Air Dam and Front Undertray - Page 5 - Fuelly Forums

Click here to see important news regarding the aCar App

Reply
 
Thread Tools Display Modes
 
Old 04-17-2007, 06:02 PM   #41
Registered Member
 
Join Date: Mar 2007
Posts: 1,138
Country: United States
Thanks, Brelandt!
__________________

__________________
Bill in Houston is offline   Reply With Quote
Old 05-21-2007, 07:31 AM   #42
Registered Member
 
Join Date: Mar 2007
Posts: 1,138
Country: United States
Air Dam and Undertray Update

Well, after a month of air dam and front undertray use, it seems that it has not improved my highway mileage. It may have actually lowered it. It definitely does keep the front end more stable at speed. So maybe it is actually causing some downforce, which I would gladly trade for higher mileage.

So here's my question. If I use a manometer and find out that the air pressure above the undertray is higher than the air pressure below, is there something that I can do that would allow me to trade downforce for lower Cd? Like maybe lowering the back edge of the undertray?

I will probably try it no matter what, but just wondered if anyone thought I had a chance of being successful. ;-)

Update:
In mid June I did lower the trailing edge of the undertray a little closer to the ground. It seems to make less downforce now. I assume that this improves my Cd.

Thanks for the input!
__________________

__________________
Bill in Houston is offline   Reply With Quote
Old 06-03-2007, 01:24 AM   #43
Registered Member
 
Join Date: Apr 2007
Posts: 155
Country: United States
It looks great especially considering your frugality.

Fortunately for me, I have no need for an airdam. My car is already quite low to the ground.
__________________

atomicradish is offline   Reply With Quote
Old 07-22-2007, 03:38 PM   #44
Registered Member
 
Join Date: Mar 2007
Posts: 1,138
Country: United States
For the sake of completeness, this is a link to the coast down testing that I eventually did. Show something like 10% improvement in Cd.

http://www.gassavers.org/showthread.php?t=4419
__________________
Bill in Houston is offline   Reply With Quote
Old 07-22-2007, 05:11 PM   #45
Registered Member
 
Join Date: Jul 2006
Posts: 57
Country: United States
i looked your job Bill: very good!
__________________
.................................................. .....
my English is bad, but I do not surrender!
.................................................. .....

fabrio is offline   Reply With Quote
Old 07-22-2007, 07:15 PM   #46
Registered Member
 
Join Date: Mar 2007
Posts: 1,138
Country: United States
Thanks!
__________________
Bill in Houston is offline   Reply With Quote
Old 07-22-2007, 07:38 PM   #47
Registered Member
 
Join Date: Jul 2006
Posts: 57
Country: United States
you have made a job much cleaning up (professional), and the result of your test is indicative about quality of modification.
I have written a simple excels for to calculate the acceleration or drag: it is necessary to read the GPS NMEA after a procedure equals to Coast-down Test, but at the moment, it is not capable of CD result, but to calculate only complessive resistance (drag+rolling resistence)
__________________
.................................................. .....
my English is bad, but I do not surrender!
.................................................. .....

fabrio is offline   Reply With Quote
Old 07-22-2007, 08:10 PM   #48
Registered Member
 
Join Date: Mar 2007
Posts: 1,138
Country: United States
Do a few runs coasting from 65 mph to 60 mph.
Do a few runs coasting from 15 to 10 mph.
Dump the data to Excel. For the high speed runs and the low speed runs, plot speed vs time and draw the best-fit line. From that best fit, figure out what to put into the calculator at http://web.archive.org/web/200408030...DownCalcs.html
That calculator will calculate your Crr and CdA separately.
__________________
Bill in Houston is offline   Reply With Quote
Old 07-23-2007, 04:18 AM   #49
Registered Member
 
Join Date: Jul 2006
Posts: 57
Country: United States
yes, the algorithm is simple.
it must calculate the negative acceleration in high speed (that it allows to obtain the sum of all the resistances), after, it must calculate the negative acceleration in slow speed (that it allows to obtain only the rolling resistance)

for last, it is necessary to embezzle the CRR at the total resistance, the result value, it is the aerodynamic drag!

in my excels file, this I have not still implemented it, only, because, I have not still had way to make a test with the car
__________________
.................................................. .....
my English is bad, but I do not surrender!
.................................................. .....

fabrio is offline   Reply With Quote
Old 02-17-2008, 07:14 PM   #50
Junior Member
 
Join Date: Feb 2010
Posts: 4
Country: United States
I am new here but thought I would help with a source for VG's if you have not found them yet.
http://www.vortekz.com
and here is a picture of the car, I am getting started on side skirts when I found the site.
Attached Thumbnails
Click image for larger version

Name:	S1030004.JPG
Views:	269
Size:	93.5 KB
ID:	1019  
__________________

johnf36 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Strange fuel-up calculations with odometer. Honva Fuelly Web Support and Community News 3 04-27-2012 05:30 AM
Why doesnt my car show up under 'browse vehicles'? frederic73 Fuelly Web Support and Community News 4 06-17-2011 04:00 AM
Gas Log? GasSavers_Kraig General Discussion (Off-Topic) 3 08-16-2006 02:21 AM
Looking for Insight wheel numbers GasSavers_Ryland General Maintenance and Repair 3 07-08-2006 11:02 PM
Car wrecked. Compaq888 General Discussion (Off-Topic) 80 06-15-2006 12:23 AM

» Fuelly Android Apps
Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 07:06 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.