Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 04-15-2012, 04:25 AM   #1 (permalink)
Too many cars
 
Gasoline Fumes's Avatar
 
Join Date: Oct 2009
Location: New York State
Posts: 1,397

CRXFi - '88 Honda CRX XFi

Insight 256 - '00 Honda Insight
Team Honda
Gen-1 Insights

Insight 5342 - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 65.78 mpg (US)
Thanks: 959
Thanked 675 Times in 396 Posts
Kammback for the Nut Wagon?

I'm thinking about doing it! I wanna break 60 MPG! The hatch is terribly rusted (old pic) and I have a better one, so why not experiment? I don't want to cover the taillights, so I want the Kammback to be above them. Anything goes above the taillights, what should I build? Should I keep the corners, basically mimicking the cars shape like the snow did, or transition to a rounded shape at the end? How long should it be? I don't want to go too far past the bumper. How much angle can I get away with on the top and sides?




__________________

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 04-15-2012, 05:25 AM   #2 (permalink)
Master EcoModder
 
Join Date: Apr 2011
Location: Europe
Posts: 364

ZX - '97 Citroen ZX Monaco
OldContinents
90 day: 61.05 mpg (US)
Thanks: 8
Thanked 31 Times in 25 Posts
I have been told that round would be better than angles, so I did go with round shapes with mine.

One I made is 50cm long from top and top angle is around 10 degrees, side angle is around 15 degrees, but I guess 10 would be better there too.
__________________

  Reply With Quote
The Following User Says Thank You to jtbo For This Useful Post:
Gasoline Fumes (04-19-2012)
Old 04-16-2012, 06:07 PM   #3 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,647
Thanks: 20,313
Thanked 6,288 Times in 3,893 Posts
snow form

Build it like the snow.Go all the way to the bumper and cut in fenestrations for the taillights to shine through on the sides.3rd brake light too.
  Reply With Quote
The Following User Says Thank You to aerohead For This Useful Post:
Gasoline Fumes (04-19-2012)
Old 04-16-2012, 09:41 PM   #4 (permalink)
Master EcoModder
 
Join Date: Dec 2011
Location: Boise Idaho
Posts: 842
Thanks: 39
Thanked 89 Times in 69 Posts
my theory is 15 degrees is the goal on the sides, and 20 is the goal on the top.

pretty cool pic of your car with the snow. build it like that.
  Reply With Quote
The Following User Says Thank You to drmiller100 For This Useful Post:
Gasoline Fumes (04-19-2012)
Old 04-17-2012, 12:34 AM   #5 (permalink)
Master EcoModder
 
Sven7's Avatar
 
Join Date: Aug 2011
Location: Warren, MI
Posts: 2,456

Boo Radley - '65 Ford F100
90 day: 13.28 mpg (US)
Thanks: 782
Thanked 665 Times in 408 Posts
Yeah, just use some acrylic sheet on the sides. Try drmiller's angle and tuft test it to make sure it isn't losing flow attachment. If you can, transition to rounded at the end. It'll help with side winds.
__________________
He gave me a dollar. A blood-soaked dollar.
I cannot get the spot out but it's okay; It still works in the store
  Reply With Quote
The Following User Says Thank You to Sven7 For This Useful Post:
Gasoline Fumes (04-19-2012)
Old 04-18-2012, 09:34 PM   #6 (permalink)
Sport Compact Driver
 
Join Date: Apr 2012
Location: Lolo Mt
Posts: 623

Celica Gts - '84 Toyota Celica Gts
Sports Cars
90 day: 26.32 mpg (US)

The Bee - '96 Mazda B4000 4x4 Base
Pickups
90 day: 20.39 mpg (US)
Thanks: 56
Thanked 62 Times in 55 Posts
Quote:
Originally Posted by aerohead View Post
Build it like the snow.Go all the way to the bumper and cut in fenestrations for the taillights to shine through on the sides.3rd brake light too.
What he said!
  Reply With Quote
Old 04-18-2012, 10:19 PM   #7 (permalink)
EcoModder
 
Join Date: Jul 2008
Location: North Central Alabama
Posts: 572

Big Salsa - '04 Toyota Sienna LE

Silver - '10 Toyota Prius III
Thanks: 110
Thanked 123 Times in 71 Posts
Do kind of like I did with my SedanKamm, start out mimicing the car, and then go to a "chamfered" back end, which mimics round. My top angle started out at about 10deg and went a bit steeper (maybe 15deg?) about half way down (it had a post stiffening it in the middle). The sides can come in at the same angles IF you have good attached flow on the sides like you do on the roof. Otherwise take it a bit more easy. Test for attached flow with a tuft test. They are easy to do if you have windows, which I would suggest so you can see when driving. Build in and around all tail lights, as Phil said.
__________________
  Reply With Quote
The Following User Says Thank You to wyatt For This Useful Post:
Gasoline Fumes (04-19-2012)
Old 04-19-2012, 12:59 PM   #8 (permalink)
Too many cars
 
