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

Looks good:thumbup: Very clean look for the underside of a truck:thumbup:

I'd just make a cover from yer scrap coroplast and ziptie it to the hook. Yes...you'll have a little bit of the ziptie showing...but you'll git easy access to the hook if you need to. ;)

Darcane - your truck is 2wd right? Have you noticed any mileage improvements from your grill block/underpan?

I'm debating what steps to take on my Silverado. Just for fun I taped a big piece of cardboard over the grill and drove a route that I drive fairly often. I wasn't expecting much but got surprisingly better mileage.

I've driven this route 3 times in the last 2 days in similar conditions (11mph wind, ~32 degrees). The two trips without the grill block I got 17 mpg on the trip out and 19 on the trip back. After taping the cardboard on, I got 18 on the trip out and 20 on the way back!!

I'm going to have to do some true testing now to see if it is really having that much effect. Engine temp was unchanged - but the transmission temp jumped from around 130 to 175.

http://ecomodder.com/forum/attachmen...2&d=1259808359

Yeah, it's a 2wd but it's still too early to tell. I don't use a scangauge, so I only know by refilling my tank and making the calculations.

What are you doing to get the mileage you are getting? I drive with a light foot and keep my speed down and that gets me about 17.5mpg in my normal commuting (roughly 50/50 city/hwy but I run into a fair bit of stop and go). You seem to be getting better mileage than me in spite of a larger engine and 4wd.

I'd keep a close eye on your tranny temps. I believe the tranny cooler is the rusty thing on the driver's side in this pic:
http://schoolforwinners.com/~darcane...illBlock02.JPG
You may want to leave a slot in your grill block on that side to allow the tranny to cool off.

Mike

I haven't been doing anything too special. I've been trying to coast in neutral when possible, but I really don't do it that often.

I'm keeping an eye on the transmission temp, I think I'm fine as long as I stay under about 200. I think I will install my block in a similar fashion to yours, but in 4 pieces (in part because that is the size of my material :) ) That way I can remove as much as I need in the summer when the weather warms up or if I need to tow something heavy.

I've been very surprised and impressed with the economy of this beast. It has a few changes from earlier years (not sure when they were implemented in the history of silverados) like gap fillers btw the bed and the cab and an electric engine cooling fan.

I just bought it a couple of weeks ago and plan to do a few things and keep track of my mileage. All of my fillups thus far have been less than a tank just to see what the mileage has been like during some road trips and such.

I never saw better than 19mpg out of my last truck which was a Ford ranger 4.0 4x4 manual. So I'm thrilled to get better or equal to that!

Looking pretty good darcane. Here is a link to some of the work I've done on my Dodge RAM: http://ecomodder.com/forum/showthrea...ck-1228-3.html
Not a finished project yet, but I can get 24 mpg on the highway at 65 mph now...

Got gas log data anywhere?

I put this grill cover on my '09 Nissan Frontier for a couple days. Did a long road trip and have over 500 miles with it, but didn't notice any perceivable difference in mileage. Since this is my business truck I took it off, didn't want it looking too silly. Is it possible that it just wasn't helping at all?

http://gallery.me.com/goodoak/100022/IMG_0390/web.jpg

My original plan was to get some plexiglass and use dual-lock velcro to stick it on front of the grill. This would look good, and be easy to remove, but I bet it would cost over $100 to get the plexiglass cut to shape. Perhaps I'll try affixing this sheet inside behind the grill instead, but I can't imagine that would be easy to remove when its time to tow.

Darcane: what material did you use for your belly pan? I may also try blocking the gap between the frame and the rails.

ECONORAM: What did you use to fill the gap between your cab and your bed?

Well, the tank was still 2/3 full, but I decided to fill it up this morning just to get some preliminary numbers. No significant change in mileage. However, we've also had a cold snap (high 20°s instead of low 40°s on the last commuting fill up) this week and I've had to spend some time letting it warm up in the morning so I could see well enough to drive. I'll report more over the next couple months.

ECONORAM: I had previously seen your post and it gave me some ideas for mounting the belly pan. You may notice I'm using the same predrilled steel flat bar, which I used 1/4" spring nuts and screws to attach everything.

