I've been driving my car for a few weeks now with the grill completely blocked using two pieces of foam pipe insulation. This was a temporary measure, so I could monitor the engine temperature to see if this would be detrimental. After finding that it was fine (the temperature never got above 91°C, same as before blocking it), I decided to do a more aerodynamic grill block, including the fog light pockets too.
I knew I wanted use the KwicKan material, but I pondered for quite a while on how to cut it to exactly the right shape. I finally arrived at the idea of constructing a template piece by piece, by taping narrow strips of thin cardboard across the grill, and marking the edges of each piece with where the edges of the template should be. A few pictures are worth a thousand words:
I used progressively narrower strips as the curvature got sharper, and at the end, I fitted in small pieces to match the curve:
Before removing the template from the car, I applied clear packing tape over the whole thing to make sure none of the pieces could shift. I then connected the dots, using a spline for the very long nearly-straight curves, and a set of french curves near the ends:
Next I cut out the template, traced around it onto the KwicKan material (one each way), and cut them out:
To mount the grill blocks, I again used brackets made from 1/16" aluminum, this time in 3/4"x2" pieces. The pieces had to be bent to various angles ranging from 55° to 93°. To facilitate bending them, I made a poor man's bending brake out of a hinge, a piece of wood, and my bench vice:
The lower bracket for the fog light area needed to have its mounting surface curved slightly:
I attached all the brackets to the bumper cover using 3M body side moulding mounting tape, after thoroughly cleaning everything with hot water and then rubbing alcohol. My car has teeth:
My plan was to drill and thread holes in the brackets to take 10-32 bolts, but since I didn't have any handy, I drilled 3/32" holes and used stainless steel #4x1/2" self-tapping screws for now. I think I will order a bag of 10-32 black nylon bolts to replace these with eventually:
At the ends, I used a single #8x2" screw, through a 1-1/4" long aluminum spacer, screwed into the black fake grill at the back of the fog light recess:
Here is the completed grill cover. I left approximately 6" open in the middle, because this would be covered by the license plate:
And finally, here it's all done. The license plate has been installed over the opening, and the holes from the original license plate holder were plugged using the plugs from the bumper cover fasteners, painted to match the car, and press-fitted into the holes after drilling them out to 6.5mm:
I'm back to work next week, so we'll see how it all works out as far as fuel economy goes.
I have a few more mods in mind, most notably wheel covers. I was going to make these using the fabric and fiberglass resin over snap in wheel cover technique, but now I want to see if I can heat form the KwicKan material to make black plastic pizza-pan covers instead.