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Old 12-30-2012, 02:54 PM   #4 (permalink)
Master EcoModder
Join Date: Oct 2012
Location: Carson City, Nevada
Posts: 612

Jimmy - '00 GMC Jimmy SLT
90 day: 21.18 mpg (US)

The White Gnat - '99 Suzuki Swift
Team Suzuki
90 day: 51.87 mpg (US)
Thanks: 240
Thanked 109 Times in 87 Posts
It looks like you've got the same front end design as my 2000 Jimmy. (see attached thumbnail - click on it to enlarge) If you don't care anything about "stealth", you could do what I intend to.... attach the bottom of the grille block at the little "lip" in the bumper (a "natural shelf"), and the top to the very top of the grille chrome. This makes a very nice slope back that really "rounds off" the front end nicely. Then I continued the block over the front of the headlights with clear plexiglass. I had a couple of pieces 12" by 24" and they fit well enough I didn't even need to trim them. (although some trimming would help). Then I used 2" wide clear packing tape to go around the sides to the front of the fender. With the exception of the middle piece of cardboard & duct tape, it looked a lot better than I expected it to.

Similarly, for the 2 holes in the lower bumper (where my tow hooks stuck through), there is also a "lip" of sorts around the edges that I found perfect to fit the blocks to. Now, cardboard and grey duct tape isn't exactly the most beautiful way to do it, but either clear pieces of plexiglass so the hole still "shows", or a painted piece of something (fiberglass? - coroplast?) to either match the bumper color or maybe flat black to add a contrast would probably look better. Then I'm thinking about "glueing" it on with silicone sealant under the edges instead of the ugly duct tape.

Now for the air dam question, my understanding is keeping as much air as possible from going under the car is most critical for high speed stability (as in a race car). But for lower speeds (say, 70 and under), streamlining the front by rounding it off without adding more frontal area would be better. So for my car, instead of bringing an air dam straight down to some point the same height as the lowest hanging stuff underneath, I plan to make a "belly pan transistion" from the bottom of the front bumper to some place under the engine/skid plate. This will actually slope down as it goes back, but at the speeds I drive, I'm not worried about "lift". - LOL

If some other aero guru would like to chime in and either verify my theory or correct me, I'd welcome it.

EDIT: The grille/headlight/tow hook covers as shown in the thumbnail yielded 1.45 mpg increase in careful A-B-A testing with a ScanGauge. However, it sealed off the air to the radiator so well, I had to cut a 6" diameter hole in it to prevent overheating.
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ECONORAM (12-30-2012), SCNTN (12-30-2012)