GoodOak: I used Corex sheet (essentially the same as Coroplast) for both panels. I picked up several sheets for about $16 per 4mm thick 4'x8' sheet from a local plastic supplier.

Any Update?
 

Darcane,
I was just wondering if you've noticed any improvement or if you have any updates. I have an Avalanche which I'm thinking of doing the same thing, I figure at the least it should reduce the warm up time. If I remember I'll hook up my programmer tomorrow and see how many miles it takes to get to full temp (it stops at 188*F).

Thanks,
Jeff

Too bad I don't have pix but for many years I ran a very nice pro-looking winter front on the F150- it was a foam pad on the outside of the grille, upholstered with seat vinyl.

It did NOTHING for fe except for the warm-up and heat retention benefits. I guess I should say it helped fe in that regard but did nothing measureable for aero.

So far, it's been inconclusive. I've been on vacation for two weeks so I haven't been doing my normal commuting route. And before that, we had significantly lower temps for a couple weeks (we actually set record lows a couple days). But so far, what I've been seeing doesn't look too promising.

I go back to work tomorrow and I'll be keeping an eye on my fuel economy.

Mike

I'm not sure if the avalanche has the same front end - but this is another option.

I found this online at a surplus store for $40 + shipping.

http://ecomodder.com/forum/attachmen...1&d=1262615647

This really tempts me to try a grill block on my Ram, but with it's stature (lifted etc) I really don't think it will help much at all.

But then I'll have to drive the truck on the highway... that's what the CAR is for. =)

Sorry, been off the boards for a bit. No, I just have it all written down in a notepad.

GoodOak, I went down to the local hardware store or Big Lots and bought foam weatherstripping. Had to layer it 3 or 4 thick in order to cover most of the gap... It is better to layer it before you stick it on the truck.

Jethro, your truck is already at an aero advantage over mine. The Gen2 Rams were much better aerodynamically. A grille block would still do you some good, I think. It helped me a lot in keeping the engine warmer last December on my 3,000 mile road trip...

I agree partly with ya Frank. I noticed on the Dodge RAM SRT10 it had a small grill block behind the left side, as well as other aero aids to get its Cd down to 0.44. My wife's Avenger has the entire top portion of the grill blocked, and it has a belly pan covering the entire engine bay. I suspect there are some aero improvements, but nothing earth shattering...

I just made one for my Dodge RAM out of a black plastic boot tray. I will try to get some pix over the weekend.

Ya might as well agree totally because... well, because. :)

Now that the cold snap is over, temps have gone back to about what I had back in October/November. Using the data from then as a baseline, my typical commuting mileage was about 17.5mpg.

With about the same temps and driving conditions I'm now getting 18.1mpg over the last two tanks for about a 3.5% gain.

I'd still say these are preliminary results, as that's only two (very large) tanks of fuel, but it at least looks like it is a positive gain from the grill block and belly pan.

Mike

Dodge RAM partial grill block
 

Okay, finally got a picture in daylight. I would cover more, but what you cannot see if about 1/4 of the passenger side (left as you look) is taken up by an intake scoop. About 1/4 of the right side is covered by a block behind the grill, so I do not have so much going into the radiator and a/c condenser. I have noticed going up hills and sitting in traffic the truck does warm up more, so this may end up getting trimmed or being a winter mod only...

I went out and purchased a grill block for my Silverado. The nice thing about it can be removed in about a minute when towing or in hot weather situations.



Winter/Summer Truck Grille Covers : Cabela's

Fia Front Grille Covers, Go Fia Winter Grill Cover, Truck Grille Covers

This thread caught my eye. I just did a 3K miles round trip driving, all interstate, mostly 70-75mph on my Toyota Sequoia. I blocked the lower grill using a thick cardboard, just for experiment. What is surprising, I was averaging 18-18.6 mpg with only 2 passengers on board. I have monitored the mpg closely in the last 4 yrs I owned her, and always does 16-17.5 mpg consistently on the highway, depending how many passengers and loads on board. I never get even close to 18, so this was a great surprise.

