Aero-Modding the 4Runner

[jeff88]

Thanks for the help Xist.

So I went back to the template to play with it some more and noticed two things:

1. If I actually read the instructions, I will see how I am supposed to line up the template. The only thing I don't understand is: "Ground planes of both the template and the car are aligned." So the lowest point of the truck, minus the wheels and the lowest point of the template should align?

2. I am about 90% sure that the parking spot is not level (I've been parking there since I was in elementary school, so just from memory...), so I will retake the pic on a level platform and also make sure that my camera is *relatively* level. Or at least make sure that the camera matches the slope of the truck. I believe the rear end actually has a stock sag to it, so for this project, that might actually be helpful.

I'll take the truck to school today and look really strange with my level, checking the ground slope. Maybe I'll do it in the Environmental Studies parking lot, at least there I have a decent excuse.

Just an FYI, this is what happens when you take the steps off: Rusty Running Boards

[Xist]

I am always happy to help! That was atrocious rust!

1. Actually, I think that the ground surface and the bottom of the image should be parallel. I always adjust the window so that one of the wheels is touching the bottom of the screen, and then rotate until both are.

2. Yes, I think that the relationship between the camera and the car is actually more important than how level the ground is, within reason.

I'll take the truck to school today and look really strange with my level, checking the ground slope. Maybe I'll do it in the Environmental Studies parking lot, at least there I have a decent excuse.

Just borrow a lab coat!

[jeff88]

OK, well my school parking lot wasn't level, not even close (I really did bring my level and check ), but the elementary school parking lot across the street from my house is, for all intents and purposes, perfectly level. So I redid the pic and template.

I did the template for the stock truck:


I also did the template with an estimated height of a roof rack:


I also realized today that I don't necessarily have to do a roof rack to have something to attach the kammback to. The truck comes with some sort of wind fairing, spoiler thing, which I can take off and attach a kammback.


Here is a birds eye which shows the screw points. I could take it all off or just take off the fairing and leave the mounts. I can then attach a cross bar to those mounts and attach the kamm to the cross bar.


I also measured the height of the truck, since it was on level ground. It is really hard to tell with the template, but if you look closely, there is a slight slope front to back. I measured the front of the roof at the windshield, the midpoint right in front of the roof rail and the rear just after the roof rail.
Front: 67" tall
Mid: 68" tall
Rear: 67.5" tall

[Xist]

Please compare the bottom of your tires to the bottom of the template:


Those attachment points look good, though.

[jeff88]

Xist, what do you mean compare the tires to the template? Are you talking about the lack of levelness between the front and rear tire? I can see that the bottom of the front tire and the template match up, whereas the rear wheel is lower than the template. I'll have to check to see if I have a photo program that can rotate it a matter of degrees, not 90* or 180* only.

I'm kinda excited about doing the kamm with the spoiler attachments. I'm thinking about using an aluminum strip as the main mount. I am considering using a plastic strip from TAP plastics as well. Anybody have any suggestions?

[Xist]

Originally Posted by jeff88

Xist, what do you mean compare the tires to the template? Are you talking about the lack of levelness between the front and rear tire? I can see that the bottom of the front tire and the template match up, whereas the rear wheel is lower than the template. I'll have to check to see if I have a photo program that can rotate it a matter of degrees, not 90* or 180* only.

I'm kinda excited about doing the kamm with the spoiler attachments. I'm thinking about using an aluminum strip as the main mount. I am considering using a plastic strip from TAP plastics as well. Anybody have any suggestions?

I use Gimp, it is free, although I use Paint more. The Win8 Paint has more features, just like WordPad, but neither can take the place of real programs.

However, it would be faster for you to post the original picture and I will adjust it for you.

At least until I close Gimp!

For some reason, it seems to take a full minute to load! This is a nice, fast, and new computer, too!

[jeff88]

So I forgot that I had installed a photo editing program on my laptop. I was able to rotate the pic by .01! (I have no clue what .01 is -pixels, percent, whatever- but hey it worked!) So the wheels are aligned with the bottom of the template and it looks like this:



Here is the pic with the wheels aligned and an imaginary roof basket, to give an idea of what I would need to do and what it would look like:


I also included the base pic (not aligned yet):


I also included the base pic as an attachment in case it helps!

[Xist]

Jeff, those look very good!

[jeff88]

So I removed my crossbars almost 3 weeks ago. At the time I was averaging 20MPG at the pump. The next tank, I got 18.4MPG. WTF it went down!?!? Second tank after it was 18.8, again way down. Ok something is wrong, maybe I need to check some generic maintenance stuff. Didn't get to it. Now at my third fill up after the cross bar delete, I had a whopping 21.5MPG!!!

So now, I'm trying to figure out #1 is there something wrong, or did my driving style change for a couple of tanks (city vs. hwy, aggressive vs. conservative, ambient temp.). And #2 how to determine the increase from the delete. Math would dictate a 1.5MPG increase (21.5 current vs. 20 avg.), but it's tough to say. I'm going to leave them off for another tank or two, then do another 'A' test if I feel it's necessary. (If I continue to get 21ish tanks, I'll probably just go with it.)

[Xist]

I never did A-B-A with my crossbars, I just do not think there would be a measurable difference. Whatever it is worth, they are shaped like an airfoil.