1989 Chevy Celebrity 4 door - kammback ideas - Fuel Economy, Hypermiling, EcoModding News and Forum

wagonman76 · 01-10-2009, 02:20 AM

Attached are some ideas I have been thinking about for the Celebrity, which is currently parked for the winter season. Obviously they are arranged from hardest to easiest.

The section over the trunk lid needs to be hinged so it folds away from the window, so I can open the trunk, I have attachment ideas. So anything more than the trunk lid part will need to a 2-piece deal. My bumper is heavy chromed steel with several attachment holes (for a VR body kit that was offered from the factory) so I can attach something lightweight with little worry. Lighting is not a concern, I can add lights and rewire with no problems.

Any thoughts or comments as to if any of these would be better? Or if there is anything different that would probably be better to try?

Bicycle Bob · 01-10-2009, 03:20 AM

I think the first shape is the only one likely to help much - the others seem prone to separation, especially if any smoothing is done up front. Perhaps you can make a single large shape and hinge it at the roof, so that it can lift up along with the trunk lid. Or, it could replace the trunk lid completely.

aerohead · 01-10-2009, 02:46 PM

I agree with Bicycle Bob,and would choose the top for greatest drag reduction.----------------- The bottom image might be a compromise and with that,I would include a rear spoiler angling up and to the rear to intersect the teardrop template line.Can't be steeper than 30-degrees from horizon or drag starts to go up again.--------------------- Since the two central images fall below the teardrop line,they would as Bob has mentioned,be in separated flow and of no benefit.-------------------------- If the length issue scares you,remember,you can chop it off vertically wherever you like.Just know that the length is what is buying the drag reduction.

trikkonceptz · 01-10-2009, 03:09 PM

If going with the first design, it will look more like the fast back montecarlo's of the 90's.

Anyhow, you can make it as a three piece spoiler. The side pieces, made of metal or plastic and attached directly to the rear quarter panel and roof. The middle piece made of plexi glass and attached to the roof and the side pieces. Wouldn't look to bad and if you hinged the mounting point at the roof and attached it to the trunk with a single pillar at the edge of the trunk, you could still open you trunk and use it. All you would need to add are some pieces of velcro to keep it attached to the side pieces while driving.

wagonman76 · 01-11-2009, 12:37 AM

Thanks guys for the input. I was even wondering if I even had the teardrop in the right place.

I read somewhere about the best cutoff point being at 50% of the overall section or it increases drag. So I take it that means the height of the straight part of the cutoff should be 50% of the total height of the car. If so then I could cut #1 shorter. Is there any truth to that, or is longer really better? I just took it back to a straight part of about 8" high or so, enough for lights and a license plate.

Also, if I ended up going with just a trunk piece, it sounds like it would be best to still follow the teardrop. Which would be easier so when I add the back piece, it will still follow the teardrop.

I am not going to drill into the body, even though it would make the design a little friendlier. The trunk would have rails that clamp to the trunk lid edges, and a windowed shell that snaps over it, probably with spring pins or something that can be used without tools. Whether or not it would hinge would depend on the geometry. Then the back piece would bolt to the holes in the bumper, and probably to the anchor holes for the taillights as well.

whitewiz · 01-11-2009, 02:30 PM

I owned a Chev Celebrity Kamm back!
called it a Chev Citation hatchback.

wagonman76 · 01-12-2009, 01:24 PM

Yeah the Citation was basically just a Celebrity hatchback. 98% same underpinnings. Different nose clip, different back end, different dash. But you could bolt in a Celebrity dash if you wanted, all the bolt holes lined up. I thought once about getting a Citation and making it a Celebrity hatchback, or even cooler, getting a Phoenix and making a 6000 SE hatchback.

aerohead · 01-13-2009, 05:46 PM

Quote:

Originally Posted by wagonman76

Thanks guys for the input. I was even wondering if I even had the teardrop in the right place.

I read somewhere about the best cutoff point being at 50% of the overall section or it increases drag. So I take it that means the height of the straight part of the cutoff should be 50% of the total height of the car. If so then I could cut #1 shorter. Is there any truth to that, or is longer really better? I just took it back to a straight part of about 8" high or so, enough for lights and a license plate.

Also, if I ended up going with just a trunk piece, it sounds like it would be best to still follow the teardrop. Which would be easier so when I add the back piece, it will still follow the teardrop.

I am not going to drill into the body, even though it would make the design a little friendlier. The trunk would have rails that clamp to the trunk lid edges, and a windowed shell that snaps over it, probably with spring pins or something that can be used without tools. Whether or not it would hinge would depend on the geometry. Then the back piece would bolt to the holes in the bumper, and probably to the anchor holes for the taillights as well.

Wagonman,when they discuss 50%,they're talking about cutting the body off when it has tapered ( top and sides )to 50% of the vehicles frontal area,wherever that occurs.At that point the car would have a drag coefficient on the order of 0.21,if everything else was properly shaped.

wagonman76 · 04-24-2009, 02:45 PM

I had a couple hours today and it was nice out so I got started on the kammback frame. The angle is pretty close to the teardrop I drew in earlier, plus the measurements on the car were pretty close too, to the nearest inch. The back bar ended up 6 1/2" high instead of 6", I will probably go back and lower it to 6". The long strip is just a piece of flat bar laying there to show the angle. Does it seem like a decent angle, or do think I should make it shallower or steeper?

I plan to finish the kammback by welding a full frame of the 1/8" x 5/8" flat bar that I can get in abundance from the scrap pile at work. This will make it light and rigid.

I was tossing around window ideas, and for starters I plan to stretch a heavy shower curtain liner over it, held on by retainers of the same flat bar. I bought one at Walmart for $6 and they are decently transparent. I may do lexan later on if this ends up working well, and if I have more to spend, they cut the engineering dept to 4 day weeks because things have been slow.

MetroMPG · 04-26-2009, 12:48 AM

Nice to see this moving ahead!

Do you happen to know if you have attached flow on the end of your trunk lid? (I'm guessing you may not, based on the rear glass being so vertical - so separation happens at roof height.)

If you don't, you stand to gain nicely from the kammback.