Eternabond tape should last as long as the car...but it's a bit pricey.

Jay, for the grill block my parents used heavy fabric and snaps (like jeans have) to attach it. Snaps all around the grill (was a '85 suburban) and a zipper down the middle for easy opening to cool it. It did run quite hot when it was fully closed unless it was winter, so I'd be hesitant to put a full sheet of plexi across the whole (90%) grill.
I strongly recommend this, it worked flawlessly. I could ask my parents for an old pic (it's gone to the twisted frame heaven now) if you'd like.

Holycow, the engine may handle the 137* heat while heavy towing, but the transmission sure wouldn't! But that's another issue to worry about later.

I know what you're talking about with the fabric. They do that with big trucks. I'm trying to go for a stealth look though. How about a sliding panel along the bottom that I can just adjust with a long screwdriver through the grille at the change of the seasons?

-Jay

I just had a thought... I could make a block out of smoke colored plexi and mount it to the front of the grille... It could look like a really cool custom treatment. I think I remember enough about working with plexi from shop class 25 years ago that I can make a professional looking result. The only problem with that is that I don't wash the truck often, and it would probably look bad after a while with all sorts of smooshed insects splattered on it.

-Jay

holy cow,

I use the cut off wheel. it more melts through it but I figure I can control that better than the other bits for the dremel. I usually make one pass just to get it started and usually it just makes a melted groove. I then go over it again in the same grove to clean it out taking out half to two thirds of the thickness out of it. I then crack it out. kind of like scoring glass and breaking it to size. I then take sand paper and even off the edge of it.

A long process but the end product looks pretty good. I did a grill block for my wife and cut out a hole in the middle of it for the honda symbol. that was a bear. also with the cutoff wheel, you can use it sideways and take off a little excess material. kind of fine tune the opening.

DEFINITELY USE SAFETY GLASSES!!!!!! mess flies everywhere.

Great concept with the air dam. I think most trucks would benefit from a similar extension that goes as low as the lowest point of the front undercarriage.

As for the grille block, consider black ABS. It's very durable and is less obvious when it is a bit bug splattered with the rough side facing out. Here's the one I made and I think it looks pretty decent: https://www.gassavers.org/garage/view/347

This extends lower than the vehicle's ground clearance. As it is right now it clears curbs and those concrete barriers you find in parking spaces by about 2 inches, so I shouldn't screw it up on a speedbump or anything like that. Again SG reported 11 MPG on my way into work today, but it was a rather cool morning here in the DC area, and it stayed in open loop longer than it has the past week. I still think that SG's variance is off again. I hope that they respond to my tech support email soon. I think once we get SG to properly recognize DFCO this whole crap of my variance swinging wildly with each tank will stop.

As far as the grille block goes, ideally I want a large sheet of black plastic. The only other way I think I can get some cheap black plastic is to buy a cheap black plastic trash can, cut out the bottom, and cut the top lip off. Slice down the side and then roll it out. A little coaxing from a heat gun should convince it to assume a flat shape.

What type of gains did the grille block get you on your truck?

-Jay

Unfortunately the only quantifiable improvement we were able to determine was faster warmup. I'm sure that translated to improved economy, but we just didn't have the A-B-A data to back it up in any way aside from one test run I did on the highway which was inconclusive.

If you want something that looks professional, one option for those using trucks is to get a "cold front". Basically they are snap in plastic pieces that block the grill and can snap back out. They come in black, black with small holes (so they don't block completely) and chrome. With a little bit of luck you can probably find used ones pretty cheap.

They are designed for winter use, and are quite popular up here in the frozen north. The nice thing about them is they take seconds to install and remove, and the look pretty good installed.

https://products.armordeck.us/lund/pl...rille-inserts/

I have these for my truck and have been using them every winter for years (to improve warmup times).

Mr_C

:thumbup: The piece I have from a skylight is smoke colored, with tint film.

Another idea, if you don't mind spending a little money, is one of the aftermarket cosmetic grille inserts available for pickups.
https://www.jcwhitney.com/wcsstore/jc...4856G_TH_1.jpg
https://www.jcwhitney.com/wcsstore/jc...0d9485dc616856

I've seen some that look like they only have 10% of the stock opening.

Looks like they're available for some popular car models too...
https://www.jcwhitney.com/Car-Grilles/600002181.jcw