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Old 11-30-2009, 07:56 PM   #11 (permalink)
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Looks familiar
Can't wait to see how this comes along !

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Old 11-30-2009, 08:03 PM   #12 (permalink)
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Did you ever find that MX-3 rear hatch glass that we talked about ?
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Old 11-30-2009, 10:25 PM   #13 (permalink)
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450 WHP from the 1.6L ? B16 ? Dyno proven?

Need to see pics / videos asap! Any links to share? Once fully aero-modded you are going to have a real highway monster.

That kam-back is looking good! Any pics of the bare frame? I see your challenge on the side angles. I think a lot of your problems might be aided by just shortening the overall kamm length. That's quite a commitment as you have it now. I think you'd get a large % of the potential gains even if it were 1-2 ft shorter.... no?

Also kind of looks like you need another hard break on the sides. If you keep the angle between panels low enough, separation on the rear piece shouldn't be tooo bad.

I decided to sketch it:
It made 418whp at Daves Smith's Kellogg Idaho "Dyno Jet" on low boost 28psi on pump premium. On race fuel running 35 psi it should be easily over 450whp.

I will have to take some pics of the framework.

I think I need to shorten it also thanks for your drawing

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Awesome! In for results, my ghetto kammback fab turned out to be a dud. Back to the drawing board.
You need to get back on your project. I need another del sol to campare notes with.

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testing

--------------------------------------------------------------------------------
If it's at all possible,I would encourage you to tuft-test the tail before you commit to the design.
Anything above 20-mph ( on a dead calm day ) will tell you what you need.
It's hard to tell from your photos,but it looks like there is a sudden,angular transition at the roof,and reflex at the sides especially below the beltline.
If so,you'll have immediate separated flow ( exactly what you're not looking for ).The flow will reattach on top with some efficiency loss.I'd be suspect to the sides,as there is not as much energy available to sustain flow.
What you've mocked-up holds much promise,and a quick test would soon tell you whether or not to cement your design.
I would love to tuft test but as of right now the engine is torn down for inspection. The angle from the roof line down is 11 degrees. It hard to get the angle right. I was going to make it only 5degrees but it I'm not to sure on how to make the frame work?
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Old 11-30-2009, 10:27 PM   #14 (permalink)
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Looks familiar
Can't wait to see how this comes along !
I told you that your art work inspired me!!! LOL
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Old 12-01-2009, 01:06 AM   #15 (permalink)
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OK guys I need your help. I'm thinking of shorting the rear tail by two feet.

As of right now its just a hair under four feet from the rear of the car.

I would also put angles on the rear panel.

Like this


this would give me more width down at the bottom where its needed to decrease the angle I have now.

Thought and opinions please???
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Old 12-01-2009, 01:11 AM   #16 (permalink)
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Originally Posted by aerohead View Post
If it's at all possible,I would encourage you to tuft-test the tail before you commit to the design.
Anything above 20-mph ( on a dead calm day ) will tell you what you need.
It's hard to tell from your photos,but it looks like there is a sudden,angular transition at the roof,and reflex at the sides especially below the beltline.
If so,you'll have immediate separated flow ( exactly what you're not looking for ).The flow will reattach on top with some efficiency loss.I'd be suspect to the sides,as there is not as much energy available to sustain flow.
What you've mocked-up holds much promise,and a quick test would soon tell you whether or not to cement your design.
Heres another pic of the roof line. You can see it better from this angle. Its very slight in the transition, but mabye it needs to be more level with the roof line???

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Old 12-01-2009, 01:26 AM   #17 (permalink)
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Angry

In my old kammback thread, I was told the transition should be 10* to keep attached airflow. After building mine, i ended up with 13*, not sure if that is what affected my negative mpg readings.

Also, I was told by MetroMPG that the transition from the top to the side should be rounded, which i haven't figured out yet. Otherwise (correct me if im wrong MetroMPG) it would create vortices (spelling?) in that area.

BTW: my results: On a 100 mile roundtrip drive with cruise control set to 65mph. Ambient temperature both trips 61*F, filled up at 2:30pm both trips. Using the same gas pump.

without kammback = 45mpg
with kammback = 41mpg

*angry face*

BTW2: so jealous how shiny your paint is
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Old 12-01-2009, 01:32 AM   #18 (permalink)
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Originally Posted by jedi_sol View Post
In my old kammback thread, I was told the transition should be 10* to keep attached airflow. After building mine, i ended up with 13*, not sure if that is what affected my negative mpg readings.

BTW: my results: On a 100 mile roundtrip drive with cruise control set to 65mph. Ambient temperature both trips 61*F, filled up at 2:30pm both trips. Using the same gas pump.

without kammback = 45mpg
with kammback = 41mpg

*angry face*
Oh great... I sure hope I see results. As of right now I have $200.00 in material.

I can change the roof angle (its adjustable) from 8 degrees to 15 degrees. But when I get the sides and the under-tray part done and in-close it in I won't be able to change the angle anymore.
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Old 12-01-2009, 01:40 AM   #19 (permalink)
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Remember this guy?

I don't know why he vanished after doing this but my suspicion is it didn't help fe at all or maybe even hurt it.

Why?

I think he added a bunch of length and a bunch of skin friction (and some weight too) but really didn't reduce the wake area at all.

And in all probability those mods raised Cd in yaw and yes the poor sap doesn't live that far from me so he suffers the x-winds too.

Were I to do such a project I'd mock it up in cheap cardboard or coroplast first, then tuft test. No doubt, even as smart as I think myself to be I'd find that the first version needs changes to make it work. After all has been proven satisfactory... THEN build it "permanently".
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Old 12-01-2009, 02:19 AM   #20 (permalink)
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Remember this guy?

I don't know why he vanished after doing this but my suspicion is it didn't help fe at all or maybe even hurt it.

Why?

I think he added a bunch of length and a bunch of skin friction (and some weight too) but really didn't reduce the wake area at all.

And in all probability those mods raised Cd in yaw and yes the poor sap doesn't live that far from me so he suffers the x-winds too.

Were I to do such a project I'd mock it up in cheap cardboard or coroplast first, then tuft test. No doubt, even as smart as I think myself to be I'd find that the first version needs changes to make it work. After all has been proven satisfactory... THEN build it "permanently".
I here ya big time. To the point I have a sick feeling in my stomach.

I'm a performance engine builder and performance EFI tuner. When it comes to aero i can't even make a paper airplane fly right.LMAO

Well if anything I'll have a few bad ass Lexan sheets for sledding.

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