DIY - Front Grill Block - 1991 Honda CRX

[SVOboy]

The front grill block is on of the quickest, easiest, and cheapest ways to cut down on aerodynamic drag in your vehicle. While it doesn't amount to much, it does make a difference, especially considering that a large amount of aerodynamic drag is caused by this opening. It's best to leave it only partially blocked so that the radiator recieves some airflow, however, a large block is okay because radiators are typically larger than they need to be, and fuel economy drivers tend not to abuse their engines too heavily.

Many new cars, including certain Mercedes and Hondas use electronically controlled radiator shields that open/close depends on engine cooling requirements. Take a look at this Civic for an idea what this looks like:



Purpose: To prevent air from entering the grill to reduce drag as it moves through the radiator and engine bay.

Time: 1-3 hours depending on complexity of project

Tools:
- Hobby Knife
- Hot Glue Gun


Supplies:
- Coroplast
- Spray Paint
- Foam (for modeling)

I chose to repaint the trim on my bumper as well as do the grill block at the same time, so first I removed the bumper. If you leave it on you can get it done much more quickly, but that's up to you. Just follow my mounting instructions with the bumper on the car.
Click here to see how to remove your bumper (as shown in the wire tuck page).
This is my bumper removed, you can see the grill opening as well as the two pockets on the side. The side pockets are not supposed to cause much drag but I covered them anyway just to smooth thing out as much as possible:

Here's another shot to get an idea of the bumper's geography:

I used this style of insulation foam to make templates because it is easy to work with:

One of the templates sitting in a side pocket:

I then transfered the template to the coroplast, cut some support to place down the side of the pocket to mount the coroplast to, and cut off part of the coroplast towards the center of the bumper so it would mount flush to the bumper where it tapers together:

The center pieces are just glued to the ribbing on the grill and then glued around the edges from behind:

I taped up all the painted portions of the bumper so I could respray the trim and the coroplast black:

Two shots of the finished product remounted:

I think it turned out pretty darn good,

[deadman1474]

good idea I could not do that on my truck though it would overheat so fast. After I get the front nice and muddy it starts to rise the heat. Not that bad but still noticable. And same when I have the plow on it. How dose a mod like this effect your car tempature.

[SVOboy]

It hasn't really affected it at all. My radiator was very much over sized to begin with. *shrug*

[Daox]

Looks good to me.

I was wondering though, what did you use to cut the coroplast? I just found a supplier in my area and will be picking some up for some mods to the Matrix soon.

[SVOboy]

I think I use an exacto knife...which is dangerous. Dunno if I listed it in the DIY but I dropped the knife into my knee about half way through and cut my quad tendon pretty badly, was hobbled for a long time, so be careful,

[s2man]

SVOboy, I can see the pics of the new Honda, hosted by autoblog, but not your pics. Your site says the edrive-images-crxmpg-com directory is not found (insert crying smilie here).

The winter weather did a number on my cardboard grill block. So I finally got my permanent Coroplast block installed a couple of weeks ago, when we had some nice 50*F weather. Here's the before
http://www.themillers.us/images/cava...ckTempOld1.jpg
and after
http://www.themillers.us/images/cava...BlockFinal.jpg
shots. I was able to tape a large piece of paper on my bumper. and get the outline of the grill opening by rubbing with a crayon. The perimeter of the block was sealed with black silicone. It's attached using six black wire ties and four black license-plate bolts.

Daox, I used a utility knife to cut the Coroplast, and only ended up with one cut on my finger. But not from the knife, from pointy end of a compass I was using to scribe an offset around the edge of the Coroplast! Much better than a cut tendon.

deadman, my cardboard block had no affect on the engine temps when I installed it last summer. There is a huge opening underneath, between the bumper and the air dam. I added the molding at the front of the hood this winter, and was still running cold. I had to block my radiator with cardboard to get the engine back up to temp.

And no, I'm not going to block the bullet hole on the passenger side. That's a memento from the 'hood.

[cfg83]

s2man -

Originally Posted by s2man

SVOboy, I can see the pics of the new Honda, hosted by autoblog, but not your pics. Your site says the edrive-images-crxmpg-com directory is not found (insert crying smilie here).

The winter weather did a number on my cardboard grill block. So I finally got my permanent Coroplast block installed a couple of weeks ago, when we had some nice 50*F weather. Here's the before
http://www.themillers.us/images/cava...ckTempOld1.jpg
and after
http://www.themillers.us/images/cava...BlockFinal.jpg
shots. I was able to tape a large piece of paper on my bumper. and get the outline of the grill opening by rubbing with a crayon. The perimeter of the block was sealed with black silicone. It's attached using six black wire ties and four black license-plate bolts.

Daox, I used a utility knife to cut the Coroplast, and only ended up with one cut on my finger. But not from the knife, from pointy end of a compass I was using to scribe an offset around the edge of the Coroplast! Much better than a cut tendon.

deadman, my cardboard block had no affect on the engine temps when I installed it last summer. There is a huge opening underneath, between the bumper and the air dam. I added the molding at the front of the hood this winter, and was still running cold. I had to block my radiator with cardboard to get the engine back up to temp.

And no, I'm not going to block the bullet hole on the passenger side. That's a memento from the 'hood.

Grill block looks good!

How about clear packing tape, or a black plastic snap-in cover (they're in the specialty fastener section in most hardware stores)?

Hole Plugs: 3/16", 1/4", 5/16", 3/8", 1/2 inch, 5mm, 8mm, 10mm, 12mm

CarloSW2

[TXhonda]

good job!! Looks great. I'd have thought it came from the factory that way if you hadn't told me...
But any ideas on how one can do that in a more southern climate and not overheat?? What is the normal daily temp in NH during July/August !?!??
It was 100 here the other day and with nothing blocking my grill, I could notice that my '98 civic was a bit hot :^)

[MazdaMatt]

The comment re: mud causing overheating made me realize... maybe people who go mudding should use a grill block and duct air to their rads. Then you'd get the aero benefit AND you'll never get your rad blocked up with mud! I'm going to mention this to my cousin for his lifted Jimmy.

[SVOboy]

Originally Posted by TXhonda

good job!! Looks great. I'd have thought it came from the factory that way if you hadn't told me...
But any ideas on how one can do that in a more southern climate and not overheat?? What is the normal daily temp in NH during July/August !?!??
It was 100 here the other day and with nothing blocking my grill, I could notice that my '98 civic was a bit hot :^)

Welcome to ecomodder! A smaller block is definitely a good call for warmer climates. I would experiment and see what works.