Project pretty prius grill block
 

I've been wanting an upper grill block for the Prius for quite some time now. Especially now with the PHEV kit and a short commute my engine doesn't even get up to temperature on the way to work and its not even winter yet! After seeing CigaR007's wonderful looking grill block I had to have one for myself. However, There was no way I was going to remove my entire front bumper cover just to make a grill block. Instead, I had recently picked up a great stuff gun for doing some home improvement work. I decided to give it a try for shooting a foamed in place grill block.

I started it last night. I did as CigaR007 did and put down a layer of aluminum foil to act as a backing for the foam. I then just shot the foam in with my gun. The whole process went pretty fast. I was done taping/foiling and shooting the foam within about 45 minutes.

I'll get more pictures later on, but here is what I have so far.

http://ecomodder.com/forum/attachmen...1&d=1319638140

When you shape that foam into shape and smooth the plastic padding with sanding paper. You can check the curvature with that aluminium foil also. Just sweep it ovet the plastic padding and you can see the bigget faults in the vurvature without painting it first ;). Foil mirror the surface pretty nicely.

Good job! Ciga seems to have started something!

Hey, now that is a neat approach. I think I'll try some of this with my Insight. One could quickly make a couple of grill blocks, one for cold weather and one fore moderate weather and just keep the alternate in the trunk.

What is the spray material? I don't recognize it.

For this one I used Great Stuff window and door. It was what I had attached to my gun already, so thats what I used. We'll see how it is to actually work with. It is pretty flexible once cured.

Looking forward to the end result ! :thumbup:

how much was the foam? in my area its usually pricey

Should be about $3-$4 a can. Walmart, Home Depot, Lowes should have it in stock. Same goes fer Ace Hardware/True Value Hardware stores. ;)

Foam in a can is 3-4 dollars around here I think. As I mentioned I used a great stuff gun, it gives much better control and is reusable unlike a normal can of great stuff. I have a picture of it below.


As you can see, you just tuck the aluminum in as best you can around corners and tape it down on the edges.
http://ecomodder.com/forum/attachmen...1&d=1319674698

http://ecomodder.com/forum/attachmen...1&d=1319674698



This is the great stuff gun (pro 14). Its great.
http://ecomodder.com/forum/attachmen...1&d=1319674698



Tonight I sanded down the grill block. It went pretty quick. The only difficulty comes from the fact that the foam is a bit spongy. If you aren't a little careful you can end up ripping it instead of sanding it.
http://ecomodder.com/forum/attachmen...1&d=1319674698


Removed the grill block and trimmed the edges.
http://ecomodder.com/forum/attachmen...1&d=1319674856


As you can see, the surface is far from perfect. I'm going to put some fiberglass over the front face to reinforce it. We'll see what its like after the fiberglass goes on.
http://ecomodder.com/forum/attachmen...1&d=1319674698

Keep in mind that the aluminum foil can scratch up yer grill if you leave it on there. Another option would be to use some plastic food wrap as yer release agent... ;)

Once the foam expands but before it sets up, can you screed it like concrete, cake icing, or spackle compound? If so, you could use a lot less of the stuff, with less sculpting needed.

Also, since foam insulation board comes in urethane with foil backing (R Max?), perhaps a basic plug in the right shape could be inserted into the bumper gap, then sanded or sculpted. R Max is fairly fine consistency, with smaller bubbles than expanded Great Stuff, so sands and sculpts well. Gorilla Glue is essentially the same stuff (just not foamed), so makes good adhesive.

I don't think that would work well. You might be able to do it immediately after spraying it, but it gets tacky very quickly.

From my experience, it is recommended to fill the opening with more foam than necessary and cut/sand the excess. It should leave a fairly smooth surface with no "air" dimples and it is much easier to work with, not to mention that it is less time-consuming.

I'm looking forward to having this done more and more. Today it was a wonderful 29F out when I left for work. I think my max coolant temp hit 159F on the way in and that includes getting stopped for a train coming through which isn't normal. I may have to look into additional engine compartment sealing for winter.

I also still haven't decided how to attach the grill block yet. I'd love to have something that is easy to just pull out should we have a warm day or we need to go on a longer trip as this is our long trip car. Magnets sound ok, so does some form of plastic clip or rubber banding it from the back side or something like that.

You could try eye hooks, flat bar, and pins to secure it to the backside of the grill if you have easy access/space. ;)

Nice. I'm practicing this technique right now to fill the hole left by my passenger mirror delete. Your work looks very clean. I have the bubbly surface too. I'm planning fiberglass too. But I can't work on it now. So I'm happy to live vicariously...

I just got done putting fiberglass over the front. I only used 1-1.5 layers. I'm not sure thats enough, but this thing really doesn't need to be stiff either, it just needs to have that front surface hardened up so I can put some body filler over the top. However, this is only the 2nd time I've ever used fiberglass, so I really don't know what I'm doing! :D

http://ecomodder.com/forum/attachmen...1&d=1320011983

I checked the fiberglass this morning and it seemed to be solid enough to start putting filler over the top. Its still somewhat flexible which is how I hoped it would be.

In this image I can see a fleck of silver that indicates the aluminum foil. In my experience Great Stuff adheres to many many surfaces. I think the foil would be one. So your grill block is foil backed? Did you try to peal the foil off? Did it come off?

Yes, the block is foil backed. It adheres quite well to the foil. I did try to peal it away and it is stuck on there good.

I see you are in a snowy climate like I am. I made a v1.0 lower grill block out of painted coroplast. It looked great till I drove in the winter. By spring it had holes punched right through and showing white coroplast. I ended up gluing some thin black foam rubber over it to protect from impacts. Ya might consider putting another layer of glass on while it is still easy to do...

