, as well as adding an air dam on top of another (double air dam lol!). they concluded that a single air dam (4" in height) gained an extra 1.0 mpg and the double air dam an extra 0.8 mpg more. i've created a slideshow for a small presentation i did last year on this same topic if you want to have a read (link - password: 6gc).

[BonzaiCelica]

wow there ricochet. You lost me. To technical I'll say and a lot of equations.

I was also thinking that with my gt4 bumper it has a lot of openings on the front. Maybe some way to close the bottom section off, where the foglights are, for track cars??

One thing I'd like to see, is put the gt4 riser blocks on my car and buy the oem replica roof spoiler made by vincent doggy and go do a windtunnel test with those headlights covers. Just to see how much downforce the rear spoiler gets. And then swap it out for the TRD Spoiler.

[OOBE]

The engine area is pretty rough for sure as is the spare tire, just doing those would probably save on $$ and weight.

On a side note I found myself looking for a "facebook" like button on your previous comment lol very funny

That made me lol.

[Neon90424]

just drive behind an 18 wheeler lol

[stephen_lee]

just drive behind an 18 wheeler lol

drafting FTW. i gained about 3 mpg for this

[nics]

just drive behind an 18 wheeler lol

drafting FTW. i gained about 3 mpg for this

Works for me all the time

[Neon90424]

drive behind an angry suv driver aswell plenty of caddies with people rushing like they missin out on the birth of their child