Ok im sittin here bored as hell, should be studying for my physics exam, but Im gonna post my thoughts. Ok we all know the drag coefficient relates to the aerodynamics of the car and affects speed, performance and miles per gallon. The higher the number (the coefficient), slower the car's performance. The lower the number, the better the car will perform (duh). Drag coefficient is proportional to { (gravitational force) / (inertial force) } and is used in momentum transfer in general and free settling velocities and resistance to flow calculations in particular. Err, I wont go into that detail, but I will tell you what ive come up with.

Taking a drag coefficient for my car (1998 integra) .320....combining that with certain factors:
Air temperature: 65 F
Barometric Pressure: 29.38 in. Hg
Relative Humidity 55%
@ sea level with no headwind nor tail wind.


Power loss due to drag...(if my calculations were right) would be around a 50 hp loss at 100 mph. at 130 mph it could be up to a 100 hp loss....145 mph @ 150 hp loss.

Thats a lot of wasted power

Well anyways....sorry its a long, not important post. just thought i would share my stupid *** thoughts with you guys.

 

just image in if u were in the mountains on a super hot day (95 F) with 90 % humidity

 

True, but there are other things to look at.....Cold air is more dense, thus will slow you down more, but however having that fatty intercooler will give you some more power....id like to do some research on the toss ups on that....but it would be hard because when you slap the car on a dyno....you dont have the wind smackin the intercooler in the face so its not at its full potential....arrh....many questions i have...

 

Just for kicks....




notice...the green is the aerodynamic loss, the blue is tranny, white is tires, and total power loss in red.


[Modified by CDooMe2, 4:25 PM 7/21/2002]

 

Where did you get this number from?

 

i think a good portion of the drag coeffecient comes from the wheel and undercarriage parts of the car. i noticed that vortech supercharged civic that was doing the top speed runs had a lot of work done to the undercarriage and was also lowered.

for a street going car, its hard to lower the coeffecient without compromising handling and suspension travel.

 

Body Kit

 

interesting....I knew that wind was a strong force....but dammm.
100+ hp is amazing

 

i'll bet you a case of beer and a pizza that an overwhelimg majority of body kits have worse drag coeffecients than stock integra or civic front ends.

 

falcon, you are exactly right....more surface area = greater drag coefficient (most cases)

 

I think the Insight has the lowest coefficient of drag...then the second is the lexus LS400 (or is it ES300?) and Toyota Avalon...neither look anywhere as sleek as some other cars, but apparently work...

I remember reading about a Kiwi with a CRX that made a fiberglass pan for the entire undercarriage and I think it made a pretty good difference...

 

Cd = D / (A * .5 * r * V^2)

The drag coefficient Cd is equal to the drag D divided by the quantity: density r times half the velocity V squared times the reference area A.

Most cars id say have a Cd of about .3 to .5



[Modified by CDooMe2, 6:37 PM 7/21/2002]

 

Gee i wonder how my 89 Astrovan would stack up. The thing has the aerodynamics of a cinder block, it has hit 90 mph though

 

cartest...that program kicks ***! I built my dream car on there many a time.

 

I didnt say just any body kit. There are actually body kits that do work.

 

.5 HOLY!!!

these days low .3, high .2's
check out the lexus ls430, 0.26, which is one reason why they're so quiet...

 

yep back in the 50's they had some cars with as high as .7, talk about some ****.....Ive been doing some more thinking/researching and ive come to find, just because you have a low Cd, doesnt always make it better, remember you want some downforce, otherwise **** could hit the roof, it seems to be very hard to design a car with low Cd(mostly for the fuel efficiency reasons), and to still have a well handling car. Also the ones that come out really good in the wind tunnel, look uglier than a monkey's ***.


[Modified by CDooMe2, 11:23 PM 7/21/2002]

 

CRX's have around .28

I wonder what a 4G HB has?????

-Dustin

 

would an aluminum wing help the aerodynamics of my car??

those F1's have 'em.. so i guess it would help??

 

haha i think i read somewhere that the nice "shopping cart" look spoiler actually will slow you down up to like 5 mph on your trap speed in the 1/4...depending on the severe size of the shopping car spoiler. haha

 

This is one hell of a thread and I have always wanted to talk about this. I always hear people say, "I ran xx.xx @ xxxmph and it was 95deg weather." and I think to myself that they were probably going faster in the heat, but how much less hp were they actually making.
Ambient air temp plays a big role on how much power you make, but at the same time it affects how we "move through the air" so to speak.

Mase, I think it would be an awesome project to see the relation of air temp vs. whp to ET would be. Im sure a formula can be made, if there isnt already one. Dont forget to add CD. Does somebody have a listing of cars, such as the EG, EK, DC2 and CRX that has the drag coeffcient?

Lets keep this thread going because its very interesting indeed. Also, dont you just love what physics class does to you?

art

 

 

there is drag....
then there is downforce....
f1 cars make 1g of downforce at around 60mph
at 200mph supposedly the ferrari f40 could drive upside down
when someone tells you they went 150mph in a integra ls with minor mods, then you know for sure that they are lying.... thanks to the graph!

 

the new saleen s7 can drive upside down at only 160!!!!

 

show me...