Aero trunk lid project

[Pendragon]

Originally Posted by California98Civic

<snip>
1% FE from the raised lid would be 2mpg at my base 50mpg freeway norm. An extra 24 miles per tank is almost 2 bucks at current prices. That would feel pretty good. <snip> (YAY!)

My calculator might be off, but 1% of 50 mpg on it comes out a 0.5 mpg (half a mile per gallon) which is still a worthwhile improvement. I would not be surprised if you are able to better the 1% improvement.

[California98Civic]

Originally Posted by Pendragon

My calculator might be off, but 1% of 50 mpg on it comes out a 0.5 mpg (half a mile per gallon) which is still a worthwhile improvement. I would not be surprised if you are able to better the 1% improvement.

Ugh. I'm an idiot. You are right of course.

[California98Civic]

Originally Posted by Pendragon

The trunk lid on California98Civic's car is in too nice of condition to start drilling holes and such for experimentation. I have not check prices, but if one can be found for a reasonable amount.... A hail damaged one would be perfect. "Nobody wants one of those" = cheap.

I have a junkyard I have been meaning to go to to see what of a longish list I might find with now and the future in mind. I'll add this to the list. What the hell. Could be useful in lots of ways...

Originally Posted by Pendragon

[Edit] P.S. Yes, most cars wrecks are crunched on the front end. Have you ever looked for a hood for a Z-Car?

Not many people back-up into stuff at 50mph!

[wyatt]

I just use a plain old carpet knife (box cutter, utility knife) to cut through the inside layer of the cut, then bend on it. If you read through the tread about my SedanKamm, I basically say that I use a straight edge to cut along, then use the straight edge to bend along. It works well.
A table saw could be used easily enough, but coroplast is so light weight, that you will find it's really overkill.

[backyard engineer]

Hey California, was thinking about that kamm addition what if you hinged it on the rear attachment point with some kind of release mechanism up front. You'd release the front tilt it back while holding it with one hand open the trunk with the other? or how about a slide mechanism, with release slide back and open the trunk? just some cheap food for thought.

[Pendragon]

Originally Posted by California98Civic

Ugh. I'm an idiot. You are right of course.

I disagree. You are doing some interesting things. Keep up the good work!

Cheers

[Cd]

Just my guess, but I would say that adding a couple of inches in height to the trunk isn't going to do anything at all. Like Wyatt was saying, it probably would be more beneficial to go higher and farther out.
Sorry for not giving you a illustration of what i meant by the tufted spine that you could use on the car.
It seems like you understood what i meant though.
BTW, If you left the back end of the test section ( the raised trunk or 'boot' ) open - just below the flat test section and the actual trunk, you could raise it as high as you wanted and still see behind you ( it would block a small section of the rear glass, much like the rear view from a Prius.
It might even be beneficial to have it open like that, since it would create a small vacuum in that area just at the edge.

EDIT : I see that you already have the edge open. If you went higher with it, I would think it wouldn't obstruct much of the rear view.

[brucepick]

Originally Posted by Cd

.... I see that you already have the edge open. If you went higher with it, I would think it wouldn't obstruct much of the rear view.

Like in this drawing. The 2 green lines begin (at left) at 2 guesses of where the mirror is. They end where the spoiler has to be, if it is to meet the template and be even with rear bumper's vertical line. As long as the spoiler is located along the "correct" green line, visibility out the back should be pretty good.

Ignore the two lower spoiler lines; they are likely to get you pulled over due to extending too far back...

[Frank Lee]

I've wanted to try something like the lower lines on a Tempo; if I get pulled over I'll tell 'em that one time I contacted law enforcement to see at what point when something is sticking out the back do I need to put an orange flag on it? They said three feet. So if I ever do that project I'd go out <3' and plead innocent.

[California98Civic]

Originally Posted by Cd

BTW, If you left the back end of the test section ( the raised trunk or 'boot' ) open - just below the flat test section and the actual trunk, you could raise it as high as you wanted and still see behind you ( it would block a small section of the rear glass, much like the rear view from a Prius.
It might even be beneficial to have it open like that, since it would create a small vacuum in that area just at the edge.

EDIT : I see that you already have the edge open. If you went higher with it, I would think it wouldn't obstruct much of the rear view.

Interesting. Thanks. How might the vacuum help? I ask because I have this friend who finds this trunk lid idea amusing. We laugh about it and then I try it again. He has aero design experience. Beside the fact that he is probably correct about my lid (pun intended), he thinks that the trailing edge, with the open back, does more harm than good. He seems to think it adds to the low pressure circulation zone behind the car. What do you think? I begin to think that without a significantly downward angle to the spoiler, he might be correct. Wouldn't a downward spoiler reduce the wake by taking the attached flow I know is coming down the window and sending it into the wake area? Wouldn't that reduce the wake area? Does that make sense?

EDIT: added image of what I mean. Would need to be clear to avoid visibility loss. Probably could be made to avoid trunk loss.