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Discussion Starter · #1 ·
Does anyone know if lowering the altima or adding the ground effects actually improves (reduces) wind resistance? I noticed the '02 camry has a .28 CofD and the stock altima has a .32CofD. This means the Camry uses less energy to go the same speed as we do in our altimas.

It would be nice to know if any of the available mods actually improved more than looks.

Anyone live near a wind tunnel? :D

OpalBlue ;)
 

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loss

i'll take the .04 gain in resistance it won't matter when I blow buy some boring guy in a boring Camry.
 

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Dosen't everyone have a wind tunnel :)

Actually to answer your question you need to know the frontal area of the car as well - the Cd is only one part of the equation.
 

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It seems that spoilers atcually lower the drag CF. I now on the maxima's the SE's with the spoilers have a .31 CD but the GXE and GLE are .32. Lowering the car should help a little bit too and a properly enginered aero kit should help also. I remember on my 95 max when I lowered it and added a Stillen Body kit it became quite a bit faster in the top end. Before lowering and adding a body kit the best I could do was 138 MPH(over and over again) and when I added aero mods in stretched the needle well into the 140's. Not exactly a scientific approach by any means but it sure did seem to help.
 

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Discussion Starter · #7 ·
If you watch any import sports car racing, you can tell that lowering, ground skirts, and wings must help in some way since all the cars seem to have them. I've read that stopping the wind from passing under the car (lowering and adding a front low wind deflector) greatly reduces drag created when the wind passes the rough underside of a car. I've also read that wings (spoiler) can reduce the turbulance created when the wind over the top rolls over the vacuum created by the squarish butt of most cars.

But poorly designed variants of ground effects and spoilers can hinder as much as help.

Maybe someone with a nicely lowered car and ground effects (skirts) can compare their pre-modded top speed with their post-modded top speed. Of course wind becomes a factor, so perhaps two runs in opposite directions would be needed.

I love the idea of improving performance with great looking mods. But the cat (curious) in me wants to quantify that gain, if any, before spending his cash.

On a side note, I've been looking at the new Toyota Matrix as a potential second car, and it comes with ground skirts. The mechanically identical Pontiac Vibe does not. Getting data on their respective CofD's should be revealing.

OpalBlue ;)
 

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Lowering the vehicle and adding front splitters will reduce the swirls and vortices generated by the "dirty" undercarriage. Cd's are confusing because like a fraction, it's relevant to the the facia of the vehicle.

NASCAR is the picture of aerodynamic efficiency. The cars are limited by their shape and the aero engineer's task is to make that shape more efficient. Unlike GT's, SP's and Formulas, stockers do not prioritize downforce because they need the speed in the super speedways. Look at how the bodies are smoothed out, no large cavities, extensive use of non-aerodynamic ducts. The rear wing is a downforce instrument but only to the extent of balancing handling at speed.

So yes, lowering and spoilers will reduce your Cd, but for what? Name me a .27 Cd car that you can't blow the doors off in a 3.5.
 

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virtuoso1 said:
Lowering the vehicle and adding front splitters will reduce the swirls and vortices generated by the "dirty" undercarriage. Cd's are confusing because like a fraction, it's relevant to the the facia of the vehicle.

NASCAR is the picture of aerodynamic efficiency. The cars are limited by their shape and the aero engineer's task is to make that shape more efficient. Unlike GT's, SP's and Formulas, stockers do not prioritize downforce because they need the speed in the super speedways. Look at how the bodies are smoothed out, no large cavities, extensive use of non-aerodynamic ducts. The rear wing is a downforce instrument but only to the extent of balancing handling at speed.

So yes, lowering and spoilers will reduce your Cd, but for what? Name me a .27 Cd car that you can't blow the doors off in a 3.5.
How about a G35 :D .27 CD normaly but with the aero package it's .26. I could still blow the doors off of it because it's auto only and I have a few mods too, but still :D
 

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Discussion Starter · #10 ·
by virtuoso1
So yes, lowering and spoilers will reduce your Cd, but for what? Name me a .27 Cd car that you can't blow the doors off in a 3.5.
But for what? Better MPG. We all aren't about racing or blowing other car's doors off. My Altima is a 2.5.

OpalBlue ;)
 

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OpalBlue said:
But for what? Better MPG. We all aren't about racing or blowing other car's doors off. My Altima is a 2.5.

OpalBlue ;)
So when are installing your NOS kit so you can run with the big boys? ;)
 

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Discussion Starter · #12 ·
OhTwoAltimaSE said:


So when are installing your NOS kit so you can run with the big boys? ;)
No NOS for me. It's my wife's Altima, and she already has a heavy foot.

But I get to replace my old Nissan Pickup at the end of this year, so I may just opt for a 3.5SE and have all the speed I can stand without needing NOS.

Or then again I may get me another Nissan truck. If only the altima designers would take whack at it. It could be better looking. ;)

OpalBlue :)
 

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Air is only one of the many forces a vehicle must overcome at speed. Internal friction from the engine, transmission, the friction of the tires on the ground, etc., all come into play. Also, downforce which is usually a necessity in a fast car, adds drag as well. If you check the numbers, the very fastest vehicles do not have the lowest coefficient of drag.

Spoilers can be used to "clean up" the airflow of the car, lessening turbulence that is created as the vehicle displaces air as it moves through it. They can also be used to create downforce, which would increase the drag of the vehicle possibly.
 

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StanzaPower said:
Air is only one of the many forces a vehicle must overcome at speed. Internal friction from the engine, transmission, the friction of the tires on the ground, etc., all come into play. Also, downforce which is usually a necessity in a fast car, adds drag as well. If you check the numbers, the very fastest vehicles do not have the lowest coefficient of drag.

Spoilers can be used to "clean up" the airflow of the car, lessening turbulence that is created as the vehicle displaces air as it moves through it. They can also be used to create downforce, which would increase the drag of the vehicle possibly.
The G35 is said to have 0 lift and has one of the very best CD's on the market. What do you think about that?
 

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emax said:

The G35 is said to have 0 lift and has one of the very best CD's on the market. What do you think about that?
Zero lift doesn't mean there is any downforce.
 

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As far as I know, the rear spoiler will only increase the CD, becasue the rear spoiler increase the surface area, so as the friction. But the spoiler will help the car hold on the road better by inducing downward force on the wheels during high speed driving. My 01 Celica has spoiler with 0.31 CD, however the 01 Celica without spoiler has 0.30 CD. An all around skirt may help to reduce CD. Hey! Why not add a beak, it will fly like a Concord.:D :) :D
 

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I guess "0 lift" means there is no uplift force created by air current while the car is running. The car will be more stable with all its weight sitting on the four wheels. Airplane use the air up-lift force to take off. You do not want your car fly like plane, don't you!

:p :p :p
 

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Maybe I am Nuts but

Please engineers correct me if I am wrong. The spoiler on the Alti is in now way designed to provide any handling benefits. It is cosmetic in nature. The shape and angle of the spoiler would not, in my observations, add any down force to the rear wheels, which would be dumb any way for a front wheel drive car. If anything it adds drag and weight to the car, but it sure looks sweet and that is what I'm all about.
 

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Re: Maybe I am Nuts but

wild willy said:
Please engineers correct me if I am wrong. The spoiler on the Alti is in now way designed to provide any handling benefits. It is cosmetic in nature. The shape and angle of the spoiler would not, in my observations, add any down force to the rear wheels, which would be dumb any way for a front wheel drive car. If anything it adds drag and weight to the car, but it sure looks sweet and that is what I'm all about.
Most spoilers on cars are purely cosmetic. Only a few have functional ones.
 
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