Gasoline Fumes's Avatar
 
Join Date: Oct 2009
Location: New York State
Posts: 1,397

CRXFi - '88 Honda CRX XFi

Insight 256 - '00 Honda Insight
Team Honda
Gen-1 Insights

Insight 5342 - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 65.78 mpg (US)
Thanks: 959
Thanked 675 Times in 396 Posts
Thanks everybody! I'm still thinking about what to build it out of. And it needs to open with the hatch, but that shouldn't be a problem. I have a collection of LED 3rd brake lights I can use, so I don't have to worry about covering the factory one. The bottom and back will most likely be left open. Is that going to be a disadvantage?
__________________

  Reply With Quote
Old 04-19-2012, 01:16 PM   #9 (permalink)
Master EcoModder
 
Sven7's Avatar
 
Join Date: Aug 2011
Location: Warren, MI
Posts: 2,456

Boo Radley - '65 Ford F100
90 day: 13.28 mpg (US)
Thanks: 782
Thanked 665 Times in 408 Posts
The more enclosed and lengthened you make it, the more benefit you'll see. If you can make it go around the sides and bottom, do it. If you can make it extend two feet back from the hatch, do it. It's very much what you put in is what you'll get out.

Other mods like wheel covers and skirts and belly pans will compound the benefit.
__________________
He gave me a dollar. A blood-soaked dollar.
I cannot get the spot out but it's okay; It still works in the store
  Reply With Quote
Old 04-19-2012, 01:29 PM   #10 (permalink)
EcoModder
 
Join Date: Jul 2008
Location: North Central Alabama
Posts: 572

Big Salsa - '04 Toyota Sienna LE

Silver - '10 Toyota Prius III
Thanks: 110
Thanked 123 Times in 71 Posts
Disadvantage of the bottom being left open will only be seen if you have good flow under the vehicle to begin with. Do you have a full belly pan?
I would build directly off the hatch if you have a spare one. Building it this way will let the hatch and kammback open together.
Materials can be a wide range of things... How long do you want it to last?
1) I built my SedanKamm out of a used campaign sign that was made of coroplast. It was very appropriate for the build, and will last a long time even if it's exposed to constant rain/sun/ etc. Coroplast is easy to work with, and easy to come by, just call your local sign shop and ask for prices of both new coroplast, and used coroplast. New it should be about $20 for a 4'x8' sheet, used it is sometimes free. If you get used that has been printed with vinyl, you can take your time and peel the vinyl off (tip, let it sit in the sun for a while and heat the adhesive). If it's campaign season near you, look for guys with big 4'x8' signs, and offer to help take down, and dispose of, their signs after the election. If you find ones that have full color printing (a person's face), it's printed on a large piece of vinyl that is easy to peel off. Mono-color, or even multi-color signs are typically colored vinyl that is cut and applied, and takes much longer to remove.
2) Lots of the big signs are actually Alumalite, which is thick coroplast that is sheeted on both sides with a fairly thick aluminum. This stuff is really rigid. We worked with some, and a guy offered to bend it on his 30 ton sheet metal break, but after seeing it, he decided it was a bad idea! Sharp edges can cut right through heavy leather gloves... ask me how I know. Be careful if using this stuff!
3) There is another sign making material that is aluminum over a foam core. This we did bend on the big 30 ton press, but the operator refused to do more than a few degrees at a time, and would only bend it in the 4' direction. 3 grown men could not make the stuff bend over a 55 gallon drum.
All three of these options come in multiple colors, which you will get to choose if buying new, but have to put up with what you find if getting it used. I don't think I have seen brown for matching your car, but I have seen black, which is pretty stealthy.
4) For windows I used thin acrylic sheet (Plexiglas is a brand name of acrylic, Lexan is a brand name of polycarbonate). I got mine at Hobby Lobby for under $5 by using a 40% off coupon (which they have about every other week). I got the biggest one, and sized my windows to make a single sheet make all the windows (and a grill block for my wife's car). The thin acrylic worked well as windows on the SedanKamm, but worked very poorly as a grill block (rocks go straight through it). Coroplast, on the other hand, makes an excellent grill block, but that's another story.

__________________
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com