Wool tuft pics and video on my Volvo 855
 

I'm the type that has to see things before I really understand them, so I taped yarn all over my windows and drove to work with digital camera in hand. Pretty cool to see the turbulence behind the mirror, the vacuum in my "wake" and the little suction lip (that's what I call it) at the top of the hatch. (Note that there are tufts taped at the very top of the hatch window that you rarely get to see in the pictures because they're getting sucked straight up at speed. At a stop they're all plainly visible.)

Help me decipher this information, if you would. How do I fix some of these flows? A spoiler seems to be the answer for the rear end instead of vortex generators. Check out the airflow at the upper leading edge of the passenger window. It flows up instead of horizontal, maybe from windshield wrap around, or ricochet from the mirror? Both? That one has me baffled.

Here's pics, followed by video. Enjoy.

https://blufiles.storage.live.com/y1p...-peKUzlROTmVfc

https://blufiles.storage.live.com/y1p...4JLWQAeWJxx9Yw

https://blufiles.storage.live.com/y1p...6vdV8m8ysKsSfA

https://blufiles.storage.live.com/y1p...fpb2qThe-HTEQE

https://blufiles.storage.live.com/y1p...4CBe_Z8qsar9JE

https://blufiles.storage.live.com/y1p...ffLjZufNYB3bfI

https://blufiles.storage.live.com/y1p...DnBXZk2kUe3nB0

https://blufiles.storage.live.com/y1p...RyBa-pq7iMPJkM

https://blufiles.storage.live.com/y1p...KSMySHLHUlJKCo

Videos:

https://video.google.com/videoplay?do...38092482&hl=en
https://video.google.com/videoplay?do...66404398&hl=en
https://video.google.com/videoplay?do...10762331&hl=en
https://video.google.com/videoplay?do...42246999&hl=en

WOW excellent idea with the wool testing. Thanks for sharing the pics.
Your 850 wagon has a CD of .32. I wouldn't worry about air flow over the top of the car too much. You can accomplish much more under the car. Specifically the areas head of the front tires and behind the rear tires. Its a real mess.
I took these pics of our NA 5 speed 855. It easily does 34-36mpg at 65mph.

Front
https://farm4.static.flickr.com/3206/...cbddc1746.jpg?

Rear left
https://farm3.static.flickr.com/2111/...c367fe8101.jpg

Rear right
https://farm4.static.flickr.com/3034/...8e55b3e505.jpg

Rear bumper area
https://farm3.static.flickr.com/2184/...0444a5e878.jpg

Does your R have the rear window spoiler? You might want to try the same test with the spoiler removed.

Thanks for the added info. It amazes me that the wag has the same Cd as my Saturn SL, which seems like it would be so much slipperier (word?) My R doesn't have the the spoiler, front OR rear, and it didn't even come with the cool Volans wheels. That, plus it's 200k miles allow me to feel less guilty about modifying a rarish car for mpg. And the fact that my Saturn gets 35-40mpg without any mods whatsoever, so the Volvo gets jealous.

It's time for an oil change, trans flush, etc, so I'll be under the car soon to get creative. I have a couple squares of coroplast I can play with. I would like to make a lip spoiler for the top of the hatch to separate the air flow cleanly, but that may not make as much a difference as cleaning up the under body like you said. That would add to the stealth, since it would still look like just another black wagon.

Where could I find out more info on the CD of a specific vehicle. My car is a 1989 Honda Accord SEI. The winds have been horrible here and my economy is really suffering this week.

I've always been able to find at least something just by searching for the car, with "coefficient" on the Google machine. For instance, I just searched 1989 honda accord coefficient, and on the first page of results, there are 2 differing Cd's. .32 and .33 so there ya go.

Cool! Thanks!

Have to agree with Justin (tjts1) on the mess under the car. The front end between the bumper and front wheels is an absolute nightmare.
At least the area from the IRS and the rear bumper isn't as bad.
I would start with the front end first and clean up that air flow.
The rear area between the spare tire hump and the rear bumper is an easy quick fix.

Here are some pics from my 960. Your 855 looks a lot easier to fix in the back than mine or Justin's

https://farm3.static.flickr.com/2022/...f39e8d.jpg?v=0

With area a head of my front wheels I had boxes build to fill in the empty space.

https://farm3.static.flickr.com/2048/...2a66b1.jpg?v=0

Has this helped reduce eddies and drag under your car?

I have always wanted to help the ground affect on my car.