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Old 11-20-2012, 05:29 PM   #1 (permalink)
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Ecomodder Evangelism: Help (explaining air dam with grille block on Instructables)

In an effort to spread the word about fuel efficiency I posted my air dam project over at instructables.com. It was well received by the editorial staff and featured in the Workshop section and on the front page. However, not every one was convinced. There were several skeptics that chimed-in in the comments section. I tried to explain things the best I knew (all credit to you folks here at ecomodder.com) but I could use some help from you all in filling in the blanks (or correcting my logic.)

Please stop by at Gas Saving Front Bumper Air Dam and share your opinions and knowledge. Much thanks!

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Old 11-21-2012, 12:16 AM   #2 (permalink)
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Oy. Looked to me like about one, maybe two posts out of the whole mess were correct. :/ That much education is a bigger project than I want to take on.
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Old 11-21-2012, 04:07 AM   #3 (permalink)
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Uh....Sorry to criticize, but I think plugging your entire lower grill was not the best way to go. You should have closed off the top grill entirely, and left a hole in the middle of the bottom air intake. Then if your up to it, extend the air dam lower a few inches if possible to limit the amount of air going under the car.

By leaving the upper grill open, it prevents air from going the easy way over the top of your car and puts it through the radiator/engine bay. If you leave the lower grill open a bit, the air there was doomed to go under the car, or all the way around the sides past wheels & such, anyway. So air going through the engine bay via the lower grill is more efficient.

When you do block a lower grill, you do want to block the sides first and work your way to the middle.
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Old 11-22-2012, 02:24 AM   #4 (permalink)
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Well, sorry to say I screwed that up. Here I thought I was saving the planet and was going about it all backwards. The lower bumper was thrashed and needed to be replaced so taking my inspiration from AndrewJ I smoothed out the front to make what I took to be the bottom part of an air dam.

Thanks for the info.
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Old 11-22-2012, 08:54 AM   #5 (permalink)
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Not that is doesn't have any effect. As I understand it there are several variables in play here. Having reduced the amount of air going through the radiator and engine compartment, a good thing and in theory reduces drag. But the question is now where is that air going around the sides under the car or over it and what effect is it having. While it is the common practice to block the upper grill first that really depend on the car. There has been some discussion that some upper grills on certain cars stair step the air over. Also some discussion that in hot areas in stop and go traffic that less total opening the higher up the opening, the theory being the air temp was lower further from the road surface.

So, it is not straight forward. In general look at what other have done with your model, specifically any that have done testing. Testing was needed to determine what benefit the change has. But if the front damage was as bad as you described it, you probably didn't hurt it. Hate seeing front end parts flapping in the breeze. Then there is always revision 1, 2, 3.
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Old 11-23-2012, 07:48 AM   #6 (permalink)
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Quote:
Originally Posted by bertb View Post
Well, sorry to say I screwed that up.
What effect did it have ?
Let that decide wether you screwed up or not

But as ChazInMT says, we usually start with blocking the upper grille first.
Blocking the entire lower grille can also be a bit too much, depending on the weather and season.
And it can block air flow to transmission / AC / or inter cooler - if you have any of these, see that it can still get some cooling air.

Quote:
Here I thought I was saving the planet and was going about it all backwards.
It's better to try and fail, than not to have tried at all

Quote:
I smoothed out the front to make what I took to be the bottom part of an air dam.
It IS an air dam.

Just make sure you can get away (cooling wise) with this kind of blockage - and the top grille.

FYI : 1990s Honda's had little or no top grille .

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