Modifications completed and in progress (1991 Honda Civic DX)

[sdecoman]

I have uploaded some pictures into album SDecoman's 1991 Honda Civic DX. Best mpg to date: 44.12mpg combined. Coasting whenever possible, shifting at no higher than 2000rpm and maintaining as high a vacuum as possible. Comments are welcome

Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - sdecoman's Album: SDecoman's 1991 Honda Civic DX

[Patrick]

Can you remount the license plate flush to the bodywork? Angling it should help with drag a little.

Why did you remove the rear spoiler? Got any before pics of it?

[sdecoman]

Fairing in the license plate somehow will be considered once I finalize the rest of the front end of the car.

I took off the spoiler because I think the opening in it was a source of turbulence. I may fill in the opening and reinstall it to see if it makes any difference. It is so short, I think it was more of a design exercise than any effort to carry the air beyond the rear of the car. I have found some pictures of a white '91 Honda Civic Hatchback just like mine and I will add it to my album.

Wheel well covers, then belly pans and then side skirts. Everything will depend on the weather. With an unheated garage, some of this will have to wait until next spring.

By the way, thanks Patrick for viewing and replying.

[AeroModder]

The spoiler actually helps separation, even with that gap. Check out the wind tunnel footage of the new Focus hatchback.

[MetroMPG]

I wonder about removing that OEM spoiler as well. I don't think it's just a styling exercise - it provides a clean separation point at the roof/rear glass transition. It's a common feature on hatchbacks/vans.

Now if you're planning to build an extended Kammback to replace it, that's something else entirely.

But if not, I would have left it on.

[sdecoman]

I am still near the bottom of the learning curve when it comes to aerodynamics but let me say this. With the spoiler on, if the road or street is wet, that back window becomes totally unusable within seconds. It happens each and every time whether it is windy or not.
I would seem to a newbie like me that there is quite a bit of turbulence back there that pulls the air right to the rear window from the rear tire spray and from behind the car and deposits all the dirt there. If I'm wrong that's ok, but I need to here why that's a good thing not just reference to a manufacturer's video which as we all know can be made to show what ever they want.
I could do a tuft test once I get a video camera which until now was an unnecessary expense. Until I can come up with a solution that is better than the what I had, it makes no sense to me to put it back on unless I fill in the gap between roof and the spoiler as at least a test. The holes to mount it are still there and the third eye can mount anywhere.
By the way, as an off-subject question but peripheral to aerodynamics, can anyone point me to a digital video camera that they would recommend. Image stabilization I would think would be a key feature for this kind of work.
Anyways, thanks to all who have replied. If I can't take criticism, I shouldn't ask for comments.

Tom Beno, a South Dakota ecomodder that actually believes that what we are doing here is more important than the stares and derisive comments people will make as they pass you in their gas sucking SUV. You all have just a great day.

[MetroMPG]

Originally Posted by sdecoman

With the spoiler on, if the road or street is wet, that back window becomes totally unusable within seconds. It happens each and every time whether it is windy or not.

That's normal and good, as far as reducing drag goes. Bad, as far as rear visibility is concerned.

A "not sharp enough" transition from the roof to rear surface can both increase drag and lift, which is why the trailing edge of nearly every hatchback roof is "sharp" or has a small extension spoiler like yours did.

Same applies to the trunks of most sedans: transitions are getting sharper and sharper (either in the sheet metal, or with lip spoilers added) to promote a clean separation point and smaller/better organized wake behind the vehicle.

Testing is always a good idea, but that spoiler is a relatively small change that may or may not show up in repeated coast-down tests.