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AndrewJ 12-14-2007 10:12 PM

5th generation civic hatchback - improving aerodynamics
So in following the footsteps of the pioneer Basjoos before me, I too am setting out on the road of improving the aerodynamics of a 5th generation Honda Civic hatchback.

Goals are as follows:
1.) Improve aerodynamics from Cd: 0.32 to Cd: 0.26 or better (Honda Insight equivalent)
2.) Materials must be Weather, impact and wear resistant with a (projected) life of 5+ years of normal use.
3.) Overall design of components must be removable, with no permanent changes to the structure of the automobile.
4.) Aesthetic considerations play a role, notably in the S.W.M.B.O. test. (She Who Must Be Obeyed cannot object *too* strenuously to the aesthetics of the modifications).

In pursuit of these goals I plan to implement the following modifications, in roughly this order:
1.) Rear wheel fairings (not the most effective, I know, but the easiest, and most forgiving)
2.)Front wheel fairings
3.)Partial front belly pan
4.)Fiberglas front nose/splitter

And now for a quickly photochopped picture of phases 1-4

Now, to kick-off my little project I acquired a full sheet of 4-5mm (?) thick peice of white one-sided-grained ABS plastic. This actually took about a solid month of trying to track down my local plastics supplier. But today I actually found him and for a mere $75 took home a sheet of awesome white ABS.

ABS seems to me to be the ideal material for making fairings and such because of it's malleability under heat and because it can be "welded" with the right equipment. Luckily my local Harbor Freight store has the welding kit if I ever feel spendy, and they had a heat-gun on sale for $9.99 last week which I fortuitously saw fit to pick up even though I had no ABS at the time.

AndrewJ 12-14-2007 10:15 PM

So I got the first of my aluminum supports for the rear wheel fairings attached to the car tonight. It got dark before I could get the second side on though. Oh well, I have a little time tomorrow. So here's some lovely crappy pics.

Here's the horizontal support brace installed; it's pretty sturdy.

On the back side I've attached it with an "extruded U-clip" to the rear bumper.
In the front I basically attached it with a larger, stainless-steel version of your standard drywall anchor. I unknowingly chose to drill into the body where I can't get behind the sheet metal to get a nut on the bolt. So that's where the big drywall anchors come in.
After having it on the car, I've decided that I'm going to try to find a hinge to put on the front part of it tomorrow. A hinge will greatly facilitate tire removal if (when) I get a flat.

The only other thing I need is a much smaller bracket above the tire to hold up the top of the fairing.

So far, I have spent about $8 on the 1"x 1/8" aluminum bar stock and about $15 on various stainless steel hardware, that seems like a lot for hardware, but it is stainless steel, and I have changed my mind about fasteners about 3-4 times now...:rolleyes:

AndrewJ 12-14-2007 10:16 PM

ok, I got all the brackets for the rear fairings installed. There is one horizontal bar running the length of the wheel well opening on the bottom and a small tab on the top of the wheel well opening approximately between the 11o'clock and 12 o'clock position (from the drivers side)

Now I just have some template-finessing to do. The initial templates I made for the rear fairings are a little off. I made them before I had the aluminum brackets made or installed, so they're a bit off.

AndrewJ 12-14-2007 10:17 PM

So I got the rear fairings finished up and installed. They need a little bit more coaxing with the heat gun in places. That and the heads of the bolts and the washers need a good coat of white paint.

For all those interested in using ABS in the future please note that it will discolor if you heat it up too much with the heat gun, so heat up the back side of the piece so you wont see the discoloration when it is installed.

AndrewJ 12-14-2007 10:34 PM

So, first off, I'd like to amend my initial "goals" section.

I've decided that I probably won't be converting Harold to an EV. I just don't know what my driving needs will be in the future, and for any foreseeable EV-type range I'd rather just ride my bike.

So, since I probably wont be keeping this car long-term (and it's not worth much anyway) more "permanent" changes are quite acceptable.

So that brings us to today's installment: Airdam Mania!

I've had a crappy cardboard/white-duct-tape grill block on the car for a while now. It's been great, but I decided to make a more permanent combination of grill-block and airdam.

Sure, this will increase the CdA of my car, but it will also take care of two (or three) nasty areas of aerodynamic drag, thereby decreasing my Cd.

Alright, here's a pic of good ol' Harold with the temporary grill block:

I went ahead and cut a 82" x 17" strip out of my ABS sheet and grabbed a screwdriver and a few self-tapping screws. Here's what I came up with.

I've got a bit of driving to do this weekend for work, so I'll have to see how this new airdam effects my speed on a few "calibrated" hills on my drive.

MetroMPG 12-14-2007 10:49 PM

Awesome. Great to see another set of wheel skirts join the fleet.

I have a theory that rear wheel skirts help more on cars where the back wheels are set close to the back of the car - meaning, there's not enough bumper cover behind them where flow can reattach before turning into wake. Typically that means small cars.

Anyway, very cool work & looking forward to watching the progres.


Housekeeping question: some of the photo sizes (big) are wreaking havoc in my browser - do you have an intermediate size option you can link to @ photobucket?

AndrewJ 12-14-2007 11:10 PM

images downsized sir. :)

igo 12-14-2007 11:36 PM

Good work on the wheel skirts. That air dam is huge. I would be worried about scraping going around bends fast or hitting bumps.

Lazarus 12-14-2007 11:50 PM

Outstanding. I llike the skirt brackets. Are you planning on a mirror delete? Those are huge. Very nice work indeed.

XFi 12-15-2007 10:16 AM

Looks Great! Glad to see you still making aerodynamic advancements with Harold. (and continuing your GS thread here ;)). I am definately interested if the front spoiler affects your MPG or coasting at all. I am thinking about something like that for the UnNamed Wagon. To be honest, my feeble mind didn't even make the connection to 'ajohnmeyer' until I saw these pics.:o

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