Is it possible that this simple mod can improve mpg this much? I am now considering a better solution than a cut up cardboard to make it looks better. Wife got to approve the look since it is actually her ride.

There are a lot of variables other than the vehicle itself to account for that affect mpg: driving habits, speed, temperature, wind, traffic. In order to determine what effect your aerodynamic mods have, you have to control all other variables.

Doing my best to control those, I am seeing about a 3.5% increase with my grill block and belly pan. Assuming a new max of 18.6mpg from your previous best of 17.5mpg, you are seeing about twice as much improvement. I suspect only part of it is from the grill block. Especially since the consensus seems to be that blocking the upper part of the grill is more effective than blocking the lower parts.

It still helps, but don't expect miracles.

Mike

Believe me, I was surprised seeing that much improvements. I was not expecting anything, no improvement at all. I had re-checked my numbers. Btw, I would not do any grill block as the weather gets warmer, and when I am towing.

Sorry for probably an obvious question, but what is the reason for "Especially since the consensus seems to be that blocking the upper part of the grill is more effective than blocking the lower parts." ?

I blocked the bottom grill on mine for a couple reason:
1. Transmission cooling radiator is behind the top grill, but not behind the bottom grill. I did not want to risk heating the tranny. Engine radiator is behind both bottom and top grill, so it still receive some air when I blocked the bottom grill.
2. I figure the bottom grill will probably get more road debris and salt so blocking the bottom one makes sense.
3. The bottom grill was easier to block due to its shape :)

darcane, have you continued covering the bottom? I would imagine from covering what you did you've only kept the engine bay somewhat clean, maybe expand further backwards and you should see a big improvement I'd think... :-D

avalon: Not sure about the reason for upper block being more beneficial, just that it seems to be the consensus around here. Leaving the tranny cooler unblocked is important and I would leave the top untouched if I were you for that reason.

Lethedethius: I haven't done any further belly pan construction. I have materials to fill in the gaps outside the frame rails between the front and rear wheels and that will likely be my next project. I don't see myself having time to do this for a while.

On the other hand, this morning I made my single biggest mod to date. My driving habits deteriorated significantly today, and yet my mileage jumped from about 18mpg to about 50mpg! What mod you ask? I rode my motorcycle instead.

Mike

Well, by best mod to date is no longer working so well. Last week my motorcycle was stolen. :(

However, I made another improvement on the truck. It had these wheels on it when I bought it:
http://schoolforwinners.com/~darcane...13_Truck01.jpg

Heavy, steel wheels with a fairly deep dish to them. The tires needed to be replaced, so I decided to get some more aero wheels instead (sorry about the poor picture quality):
http://schoolforwinners.com/~darcane...radowheels.jpg

The 4WD trucks had taller tires and these aluminum wheels. Weight is nearly the same in spite of the larger diameter. The face is nearly flat, and the tires fill up more of the wheel well gap. All pluses in my book.

First full tank of gas with them yielded 19.2mpg! So, preliminary results are about 5% better than what I got with the steel wheels.

And I'm at about 22% better than what I got when I bought the truck.

Woot!

Mike

tow hooks
 

I wonder if a later model Chevy or GMC has got pop-in escutchins for the tow hook openings.I think that GM closed these areas off but they may have used a completely different fascia.I'll keep my third eye lookin' out for that.

Tow hook cover
 

You said:

(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.)


You could make a plate to cover the tow hook holes, then use small bungee cords or a stretch rubber to attach it. The pull from the cord would hold it in place, and when you need to acsess the hook, all you would need to do is pull it out and unhook it. :thumbup:

19.25 mpg
 

I ran a quick calculation.If the grille-block cut airflow through the cooling system by 50%,drag would be cut by 6%,which at 70 mph would give a 3.6% mpg increase.A best case scenario,using 18.6 mpg as your starting point would yield 19.269 mpg potential from the single mod.So 18-18.6 doesn't seem to be beyond the realm of reality.Congratulations for lowering US reliance on foreign petroleum!

I like it,
wow, tranny temp went up a bit, the vent at the bottom should have let some air in, wonder why that did not help.
I am in MI and it should help a lot in winter as my ally never goes above 110 in winter.