Grill block on a Silverado
 

Well, some might argue I'm polishing a turd, but I'm going to try anyways. First step is a partial grill block on my 2003 Silverado. The entire grill just snaps in place, so it was real easy to pull off. Since it wouldn't pass the wife test otherwise, I went for the stealth block behind the grill. I'm not sure how much support is needed (if any) but I wanted to reinforce the attachment points a little, so I used some small, flat steel plates I had laying around.

http://www.schoolforwinners.com/~dar...illBlock03.JPG
http://www.schoolforwinners.com/~dar...illBlock04.JPG

No results yet, and I don't have the time to do rigorous A-B-A testing, but I keep close tabs on fuel usage and driving habits so I should be able to see what, if any difference, it makes.

Mike

It'll warm up faster and therein lies the bulk of any gain.

Well, if that's the only gain, it will be worth the effort. It really wasn't hard to install.

Mike

Clean installation. Added to the EM project library.

Probably don't have to say this, but with a vehicle that uses a lot of fuel, changes to "MPG" from mods are going to be relatively small, numerically.

I often see people say things like "only a 1 mpg gain? It's not worth it!". Which of course isn't true with a thirsty vehicle if you look at the volume of fuel saved, rather than MPG figures. (Not implying you'll see a 1 mpg gain.)

Weren't we arguing a few months ago about the effectiveness of a rear grill block, with me saying it's not any better than the resistance presented by the drag from the radiator and engine bay?

I don't remember that; and that doesn't sound correct either.

I decided that any gains are going to be tough to see (0.5-1 mpg) and could be written off as being within the usual fluctuations in mpg, so I went ahead and did the partial belly pan as well since I had some time (a rare occurance).

The belly pan was a lot more effort, but I think it came out nice. I'll get pics up in the next couple days.

I took a longer trip over the long weekend. Fuel mileage wasn't what I was hoping for, but I was carrying a decent load and went through four steep mountain passes, so it's hard to say if my mods helped or not.

block
 

The grill block was one of the recommendations listed by Rich Taylor of GMC truck division for MPG increase with Popular Science' Sierra.
If you can find the Phil Knox aerodynamic photos album,there is a copy of the graphic showing aero mods recommended for the pickup.

http://ecomodder.com/forum/member-ae...mendations.jpg

Found it, thanks Phil.

It doesn't quantify each mod individually, so it's hard to say how much it affects mileage. My next step is blocking the area between the frame and the body between the wheels (#3 in that image).

I want to get rid of the canopy and get a tonneau cover instead, but that's a tough sell with my wife. She finds the canopy too useful even though I find that it gets in the way.

Before adding belly pan:
http://schoolforwinners.com/~darcane...ellyPan_01.JPG

Metal framework that it attaches to:
http://schoolforwinners.com/~darcane...ellyPan_02.JPG

Belly pan cut out:
http://schoolforwinners.com/~darcane...ellyPan_04.JPG

..and attached:
http://schoolforwinners.com/~darcane...ellyPan_05.JPG

I've since added another four screws to hold it more firmly in place. It is fastened with 1/4-20 screws, fender washers, and spring nuts.

I'd like to find a clean way to cover the tow hook holes as well, but I haven't figured that one out. I want to be able to clip a cover in place and be able to remove without reaching around the backside of the bumper.

-Mike