I've never really had a problem with puncturing grill blocks (even lower grill blocks) and I've had them made of weaker material than coroplast. That plus the subsequent layers of body filler (bondo) will strengthen it more.

And body filler was the treatment I put on last night. First, I trimmed off the excess fiberglass and sanded down the edge back to where I wanted it to be. I used a dremel tool cutoff wheel and flap sander to speed things up.

http://ecomodder.com/forum/attachmen...1&d=1320150025



Then, the first coat of bondo went on. My wife even took a shot at applying it (since we just got an old truck to restore and she wants to help) and did a pretty good job. I did the other half myself.

http://ecomodder.com/forum/attachmen...1&d=1320150025



Then of course comes the fun part, sanding!!! woohoo... not really. I used a random orbit sander and sanding block (actually a drywall sanding block) to knock it down. The first coat turned out pretty good. That fiberglass mat was VERY uneven and the bodo filled in the lows pretty well. Hopefully one more coat should do it.

http://ecomodder.com/forum/attachmen...1&d=1320150025



At this point, I'm going to say the foam backing is really beat up. Trying to hold thing thing without smashing the foam has been a pretty big pain in the butt. Its hard to apply pressure when you can't hold the back of the thing you're wanting to push on. I'm not sure how this'll effect the end product, but just thought I'd mention it.

Looking good.

Just a reminder to people following this project: make sure you clean or rough up the fiberglass before applying anything over top. Some 2-part resin/hareners produce a slightly waxy film (blush) on the surface when they cure, which you need to remove for best adhesion of more layers or other material.

Yep, that was done. Even with the fiberglass being so uneven I just roughed it all up a bit.

Better check a small section of the foam for compatibility with the fiberglass resin before you get too far. Some of those materials are not compatible.

Thanks for the warning Jim. It seems to be doing just fine.

However, the foam really is getting mashed up just from handling it. I'm thinking I might just remove it once I'm close to done.

I did some more work on the grill block last night. It got another coat of bondo and its looking pretty good. After knocking off all the edges and obvious high spots with a random orbit sander I applied a guide coat. All a guide coat really is is spraying the bondo lightly with some spray paint. Then, you take a board sander (long flat sanding block) or in my case my drywall sanding block and go over the grill block. You'll sand off all the high spots leaving the spray paint on the low spots. You need to keep sanding until all of the spray paint is gone, or you decide to put another coat of bondo over it.

http://ecomodder.com/forum/attachmen...1&d=1320236721

http://ecomodder.com/forum/attachmen...1&d=1320236721



Here is what it looks like after we've done a lot more sanding. The left side still needs more sanding, but the right side is looking very good. They both need some filler around the edges though.

http://ecomodder.com/forum/attachmen...1&d=1320237141

http://ecomodder.com/forum/attachmen...1&d=1320237141



The darker patches you see here are fiberglass, not the guide coat.

http://ecomodder.com/forum/attachmen...1&d=1320237141

Prediction: this is going to turn out nicely. :D

Thanks Darin. I think its coming along pretty well. Its only my 2nd time doing anything with fiberglass and bondo (and I never finished the first project). However, I've been spending gobs of time on youtube the past week or so researching how bodywork is done for working on the truck restoration. I didn't even know about guide coats until last week. :)

Hey Daox,

This is going great, man, really awesome to watch you going at it. This was the exact idea I had a while back when I was thinking about doing this. Of course, then I figured out that hypermiling when most of the driving I do is in a fair bit of traffic is pointless. I think I MIGHT still do a mod like this, though, and maybe a few others.

Might I suggest perhaps covering the entire thing in fiberglass? That would really stiffen up the backside of it, keeping it rigid for work, but very lightweight.

The fiberglass, by the way, is definitely the missing component insofar as I'm concerned... I had experience trying to do molding with this stuff - no way for anything large and flexible!

Looking forward to seeing the final result!
Tony Richfield, WI 2010 Prius II

I thought about fiberglassing the whole thing, and that might have worked had I done it right off the bat. However, its now mashed and disformed from holding it while sanding. So, that is no longer an option for me. The only thing you'd have to be careful with if you did do it that way would be fitment issues. Since the foam expands between the grill's slats, you would need to sand that foam down before putting fiberglass over the top otherwise it might not fit back on well. I'd think it would also probably scratch the paint on the grill slats if you are worried about that.

Another thing a person could do is to lay the glass mat right on the aluminum foil. Let it set up; then fill it with foam to the thickness you need; sand down the foam then glass over it.

Excellent idea, Quasimoto!

Yes, that would have worked much better than what I did. New ideas for next time! :)

Or for me! :P

I love my Corolla (now), but I really would like to do something for a little bit better mileage...

In order to avoid the foam to be crushed while sanding, I kept it on the upper grille for support (which is removable on my car), especially when I applied the epoxy resin coatings. That way, the foam maintains its shape and it is not damaged in any way. I did not use fibreglass though. Seems to be quite solid without it, even after a few months of usage. We will see how it handles the winter.

I say don't worry about the back. Carve it out, glass in some rare earth magnets, and put some brackets in the nose with matching magnets. Easy removal, but will stay put. Well, easy removal if you don't go too large on the magnets ;-)

You can put foam tape on the back to protect the grille if needed.

Yeah, I was thinking some foam tape would work nice for protecting the car's paint once it was done.

Magnets would be a cool way to attach it too.

finally, some areo mods with a clean look to them..

And it didn't cost a while lot to do.. :)

i want to mod my Corolla, but retain some sort of clean look..
I'll be doing something like this as soon as I find a doner grill..

That is going to look a lot nicer than our typical grille block method.

Here is the method most of use Prius owners run:

http://www.fatalfoo.com/pics/Cars/Pr...ation%20sm.jpg