My T-100 grill blocks over the past few years...
 

Here's quick photo history of my grill blocks... :D

Grill block using Coroplast shutters (one closed)
http://i164.photobucket.com/albums/u...Picture013.jpg

Grill block using Coroplast shutters (both closed)
http://i164.photobucket.com/albums/u...Picture007.jpg

Grill block (open) using Coroplast shutters (painted black) and tape
http://i164.photobucket.com/albums/u...Picture021.jpg

Abandoned the Coroplast shutters as the tape failed over time and I didn't have a good way of securing the shutters at the pivot point. :(

With my new T-100, I started out using pipe foam insulation. Just ziptied in place. Found out the foam shrinks over time when exposed to the sun and engine heat. Reinforced the center with PVC Schedule 40 pipe. Foam insulation breaks down over time due to the environment... :(

Grill block using foam pipe insulation (33%)
http://i164.photobucket.com/albums/u...0/IMG_7138.jpg

Grill block using foam pipe insulation (67%)
http://i164.photobucket.com/albums/u...0/IMG_7388.jpg

First iteration of the Coroplast grill block (67%) taped in place. Gorilla tape eventually started pulling off over time.
http://i677.photobucket.com/albums/v...s/IMG_8053.jpg

First iteration of the aluminum grill block (67%) taped in place. Duct tape eventually started pulling off over time.
http://i677.photobucket.com/albums/v...s/IMG_8187.jpg

Last iteration of the aluminum grill block (67%) screwed in place. I used 1" PVC PE200 pipe fer the backing support.
http://i677.photobucket.com/albums/v...s/IMG_9084.jpg
http://i677.photobucket.com/albums/v...s/IMG_9100.jpg

Since pulling the aluminum grill block since it was gitting pretty hot here, I only had the top 1" PVC tube doing grill block duties. So I went and custom cut a new tube and painted it black. Ziptied it to the grill. Seems to be a winner... :D

I didn't use Schedule 40 PVC...I used the PE200 since it's thin walled and easier to shape/work with. I ground the ends to shape by rubbing it against the cement road... ;)

33% grill block...wide view.
http://i677.photobucket.com/albums/v...s/IMG_0999.jpg

Close up view...
http://i677.photobucket.com/albums/v...s/IMG_1002.jpg

What happened to the aluminum one? seems like the best solution.

It's sitting under the aero cap fer now. It will probably git reused into something else down the road. It was too involved just to revert it to a 33% grill block when it got too hot. :(

I'll use 2 more shaped pieces of PVC pipe painted black to bring it to a 67% grill block once the temps drop back down. When the road chips git too bad on the pipe, I can touch up the looks with more flat black paint. :D

I might eventually go with a locking mechanism on the backside of the tubes to lock them down vs the zipties I have on there now. ;)

It might be possible to resurrect the shutters method using a different material like aluminum instead of the Coroplast. The Coroplast shutters flexed too much when they were in the open position. I first worked with the shutters about 4 years ago and I believe my experience in building things has grown since then. ;)

I'm thinking about adapting a spring loaded method that keeps the shutters open when the truck slows down enough and doesn't prevent the shutters from closing at speed. The pivot of the shutters behind the grill will be key to how well it responds to the air flow. :D

My original concept thread...over at GasSavers.org. :D
Adjustable grill block...fer a T-100! - GasSavers.org - Helping You Save at the Pump Hypermiling and Fuel Efficiency Forum

Went with a 50% grill block. Daytime drive to Dallas was uneventful...until I got into rush hour traffic. Ambient temps were around 108 degrees! Stop and go traffic pushed the coolant temp to 230 degrees! The stock coolant temp gauge needle was just past halfway. Didn't blow up or lose any coolant...whew!

Pulled the grill blocks after I got to Irving and didn't have any problems with temps from that point on. Drove home later that night without any grill blocks. Cruise set to 60mph and the indicated MPG was around 25mpg.

Now I'm thinking about going back to my original concept design with the shutters. Time to do some more work... :D
_________________

temps
 

In the 1970s I took an engine rebuilding course at Lancaster Community College and some of the students brought up the topic of coolant temps to our instructor (Factory-trained Volkswagen Master Mechanic) and he didn't think we needed to sweat it too much.
At the time,I believe it was Buick which was running over 20-lb cooling systems with 'normal' operating temps of 255-degree F.
He said that as long as the system was clean,the coolant wasn't over-age,system pressure was holding,and heat-exchangers clean,that there shouldn't be any alarm with temperatures well in excess of boiling point.
Engine oil can go over 350-degrees F without trouble.This would be in the normal operating range for a Beetle or Ghia.
Maybe 230-F isn't a problem.Manual might say.

I know it's an old thread but I got to say "Thank you BamZipPow!". I have been looking for ideas for a better grill block for my truck ('93 Toyota pickup), currently I have a piece of cardboard with a small center portion cut out in front of my radiator. I know it's not the best, that's why I'm looking for a better alternative (really liking the pipe insulation). I'm thinking a 70-80% block would work for me, I have a short drive to school in the morning and the thermostat only starts to move by the time I get there.

Thanks for all the pictures! They give me alot of good ideas.

Inspiration is one of the key points to innovation. Glad to be of some help. ;)

Keep in mind that you'll probably need to insert some PVC pipe inside the foam or it will shrink up on you. Also, the foam will break down due to UV exposure so yer setup will be limited to about 6 months or so depending on how much UV hits the foam. I initially used some velcro zip ties I got from Harbor Freight to secure my first grill block to the grill. Depending on yer grill, you'll have to see what will work. Keep in mind that if you need access to remove the grill block in case of overheating, you'll need to consider that if the radiator is hot and bubbly. ;)

BamZipPow,

I notice that you have also included some serious side skirts below the body of the truck.

What has been the mileage increase from this modification?

I have considered doing the same to my F150 but was not sure if it would be worth the effort. Would you do the side skirts again?

Goldenstate