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-   -   Lil' Red's Aero Mods (

sohl 07-20-2008 12:16 AM

Lil' Red's Aero Mods
I'm starting this thread to track my aero mod(s?) to Lil' Red, my 2003 Mazda Protege. First up, the "Stealth Grille Block" ...

sohl 07-20-2008 12:38 AM

The Stealth Grille Block
I wanted to try an air block on my upper grill. Here is my original grille area:

I wanted it to look clean not be too noticeable, but not take a lot of time to install and not be permanent in case I ran into cooling trouble (not likely in Michigan) or some other unexpected problem. I thought a while about various ways to do it, then got a really interesting idea today. Here's the grille block installed:

See it? No, its not on the back side of the grille... ;) Here is a hint:

I wrapped the front of the grille in heat-shrinkable window film... the stuff you can use to add insulation to your house windows in winter.:D

To install it, I first studied up on how to remove a Protege grill and the glossy rim strip that runs along the top of the grille. Then I put the window film double-sided tape all around the outside edges of the grill (the parts that butt up against the bumper and trim. Then to improve air-tightness, I placed some foam tape around the bottom and sides:

Here is the front with the trim strip along the top. Notice the camera flash off the surface of the film?:)

I just installed this, so I need to drive it a few days and see if it will cause any obvious problems. It would be nice to do an ABA coast-down test, but it's hard enough to find time to squeeze in even quick projects like this one.

This window film stuff is fairly strong, though I'm sure a rock could punch a hole in it. And I don't know if the tape holding this on will be waterproof. So we'll how long it holds up. It only took about 45 to 60 minutes to install, so it's no big deal if I want to replace it after a while. Even if the window film does not hold up, if the grille block works well in terms of FE, maybe I could fashion a more permanent one. I do like how smooth and practically invisible this is for now. :thumbup:

Updates later on driving experiences and if it stays on over a few tanks of fuel, we'll see it's effects on my mpg's.

Will 07-20-2008 12:43 AM

I would wonder if a bug might punch through it at highway speeds... I really like that you are starting this thread on a sedan. I may soon be looking at tinkering with my wife's Century. I look forward to "borrowing" your ideas.

justpassntime 07-20-2008 01:03 AM

Looks good, it will be interesting to see how long it lasts. It lasts awhile on a house, but it's not going 60 down the highway.

Hmmm....If this works, I wonder if you could shrink wrap a whole car with the stuff they use for boat storage? Just cut holes in it for windows and you have an instant aero gap filled car. Sure would be smooth.

sohl 07-20-2008 11:09 PM

I'll be happy if I get a month or two from it. That way I'll go through a few tanks of gas and might see a change, although I'd expect the drag reduction will be slight, and I don't spend a lot of my miles at highway speed. But by then, after driving through the hot part of the summer, I'll know if an upper grille block is feasible in my Protege.

This upper grille is fairly small, and at least the film over the left and right edges away from the Mazda emblem are supported by the original grille structure, so I'd hope bugs and grit will not hurt too bad. However, the few inches around the emblem is kind of "tented" up, so a small stone or hard bug there might poke through. Or curious kids. We'll see!

Xringer 07-21-2008 01:05 AM

Neat idea and it looks great!
To make it tougher, I'll bet you could just add a couple of layers on top of each other..

MazdaMatt 07-21-2008 11:06 AM

I was thinking about something like that for my entire prot5 front bumper. I never thought about window film. Wise choice :)

sohl 07-21-2008 01:48 PM

The film has held up to around 25 miles up through now, including a few miles at freeway speed. I notice a few very small wrinkles today, so it might be getting a bit loose at a spot or two. I'll try a bit more hot air ;) to smooth it out.

Xringer: I actually had two layers when I first put it on, but the layers don't adhere to each other evenly, so you get a weird blotchy look. I'm thinking that it could be done with an even tougher film, like the mylar (?) used for model airplane construction.

MazdaMatt: If you want to try it, look up the grille removal discussion in some of the forums for Mazda-dedicated sites. I could dig up a URL if you can't find anything. The glossy/chrome strip along the top edge of the upper grille can be removed to help you wrap the film, but I think it's much better to do it after taking the upper grille off the car so you don't damage either part.

sohl 07-31-2008 02:06 AM

Black Upper Grille Block
Well, the window film grille block was still intact and doing its job, but it was starting to loosen a second time, and the latest hot air treatment only seemed to last about one day, so I decided to replace the film with black plastic.

The material was liberated from an expanding portfolio, and I think is some kind of polyethylene, maybe similar to what Craig Vetter is using on his Aero Helix scooter.

I made a paper template and used scissors mostly to cut the plastic.

I made the plastic in two sections. Here is the first side fastened.

I used zip ties to fasten the plastic, after drilling small holes (inside view):

Here is both sides fastened. The black stock trim piece is used to hold the top portion of the grill block to the front of the grille. So I only used three zip ties on each side along the bottom to secure it. If it starts to come loose, I can add more zip ties later.

Here is the re-blocked grill installed on my Lil' Red Protege:

Here you can see the open area inside and below the Mazda emblem:
The open area (about six inches of open area, I believe) will allow a bit more cooling air into the radiator, although I did not notice any temperature elevation from the window film block.

I may block the sides of the lower grille in the future, so I don't feel the need to fully block this upper grille right now.

Total time: about 2 hours, plus 30 minutes to post here :D.

digitaldissent 07-31-2008 03:07 AM

looks very nice :)

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