Kammback Angle Okay?

[blowncopcar]

Does this angle look correct? Its my 97 G10 Metro. I measured it thoroughly while I worked on it and the most angle it has is 15* degrees... But to me it looks a little too steep but I keep reading that 15* is what you need and i measured it with the right tool so i know its correct.
So does this look okay at the moment? I plan to extend it in a few months so I want to make sure my start on it is correct. Of course Ive had an increase in mpg since making it months ago but I wanna know if it could be better.
BTW__ This isnt completely finished yet I still have the final sanding and paint left but not til after I finish it so dont rag me about the finish yet lol
Thanks guys.

[Xist]

Originally Posted by blowncopcar

Does this angle look correct? Its my 97 G10 Metro. I measured it thoroughly while I worked on it and the most angle it has is 15* degrees... But to me it looks a little too steep but I keep reading that 15* is what you need and i measured it with the right tool so i know its correct.
So does this look okay at the moment? I plan to extend it in a few months so I want to make sure my start on it is correct. Of course Ive had an increase in mpg since making it months ago but I wanna know if it could be better.
BTW__ This isnt completely finished yet I still have the final sanding and paint left but not til after I finish it so dont rag me about the finish yet lol
Thanks guys.

It is not so much the angle as the curve. Please take a picture of the entire car, including the tires touching the ground. We can level the image and put it on the template for you.

[mcrews]

side picture

[blowncopcar]

Originally Posted by Xist

It is not so much the angle as the curve. Please take a picture of the entire car, including the tires touching the ground. We can level the image and put it on the template for you.

Thanks i will try to get a picture on here tommorow night.... but I used an angle level to measure it so i figured it would be accurate no matter what height or angle the car was...

[Xist]

This is one that I did off of someone's car on here:



As I wrote, it is a gradual curve, and according to the template, it looks like it would take more than three feet from the top of the rear window for the curve to reach 15°.

Please take a picture of the side of your entire car and we will put it in the template for you.

[ChazInMT]

Here ya go, I found a pic online for ya.

Put a little Kamm on there like I'd make it, and it is at 10° overall, it is curved, so it is a bit shallower at the top.

The over all shape is below the curve, but I think this helps based on what I see several automakers doing. Most notably on the Honda Fit.

I think it is still not too steep so flow remains attached, but it closes the angle on the wake reducing its size.

If you make it flat, you'll want to be more like 7° because the 10° transition will cause a flow separation that won't be made up, and it will negate any real benefit of building a Kamm.....other than a sun shield for the hatch area .

The Kamm you have now appears too steep in my estimation.




Bigger Image of the same pic.

[NeilBlanchard]

It might be a little too steep, but only tuft testing will tell for sure.

[mikeyjd]

Originally Posted by NeilBlanchard

It might be a little too steep, but only tuft testing will tell for sure.

^

[blowncopcar]

Here's a picture. yet now from that last picture I am beginning to think also that it is a bit to steep.... I prolly need to raise it up to 10 or 11 degrees then slope it down from there.... I was going to extend it son anyway so I can just do it all at once. Sorry the pic is cropped so much I had to do that to get the file small enough.

[ChazInMT]

Boom, w/ template to look at.