96-00 Civic Hatch Spoilers
 

Thinking about doing some minor aero mods on my Civic, figured I'd get your opinions on some readily available options.

First is an OEM product for the grey market Civic Type R, fairly ugly but after seeing a number of members on this board with partial kammbacks I thought it may have some merit:

Top view: http://i19.photobucket.com/albums/b1.../ctrwingog.jpg
Profile: http://i19.photobucket.com/albums/b1...n/CivicT-R.jpg
3/4 view: http://i19.photobucket.com/albums/b1...kin/whiter.jpg

Other option is the Spoon spoiler which seemed more areodynamic to me as it just elongated the OEM spoiler found on CX and DX models stateside.
http://i19.photobucket.com/albums/b1...poonWingog.jpg

Are either of these options the least bit aerodynamically sound?

Generally, you want the kammback to angle downwards to decrease the size of the separation bubble forming behind the car. I'd create a sloping kammback that extends as far back as rear-view vision will allow. The length of the rear canted glass creates an excellent opportunity to form a large fairing.

Those spoilers shown will not serve to decrease the trailing wake, but will partially kill lift instead. Your car experiences induced drag, which can be fairly significant. By killing the lift you lower induced drag and potentially improve mileage. I doubt the gains would be as beneficial as a true kammback, though.

- LostCause

I've got a 2000 hatch, and I've wondered the same thing. I think the CTR and Spoon rear spoilers look like they are designed for adding some rear downforce to stabilize the car at high speeds.

In the US, the DX has a spoiler, while the CX doesnt...or at least its really tiny :)

The CX has the same spoiler with the third brake light as your DX, it's just not painted.:thumbup:

But I'll try the Spoon if you try the CTR, what do ya say? :p

Maybe its just a regional thing, but in my area CXs come with the regular rear spoiler, and DXs came with a larger painted spoiler cover, with the CX one underneath it.

Interesting to say the least, where are you located?

This is what I'm currently working with:
http://i19.photobucket.com/albums/b1...n/IMG_0953.jpg

What LostCause said :p

thebrad, what you have there is exactly what all the CXs here in Texas have, but the DX spoilers look like this:

http://www.dmcknight.net/forumpics/dx_spoiler.jpg

Disregard my filthy window, those two reflective vinyl stickers, and the awful art-school painting in the background. :D

Huh, how odd. I always thought the DX spoilers were exactly the same, I've even parked next to one in my condo's parking lot and never noticed that. DX spoilers are definitely the same in CA though.

Pretty cool stuff, we have a lot in common.
VSM EJ6s, failed artists, hypermilers and dirty cars!

:D

The EK aero mods bar has been set:

http://i19.photobucket.com/albums/b1...civicleft_.jpg
http://i19.photobucket.com/albums/b1...civicleft_.jpg

While some of these apply specifically to 99-00 models, and others to the coupe/sedan. We can all steal a little from here or there.

Lostcause is bang on, as usual.

To reduce drag on a hatchback, your spoiler mustn't extend upwards of the imagined line/arc continuing the roof line, in profile view.

These Volvos are a good illustration:

With their C30 "Efficiency" model, among several aero enhancements, they reduced the rear spoiler angle from the regular model, essentially turning it into a roofline extension (extending the slightly downward slope):

http://bioage.typepad.com/photos/unc...efficiency.png

(source)

vs. original model with higher cD:

http://z.about.com/d/cars/1/7/h/T/08...30_profile.jpg

Now if only Volvo would offer the C30 in the US with a fuel-thrifty engine instead of the 227 HP 5-cyl turbo.

Please take a look at these accessories from Honda Japan. I'm pretty much positive the side flaps are a good addition but wonder about the mid-trunk spoiler.

Do you think it allows for air flow reattachment and a smaller wake?

http://img135.imageshack.us/img135/2...vicleftkf1.jpg

http://img81.imageshack.us/img81/256...vicreartl9.jpg

http://img210.imageshack.us/img210/3...icrear2oe6.jpg

Interesting. The top & sides do look proper, but you're right to doubt that lower spoiler. It's too short to do anything useful except gather dust. I think it's very safe to say it would be fully within the turbulent wake.

i'm not sure if that lower spoiler doesn't do anything. dont forget the flow comming of the C pillars is going inwards, so the sides of the lower spoiler will have some effect. but even so perhaps turbulet flow is not beyond guidance.

also it reminds me of the old citroen ax wich had a spoiler like projection in the same place and a much steeper rear window
http://i77.photobucket.com/albums/j5...r_20070326.jpg

the AX has a Cd of only 0.31 wich is rather great for a tiny hatchback so there must have been quite some earo research on it. this spoiler was actually part of the metal hatch so they must have been pretty sure it was doing something right as a flat trunk would have been cheaper and easyer to make.

edit:
come to think of it this car looks very similar to swift/metro's so this sort of thing might be wort for metro owners to look into.

? Front window 'wind-sashes' are helpful for CD?

They most definitely aren't. But I wasn't talking about them. ;)

Ohhh, I see the side flaps on back! I'd like some of those myself! :)

Nice find RPM!

Kind of funny how all the aero junk on the hatch makes it look like a Del Sol...
I wish they could have made it into one full assembly instead of three different parts, but I am going to begin searching for it. Probably going to have to pay a ton for it just because it's "JDM"

If you find those side flaps, please let me know.

Sent out an e-mail asking about them to Password JDM and JHP.

Glad you liked it. :)
You can buy the flaps online from Heel & Toe Automotive.
The mid-trunk spoiler is available from any Honda dealer in Europe. Not sure about the US though.

Thanks for the heads up RPM.
I just got a reply from JHP stating that they are backordered.

Password JDM says they are extremely hard to come by, called HeelToe they said they are getting ready to place an order with Japan within the next three weeks and if you want those try to get in that window because they won't be ordered otherwise.

http://www.heeltoeauto.com/product.php?productid=4617

I think I am going to wait until I have a lot of money to throw at this car before jumping into those but it is nice to know they exist.