I had considered putting my block on the outside, and cutting out the letters, but then I figured I would spend forever doing it because I'd want it to look perfect. I don't think there's much aero difference between a front and back grille block. When blocking from behind the void will fillup with high pressure air, and effectively make it "flush" with the rest of the body. That's why I'm not too concerned with mine.
I don't buy the "void will fill up with air" theory. It's essentially a big parachute facing forward. Even if it fills up, it's at least bound to cause unnecessary turbulence.
We'll see if this lasts long enough to get FE numbers. It will be tough to compare, though, since I don't have cold-weather FE results from the temporary radiator block (which itself is not the same as a behind grille block like you have).
First off that's nicely done, for a backyard job this would be acceptable
in terms of looks, I could tolerate being seen in that.
Now that's just me.
But I did want to add, and towing a trailer and considerable amount of weight may
have something to do with it...
But aerodynamic modifications on my D-2500 did little, if anything.
Because on my truck, most of the power from the engine goes into pulling the weight.
It just doesn't seem to make a difference, whether I'm doing 35 or 60, the engine is working to get some solid matter down the road and it seems the aerodynamic drag is a puny annoyance at worst.
So cars definitely come out ahead here.
A FE gauge should be standard equipment in every vehicle.
Depending on what type of trailer you have and what type of driving you do, I guess rolling resistance from tires and wheel bearings could be a significant loss.
So, towing a box trailer or camper on the highway, aerodynamic drag is by far the biggest loss.
If you have to do lots of stop and go towing, then weight becomes the biggest issue. When towing you can't fly around turns, and you can't avoid braking for some things that you could when not towing, though you can avoid braking for predictable stops even better with more patience from drivers behind you (or less ability to see them ).
I wonder how Pulse&Glide is affected by towing? On level land, depending on aerodynamic loss, the cycles could get much longer with all that extra ballast, and the pulse would be at maximum BSFC unless you have to downshift (or your automatic does it for you). OTOH, with large aerodynamic losses, P&G would probably become worthless.
I haven't towed my camper since before I got into hypermiling, I just haven't had the money to go anywhere.
I used door edge guards around my wheel well skirts on the CRX to give them a more finished look...and to fill in small imperfections from the tin snips. I used a radiant heater to make them pliable and the glue stickier before I placed them. Perhaps that may assist. They come in black.