need advice on a rear pan design

[yama916]

Hi everyone, my first post
have a 04 pontiac vibe base with 5 speed
Ive made grill block offs, front pan, tire air deflectors, and just finished the first rear pan. So far, it is just a sheet of alumalite bolted to rear hitch and suspended 1 inch behind the rear sway bar, its 4 feet wide so it barely clears the tires.

My questions.
should I leave the rear extended as seen in this picture? or is it better to trim it closer to bumper?

is it better to make this sheet into a bottom of the box using aluminum sheets? so that no air can get on top of the pan?

I live very close to Chicago downtown, so mostly 50/50 city highway w traffic driving. normally i have been getting 31 per tank, I do use a scan guage and see 37-40 on good days.

after the pan was installed I did a 200 miles roundtrip over this past weekend, had 20+ mph cross wind all day, with temp in the 90s, AC on 100% of the time. I only logged a 29 out and 32.6 return mph at 70+mph cruised. I was disappointed to see these numbers but the winds were so so so strong...

Thanks in advance for your tips looking forward to picking the brains of the experienced.

Yohei

[yama916]

[yama916]

well, i tried to link the pics from picassa but it doesnt come up when I post it. so here is the URL to the pics.

https://picasaweb.google.com/yamaday...eat=directlink

[theholycow]

Welcome. Hotlinking Picasaweb photos is a little more difficult than sites like Photobucket. You have to get the URL of the photo itself, not of the page containing the photo; right-click the image and view its properties to find its address. Then you have to mangle it up manually; just before the last slash '/', you may see s488 or something like that. Change it to s640 or s800 (or a bunch of other sizes that will work). If it's not there, after that last slash, add s640/ or s800/. I think Picasaweb offers an automated way to get those URLs now, along the right margin of the page there's an option to copy an embed address to the clipboard.

Here's one of your photos:


Interesting idea, making it stick out past the end of the bumper. I never would have thought of that. I wonder if there is an advantage to doing that; it is possible. I probably wouldn't want to deal with it being ugly and in the way, so I'd trim it back.

[yama916]

thanks for the help, i guess there arent too many guys here with aerodynamics knowledge... I appreciate your thoughts, if the extension doesnt help in any way, Ill take your advice and cut it off too. Its not really in the way though but I agree its ugly..

I did make another pan that covers the front of the rear axle, ill try to upload it to photobucket.

[GasSavers_BEEF]

one thing you could do is take it off and paint it black or something. that way it would blend it better. there is a guy that used to be on here that was all about some aero. his screen name is basjoos but he has his own site now (aerocivic or something similar) google it. he has a civic that looks like a teardrop. he would be the one to ask.

[theholycow]

User BamZipPow does a lot of aero. Check out this thread:
http://www.gassavers.org/showthread.php?p=157296

I'll be doing some aero stuff on my Buick, too...starting with pizza pan wheelcovers and some coroplast in particularly bad areas.

[GasSavers_BEEF]

forgot about him. he has that awesome little truck