Cd of an EP?

[Hasbro]

Anyone know the drag coefficient of our egg?

[Slip_Angle]

The RSX is .29 so I figure the EP is similar.

[Hasbro]

I hope you're right but think it is higher.

[Slip_Angle]

The link below says it's .33.. It says 2001 Civic Si but the height and width match the EP so I think that's it.

http://ecomodder.com/forum/showthread.php/cda-list-1935.html

[Hasbro]

I'm not very knowledgeable about this stuff but Cda (what is used in those charts) is a multiplication of the Cd value x area. So perhaps Cd takes other factors in. Like a wagon being more efficient than a coupe for instance. I don't know, just wishful thinking. I posted the question on an aero board.

[Slip_Angle]

I'm not very knowledgeable about this stuff but Cda (what is used in those charts) is a multiplication of the Cd value x area. So perhaps Cd takes other factors in. Like a wagon being more efficient than a coupe for instance. I don't know, just wishful thinking. I posted the question on an aero board.

Did you scroll down further and see the list of cars and their Cd that was posted? That is where I found the .33 Cd.

[v1c10us]

you have to take into acount we basically have a kapp back, named for the german guy who designed it, this makes it much more aerodynamic than similiar size coupes.
although you guys with spoilers are really fuckin yourselves, nothing like a massive bump in the middle of a smooth curve to fuck with airflow.

[MOOGEN]

I could sworn that we went over this topic already. Vicious, play nice man no ones gonna be going that fast on local streets and highways to feel the difference anyways. :mwink:

[Hasbro]

Ok, see it now. Rats, was hoping it would be a little better. It's not bad, just not great. Thanks, Slip.

[Hasbro]

The more I read on Cd the more confusing it gets. Our Cd might be .33 but as Viscious mentions about the Kapp back and other things, there's a bit of black art involved.

Moogen, I didn't see anything in my search. Are the old archives available? I've been occupied with another project for a while and when I came back the forum had changed. Which sucks because I had compiled a bunch of info for my project, which is pretty different from most that I have seen.

I plan on pulling 400+ pounds off, a lot of suspension work, and a goal of 40 mpg. I have 250+ off so far and I'm getting around 35 mpg. So far everything has been low bucks but all further development gets pricey. With the weight closer to 5th gen civics the EP would be really something. Now if there was a double a arm kit.....

[SiN05]

to hit 40 mpg it think your really going to have to stretch to get that without sacrificing creature comforts. I think there was a thread like this on the old one. Uping gas mileage cai and fresh filters. Pump up your tire pressure another 10 lbs. as for the aero lowering as someone said, take off spoiler, take off antenna, smaller mirrors, remove rear window wiper, lighter rims, fresh wax....I've been tossing the idea of a getting a 91 honda hatch and gutting it for a DD but haven't pulled the trigger yet.

[Hasbro]

Yeah, I'll do some of those and several other things. I'm not much for comfort, always strip them down . Maybe that's why I'm single. I can get just short of forty now but it's too extreme a form of driving and I also want to rip around corners. I wonder what a Ka24 and 6 speed could get. I used to get 28/30 in my CRV no sweat and 37 once on a trip driving slow.
I was tempted to just do an old Civic or CRX but I want to keep the car a long time so the newer chassis and reliability and I can shove two mountain bikes in the rear cavern.
It doesn't have to be an extreme performer as I have designed and will be building a 750 pound street legal single seater in the very near future. A little more fine tuning and then I will build a scale model, then the actual car. If all figures are correct 1.3 gs won't be a problem. But I digress.

[v1c10us]

I could sworn that we went over this topic already. Vicious, play nice man no ones gonna be going that fast on local streets and highways to feel the difference anyways. :mwink:
the drag difference in your gas mileage would be noticeable at 20mph.
adding the spoiler increases drag, creates an area of low pressure and air turbulence in the flow.
take an egg for example
the air flows cleanly over the top of the egg and follows the line of the egg all the way to the back very smoothly.
Now put a spoiler on the egg.
the air follow the line of the egg and starts to go down, where it suddenly has to jut up and over the spoiler, this creates a swirling right beneath the spoiler. This area of low pressure has to suck the air from behind it and pull it with the car. Not to mention it prevents fast moving air over the top of the car from exiting cleanly, making the entire back of the hatch a big slowy mc slow spot.

you could expect 2-5 mpg differences with an HFP spoiler versus none at all at 80 mph.


edit: those desperate for mileage would do well to purchase aluminum flashing from home depot and run it vertically down the length of the underneath of the car creating a smooth surface for airflow, paying special attention to keeping air from catching in the bumper.
http://pumpngo.files.wordpress.com/2008/04/honda_insight.jpg block the wheel wells too. THe insight has an undercover on the bottom to keep airflow smooth and its one of the slippiest cars around.