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.

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)

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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....

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

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

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

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

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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

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

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

I'd like to see a set of those

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.

pics moved to second page

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

^^ 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

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).

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.

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That made me lol.

just drive behind an 18 wheeler lol

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drafting FTW. i gained about 3 mpg for this

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Works for me all the time

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

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HAHAHAHA - lookin for that FB like button again. We had a suburban at one point and from drafting a truck we got 26 mpg out of that thing lol.

I'm pretty active on ecomodder and definitely one of those freaks who drives around with plastic all over my car to get better MPG. But I agree the celiac is too pretty to do that to. I have a GT convertible that I keep covered and take out once a week for fun. My daily driver is a geo metro that looks like a spaceship but gets around 50mpg. It's weird to say but it's actually as much fun of a car in a totally different way. With the Celica all my mods are for style or performance, with the geo, all the mods cost next to nothing and they are only for function and economy. At any rate here are some things that might be interesting for this discussion.

The three mods I would recommend most for saving gas without sacrificing image are:
1) Grill Block or partial Grill Block. The front bumper openings are designed for the worst case scenario (towing uphill in the desert) but under less stressful situations you don't need nearly that much air going into your engine bay. Think of pushing an open cup through water, that's what your bumper mouth is doing to the air. You can block a good portion of the grill and it forces air around the car with much less drag. Best way to do it is is install some instrumentation to monitor your coolant temp (a scanguage II would work) then block some of the grill with cardboard. Keep driving normally and blocking more of the grill until you see the temp rising then back off a bit. This mod also functions to help your car get warmed up quicker and it is most efficient once warmed up. Once you find the right amount to block you can make something pretty like a colored plastic block with home depot mesh across the whole bumper gap to hid your partial block.
2) the belly pan. Our cars are smooth and pretty on the top and sides but under the car is all kinds of stuff for air to get snagged on. For the geo I just bought a 4x8 sheet of coreplast, trimmed it to shape and mounted it under the car. This can be very effective. The other way to get the same effect is install a front lip that extends as low as your lowest hanging suspension, spare tires, whatever hangs down.
As far as dimpling this... Air behaves weirdly and in many cases the air under the car gets pressurized because the bumper pushes a good portion of the air down and the rest goes over the car. when incoming air hits the pressurized air a lot of it swerves left or right toward the wheelwells. It's weird I've seen it in wind tunnel smoke tests. That makes me think that the dimples may not be as effective on a belly pan.
3) the BIGGEST change you can make is driving habits. The Scanguage is awesome, it plugs into the OBDII port and gives you instant readings for mpg rate as well as avg mpg for the trip. It's like a video game trying to set a high score and you can adjust your driving to get the most significant gains.

There's other things of course, the geo has a kill switch so I coast with the engine off a lot but our celicas would lose power steering and possibly brakes so that might not be a good idea. Pulse and glide is a counterintuitive driving method that can save you a ton of gas. It works like this:
Say you get 22 mpg going a steady 55
You could drive for 55 miles and get 22 mpg
now say you drive that same 55 miles constantly flooring it to 60 then putting it in neutral and coasting down to 50
Assume it takes the same amount of time to coast down as it does to accelerate (I'm sure our fast cars would actually coast longer than the acceleration, but for easy math lets say it's equal)
Now say you get only 10mpg when you're pedal to the metal, BUT coasting in neutral your car is at idle and probably gets 50mpg.
So in 55 miles you would spend 27.5 miles getting 10mpg and 27.5 miles getting 50MPG
Average those together and you get 30MPG
And because your average speed between 50 and 60 is 55 it takes you the same amount of time.
You win 8mpg!

The real numbers might be different but the concept actually works, its so weird but try it, you might be surprised.

btw what on earth is making you drive 1000 mi / week?

Ahh ecomodder!! That site gave me wonders on how to get good fuel economy.

Driving with load would be helpful as well. Slow down uphill, coast on downhill!

Not really eco but better air flow.
My mods consists of:
custom full rear diffuser, custom full front end splitter undertray, full under mid panels.
Loads of Carbon and FRP replacement body panels to loose weigh and maybe blanking out my 2 high beams but only after finishing combining the headlights into the 2 outer ones.

@ ACCCELICA
Thanks for the info man! I've actually scoured that site a lot but always wondered what would actually be best for the car. I just bought another one of these things and it's getting built from the ground up with cool/gas milege mods that will look stock for sure. And that pulse driving thing.... wow, yea, very odd in deed.
But i'm driving 1000mi every ten days because i'm currently about 180mi from home working at Honda until I go back to school. 360mi round trip one weekend, 40 mi. driving at home during the weekend, 100mi to work and back during the week plus another 360 round trip the next weekend and another 40 mi driving around. The cycle then starts over at 100 mi during the week, but thats nothing compared to the rest of it haha

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Have you seen any improvement on mileage?. I'm thinking you should easily see over 31 regularly assuming 5sfe/5spd

Dont know yet becasue my engine is out and the car's not ready yet.
Before I was getting around 30mpg anyway if I was driving without a heavy foot. Thats after a really good service.

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Wow, I have never got that. i've got a 5s auto and with a slightly heavy foot i'll see 28.xx sometimes as low as 26.xx 30+ is 90% highway at 70 flat if I'm lucky

vincent's doggy's underpanel is high quality no doubt as some pics that culpable posted on the install. But how about making something of a cheaper material solely to providing less drag on the front under part of the car??? fiberglass was mentioned before or something of plastic similarities... http://www.youtube.com/watch?v=qS8sDkjk0GM



also reposting this pics





>>>>whatthe!!>>>>


This post has been edited by BonzaiCelica: Dec 31, 2011 - 4:43 PM

I am also more active on Ecomodders. So far I've added a partial grill block, front belly pan, rear pan from suspension to the bumper, and lastly, I covered up where the downpipe comes past the subframe. Its hard to tell now that its winter, but last tank had me at constant 32mpg. I use coroplast sheets I got for free from a sign place. 1/8" is plenty thick. If you block the grill, you can use flat pieces with a round cut to match the edges pretty well.

I got 32 mpg without any of that work...