Now the upper grill is blocked, and I have a barrier to keep the cooling inlet from spilling under the bumper and contributing to the underbody flow instead of cooling the engine (I decided ducting is too much trouble). Also I plugged a large gap above the bumper. (Too bad I couldn't find the backer rod in black though.)
I'm fairly pleased with the forward slope. I'm sure it could be even steeper before being optimal, but it looks effective to me. I'll probably do my road trip just like this.
My defunct bullnose contributed pre-painted coroplast that I wrapped around the upper grill and screwed in place on the top and bottom. (The plastic stock grill pops off for easy modding.)
Also, here is an upward shot so you can get an idea what the airflow might look like underneath. (Despite how it appears, the air dam is actually the lowest point.)
There are still a few items on my todo for the air dam, but I think these are less important:
- Add half-tubing at the bottom lip for smoother flow underneath.
- Add sides to the barrier to better separate cooling flow from underbody flow.
- Paint most of it black.