Suggestions on grill-blocking my 03 Lancer: post-election coroplast!

[FLAteam]

Well, the elections are all over and I was able to pick up some political signs. I want to make a grill block for my 2003 Mitsubishi Lancer, but there's a lot of choices in terms of location. Here's what the front of my car looks like:



Here's a different angle:



The two side "vents" under the headlights are actually blocked off already by plastic; its just for show, but I assume they're not as good as a flat surface for aerodynamic purposes.

The center bottom is covered in black plastic mesh and leads to the radiator. The center top also leads to the radiator, but also the air intake is located at the very top of the grill.

So, which parts should I block off first? I was always under the assumption the top nose part should be blocked first, but based on what you can see here, what do you all think?

Thanks.

[theholycow]

How do you acquire the post-election coroplast? I don't know how to get it, besides asking permission and collecting, one at a time...which would be tedious and time consuming. I was thinking of maybe posting an ad in town hall if there's a bulletin board there.

I think the upper grille isn't as much concern as the lower. The lower is a bigger parachute-like shape. Also, the lower almost certainly supplies much more airflow into the radiator and engine bay.

Your car is configured just like mine.

Here's my grille blocking threads:
http://www.gassavers.org/showthread.php?t=8597
http://www.gassavers.org/showthread.php?t=7839

Your timing is perfect. I came in and checked for new posts in between coats of Plasti Dip on my grille block that I intend to complete Real Soon Now. Then I wrote most of this post, and spent 20 minutes struggling with Picasa which doesn't want to run. Finally my stuff got uploaded...here's a preview of what my car will look like:

[Jay2TheRescue]

Grille blocking... everyone has their own theory. HC had a good suggestion, but here's my thoughts - free of charge and its worth exactly what you pay for it...

My logic dictates that if only one was to be blocked I would start with the top grille, and this is why. The top grille is angled and blocking that will let air there glide up and over the top of the car. Since the lower grille is relatively flat it will push air in all directions. Some will go up and be rammed into the upper grille, some will be pushed to the sides, and some will be forced under the car to the airdam.

Following this logic if one were to only block the top grille it would not be by default forcing more air into the lower opening as its angled and set back. Deflected air isn't going to forward a few inches and then get forced in the lower. Its either going to be pushed to the sides or top of the car. Plus, if you do a 100% block on the top you are free to do a partial on the lower and get your airflow tweaked. A partial on the lower will be more stealthy as the car will have a more uniform appearance.

So there you have it. I say top.

-Jay

[FLAteam]

Thanks for the input. I got the post-election coroplast by visiting my local democratic party headquarters and asking them if they had any leftovers. Plus, they said I can take any on public ground. I couldn't find the republican headquarters...

I definitely see how blocking the top would direct air to places that would allow for better flow. The lower grill seems like a much harder job (I saw some of the materials and methods to make it flush with the bumper, and it seems rough). However, theholycow, you've given me great ideas on what to do with my lower grill block (with the styrofoam and stuff), so I think I'll start with a full top block and gradually make a partial to full lower block.

That being said, what do I do about those pesky side indentations? they seem to just act like parachutes, but maybe they're less of a concern than the totally open parts.

[theholycow]

The side indentations on your car look like they might be easy to do.

1. Cut styrofoam to fit, gluing on additional bits as necessary.
2. Use any kind of plastic sheet as the surface.
3. Caulk will attach it securely, due to the shape of the hole and the size of the piece you'll need to make. Caulk around the edges and maybe a couple dabs on the back.

Definitely way easier than mine.

[Jay2TheRescue]

I would not be as worried about the fake vents in the bumper. As you drive you will have a "pool" of air in the small cavity. Since this is full any other air would be pushed to the side. Kind of like leaving a glass in the sink and turning on the water. Once the glass is full the excess water just overflows. No further pressure is exerted on the glass. Your main concern is to keep air from going through the car. Later on when you really start getting technical you may want to experiment with filling in the vents, but I'd say the gains would be very small. Your efforts are better spent elsewhere right now.

-Jay

[winkosmosis]

Why is air going through the car bad? That air wouldn't present as much resistance on the front. Are you guys worried about disrupting airflow under the car?

[Jay2TheRescue]

Because the engine bay is acting like an open parachute as the air goes through the grille... Blocking the grille allows the air to go around the car instead of through it.

-Jay

[winkosmosis]

The air comes out of the bottom though. The way I'm picturing it, air going into the grill and out the bottom of the car can help aerodynamics by pushing the airflow around the rough components. Also, if the bottom is reasonably streamlined, the slipstream could pull air out of the engine bay, causing suction at the grill.

[Jay2TheRescue]

Its not a straight path though... It has to squeeze through the radiator and a/c coils, then it hits the fan, then it hits the engine and forces its way through and then its under the car (which on most vehicles isn't very aero-friendly). Grille blocking keeps the air on the body of the vehicle where the body design is made to deal with it, and a side benefit is that the vehicle warms up faster and usually has higher intake air temps which both help economy.

-Jay