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Old 07-23-2009, 05:37 PM   #1 (permalink)
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Sedan Kammback?

I've been pitching around ideas for aero mods for my car for a year now. I'm starting to formulate an idea that I think I can actually do that might really help. Looking for some guidance and hoping to encourage other coupe and sedan owners.

Many recent sedans and coupes, including my 8thcivic, have the trunk angled slightly downward. Between this preexisting angle and the shortness of the trunk compared to a whole car, I think that this presents advantages in boattail or kammback construction in that the tail can be smaller in all dimensions.

http://img10.imageshack.us/i/boatc.png/

I took the approximate tangent line of the trunkline towards the rear and chopped the tail section from the plane Basjoos used as a model starting at that angle area to make that image.

I am under the impression that this would only actually work if the airflow were still "attached" to the body across the trunk lid area. Is this correct?

I recall a white Nissan sedan that fashioned a coroplast boattail similar in shape to this, using the rear doors to secure it. Has this worked well?

I envision starting with a kammback that follows this shape but does not go all the way out. I hope it would be mountable using the trunk lid in some manner, and not the rear doors. I would want it to be temporary so that I would only put it on for my highway trips. I would also want it to mount in such a way that doesn't damage the finish of my year-old Civic. Perhaps some sort of rubber material would be ideal for the interface between the kammback and the stern area.

I invite any kind of discussion and advice!

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Old 07-23-2009, 05:50 PM   #2 (permalink)
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All the Kammback ideas I've tossed around in my head for use on my Jetta always end up with some kind of permanent hing/pin locations added to the body. Though my car is 20 years old, and its sole purpose in life is eccomodding. Attaching to the trunk lid wouldn't work so good for me because of my WVO tank in the trunk. If I ever do make a Kammback, it will have hinges made into the roof where the rain gutters are. This way the Kamm could lift like a hatchback to give access to the trunk lid and allow it to open.
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Old 07-23-2009, 05:51 PM   #3 (permalink)
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I would start at the top, ie the end of the roof. Then you know you won't get detached airflow.
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Old 07-23-2009, 06:04 PM   #4 (permalink)
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Well I know starting at the roof would be ideal. However, I just don't see myself doing that. It would be a substantially greater undertaking.
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Old 07-24-2009, 02:52 AM   #5 (permalink)
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Well I know starting at the roof would be ideal. However, I just don't see myself doing that. It would be a substantially greater undertaking.
I think starting from the roof would be easier than extending from the trunk hatch. It's easier to make side supports, and it doesn't increase the length of car.
Check out Groar's uglyback. He make a short Kammback, short enough to allow normal operation of the trunk cover, but still gives an aeroadvantage.
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Old 07-24-2009, 01:33 PM   #6 (permalink)
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http://ecomodder.com/forum/showthrea...back-7577.html

Here is how I did mine. I didn't want to drill into the car either.

http://ecomodder.com/forum/showthrea...tml#post100224

Here is how I started my partial boattail, attaching to the parts in the first link. It was originally going to just be a kammback. You might be able to do something similar.
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Old 09-27-2009, 07:45 PM   #7 (permalink)
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Could this be considered as a Kammback

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Old 09-28-2009, 02:41 AM   #8 (permalink)
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Could this be considered as a Kammback
The angle of the photo isn't the best, but it appears that the spoiler is bulged in the middle. It would be better if it were flat and angled slightly down. Of course, you can always A-B-A-B test it
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e·co·mod·ding: the art of turning vehicles into what they should be

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Piwoslaw's Peugeot 307sw modding thread


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Old 09-28-2009, 03:12 AM   #9 (permalink)
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I'm just gonna say "No". I'll go ahead and add to it: "Unless you use it for a mounting point for an actual Kamm extension."
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Old 09-28-2009, 03:27 AM   #10 (permalink)
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it's difficult to tell what that thing will do without a wind tunnel. intuitively i'd say it's the wrong shape with the bulge messing with the original roofline shape. so it depends on what it was designed for. as i look out of the window at the mording traffic quite a number of hatches and mpv's passing have an oem lip "spoiler" which curves up slightly...

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