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Fabricating an air dam.
https://slantsix.org/forum/viewtopic.php?t=40704		 Page 2 of 3
Author:  oldblue [ Tue Jul 06, 2010 7:24 am ]
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Yes some of their projects are ugly.Most there are cut and fit.The shapes are what count.Your skill with the materials you use will determine the final look.Go to this site and choose bitmap.Follow instructions on how create you car profile.http://chernyshenko.sesnet.soton.ac.uk/ ... rator.aspx You can use paint in windows.
Author:  Sam Powell [ Tue Jul 06, 2010 7:25 pm ]
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This project led to uncovering at least one major reason why the turbo was not producing boost. Read the ongoing post in the EFI section.

Sam
Author:  Dart270 [ Wed Jul 07, 2010 5:38 pm ]
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Mine is flexible enough to bend on bumps/curbs, but fairly stiff. I haven't had someone look at speed yet. I can tell you it made a big deal on MPG. I just set a new record for any of my Slant vehicles - 401 miles with 14.8 gals driving 65-80 MPH depending on traffic (27 MPG). I averaged 25 MPG for the 1500 mile trip to MA, including 100+ miles of city driving.

I did a little EFI tuning in the 2nd half of the trip, which might have helped a bit, but clearly the airdam must be the big effect. I will be trying some further aero mods like a rear underbelly pan and front grille/light smoothing.

Lou
Author:  emsvitil [ Wed Jul 07, 2010 7:54 pm ]
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Got a picture?
Author:  Dart270 [ Thu Jul 08, 2010 6:03 am ]
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Will try to get some this weekend.

Lou
Author:  Sam Powell [ Thu Jul 08, 2010 6:43 am ]
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Lou, we are on the same wavelength one again. What is interesting is I have been thinking of this stuff for 15 years at least, and only just now started doing something about it. I had a dam such as you have used that I snatched off some junk car years ago, and never got around to simply tacking it on under the radiator core. It still sits in my crawl space, I think.

I would like to send a photo to someone who could post it here as soon as I get a new camera. Things are moving so fast that I will likely be done before I get the camera, so no in-process pictures will be possible.

It is interesting now to look at all new car designs to see their philosophy on air control around the undersides of the car. I finally understand why they sometimes bring the air dams down closer to the ground out near the wheels. I will see if I cannot eventually incorporate that into my design. The challenge is making things stiff enough to work, and stay together with the stress that use puts on fasteners and such, while keeping it flexible enough not to tear itself up. Some of the guys with older Miatas that did not have much in the way of front air dams on them use heavy rubber/plastic weather stripping to create theirs. They get these wide rolls of stuff intended to be used as door sweeps and the like.

Keep in touch on this.

Sam
Author:  Dart270 [ Thu Jul 08, 2010 10:23 am ]
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I have been searching for rolls of such rubber/plastic material, but haven't found anything good yet. I was thinking of landscape edging, but it's either too flexible or too brittle/rigid.

Flexibility is key for street cars like ours. I want to be able to run this thing into the ground or a curb and have no damage. Mine is fine, but looks pretty rough. I think the trash can material I used is molded LDPE or polypropylene or something, but I can't find a suitable roll or sheet of it for less than a million dollars.

Yes, I've also been thinking about this for 10+ yrs, but never got off my duff. It is almost free MPG/HP!

Lou
Author:  emsvitil [ Thu Jul 08, 2010 2:22 pm ]
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Quote:
I have been searching for rolls of such rubber/plastic material, but haven't found anything good yet. I was thinking of landscape edging, but it's either too flexible or too brittle/rigid.

Flexibility is key for street cars like ours. I want to be able to run this thing into the ground or a curb and have no damage. Mine is fine, but looks pretty rough. I think the trash can material I used is molded LDPE or polypropylene or something, but I can't find a suitable roll or sheet of it for less than a million dollars.

Yes, I've also been thinking about this for 10+ yrs, but never got off my duff. It is almost free MPG/HP!

Lou

Try the plastic baseboard stuff you see in commercial buildings. It's flexible and fairly stiff (and comes in black).
Author:  Dart270 [ Thu Jul 08, 2010 3:36 pm ]
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Yep, I thought about that, but haven't found a good source locally or online yet. Thanks!

Lou
Author:  Sam Powell [ Thu Jul 08, 2010 7:56 pm ]
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You can get Polypropylene in 1/16" and thicker and in various size sheets from McMaster Carr for less than a million dollars. I think a sheet of it 1/16"x2'x4' was around $50. You can also get ABS sheets from them for about half that cost. I don't know enough about the properties of these materials to know which would be the best material for a fairing covering the underside of the front. ABS can be chemically bonded, but I don't think Polypropylene can be.


I really think the junk yard is your best friend here. Pick up trucks from the early 90's were still pretty square, and many of them had some sort of air dam hanging down from the bumper.
Sam
Author:  Dart270 [ Fri Jul 09, 2010 6:04 am ]
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Thanks, Sam. I am finding some things online now. PP may be OK. ABS will likely be too brittle/stiff. I have LDPE on there now (trash can), which is flexible and durable. I also found the cove molding in 1/8" PVC, which might work well.

I agree on the junkyard hunting too...

Lou
Author:  sandy in BC [ Fri Jul 09, 2010 6:47 am ]
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Early 80s Chev 4x4 trucks have a great 6" airdam that is very durable. It is a one piece.

The centre part of the airdam on my Rudemaster was $20 from GM.......4"

The outers are $15.....and can be molded somewhat.
Author:  Sam Powell [ Sun Jul 11, 2010 4:32 am ]
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Quote:
Early 80s Chev 4x4 trucks have a great 6" airdam that is very durable. It is a one piece.

The centre part of the airdam on my Rudemaster was $20 from GM.......4"

The outers are $15.....and can be molded somewhat.
I love everypart of this post, especially the Rudemaster.

Sam
Author:  nuttyprof [ Sun Jul 11, 2010 3:54 pm ]
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I have thought about using a plastic bumper cover from a newer car as a starting point. Just find a profile you like and cut it to the height you want. They should be pretty tough and if you can find one that was replaced for damage in a part you wont be using you might get it for free!


Dave
Author:  Sam Powell [ Mon Jul 12, 2010 4:25 pm ]
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Here is the challenge, material wise: it is finding a material that you can fasten for fabrication purposes that is flexible enough to bend when pushed on by outside forces, and yet tough enough to hold a screw or rivet. On the Ford a part I have adapted, they used speed nuts on the plastic part to minimize the tearing force a screw alone would produce.

So here is the specific I am looking for. What I want is basically an L girder shape in a flexible plastic, about 1/16" thick. I would like it to be maybe 3" high on one leg, and an inch or inch and a half on the other. If I could find that, I could fab the underneath fairing out of plastic and fasten it to this material with the push type fasteners that are so widely used these days.

I have searched the internet for this but am too ignorant of the technical names of the various plastics to know what I am looking at. It is kind of like the supreme court judge said, "You know it when you see it". :wink:

Sam
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