1998 Honda Civic DX - Homebrew Air Dam

[Hog F150]

I bought a '98 civic dx a few weeks ago. Not exactly the car I was looking for (waiting on a VX), but this one is almost rust free, and the price was OK.

I installed my Ultra Gauge on the car, and without any calibrations, it was reading right around 40mpg at 55mph. This probably on the high side, but we'll see. My first full tank of gas is almost gone, so I'll check the numbers soon.

Yesterday, I installed my custom built air dam. I bought 5 inch "contractor grade" edging for $16 at the local Home Depot. There really isn't much to bolt an air dam to under this car. There are 5 bolts that hold the plastic bumper to the frame. I used 3 of these to hold my plywood to the underside of the car. Step one was to make a template of the underside of the bumper. I used some old blue insulation I had in my shop to do this. My daughter helped me hold the foam board under the car while I cut it using a razor blade. Then, I traced the shape on to a 1/2 inch piece of plywood, and cut it out using a jig saw. I then reinforced the edge with more plywood. The next step was to screw the edging onto the plywood. This was fairly easy, with the help of my youngest son. The trickiest part was trying to find the holes to secure the plywood to the frame. I little messing around, and I got 'em in. I also cut out the slots for the tow hooks so the plywood would lay snug under the car. I figure this plywood frame would be nice to attach a belly pan to in the future if I ever decide to do it. I drove the car down the road after I installed the dam, and sure enough, I scraped it on a few spots on my old town road I live on. These are big bumps in the road, so I wasn't surprised it scraped.

So, going 55mph on a flat road, the gauge was hovering around 44mpg. I picked up .4mpg also in a 10 mile trip. I believe it was worth the effort.

Removal will be a snap. Undo 3 bolts, it's off.

[whatmaycome14]

Looks good. I would love to see what kind of difference it ACTUALLY makes. I mean this to strongly suggest that you ABA test. If it's only 3 bolts, it should be easy!

I for one would be really curious to see how similar the results would be with this:

Front Air Dam ABA test results: 7.49% increase in MPG at 60 mph (2003 Honda Civic DX) - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com

[MetroMPG]

Thanks for the write-up & photos.

There seems to be a little air dam modding frenzy going on these days! With the one on Daox's Metro and me copying it somewhat for my Firefly.

I've only driven the car on the highway once since sticking it on, and the results were better than normal, but I can't be sure if that's me or the air dam. I'm definitely considering an A-B-A test out of curiosity.

[NickelB NL]

Looks nice and solid. But it looks like a frenzy, it got me thinking of doing a airdam so hard these days that i was around town searcing for some right materials. But cant find any. Only lawn edgeing i can find is soms hard waving thin plastic. So the searcing continues.

[Xist]

Heh, I am lazy, but I probably have one of the biggest air dams on here, therefore the world! It extends all of the way up to the bumper, covering the lower grill!

I have so many things that I need to do with it, though.

[MetroMPG]

NickelB: even a couple of layers of coroplast should work if you can get that.

[Hog F150]

Originally Posted by whatmaycome14

Looks good. I would love to see what kind of difference it ACTUALLY makes. I mean this to strongly suggest that you ABA test. If it's only 3 bolts, it should be easy!

ABA requires cruise control, doesn't it? I don't have cruise, so I'm off the hook!

[Daox]

Looks good!

[Joris]

Originally Posted by Hog F150

ABA requires cruise control, doesn't it? I don't have cruise, so I'm off the hook!

Coast down testing does not

[Hog F150]

First tank is gone, 405 miles with 9.495 gallons. Very pleased with this result, only to get better down the road. Ultra gauge was off a bit, said I was averaging 39.7mpg. Calibrated the mpg's for more accurate reading ahead.

One thing I noticed that doesn't make a lot of sense regarding mpg's. In two separate trips to the ball diamond, I had 4 people in the car with me. On both occasions, my average mpg's went up, not down with heavier load. I don't EOC, but I do coast a lot in neutral with the engine on. I'm assuming the added weight will make me coast farther, and thus the increase in fuel economy. There must be a sweet spot (weight wise) for the best economy, not necessarily the lightest load possible.