Aero Mod Questions

[ChopStix]

Hello,
So in reading the list of mods that can help increase MPG. I have some questions related to aero mods. I'll ask them one at a time so as to not complicate getting answers.

I saw this picture shown in the list of efficiency mods.
http://ecomodder.com/imgs/mods-list/45.jpg
Its clearly increasing the frontal area of the truck. Because its bigger than the stock front end. Granted it does cut more air going under the truck. But its still bigger. So I have to make the assumption that it made a difference or else it would not have been chosen for this list.

Can anyone explain why this air dam above is better than me running one of these air dams specifically made for my truck?
Chevy Astro Van Front Bumper

[dfeldt91]

The mod in photo would be cheaper(thus saving money since you would be spending less to get the fuel savings).

Next question?

[oil pan 4]

Its a matter of $400 versus essentially free and works better.
Those are the main differences.

[spacemanspif]

Cost vs. looks is all it comes down to. The body kit front end would do the same thing but the splitter that's kinda built in would increase downforce a little. Usually body kits would not be a gain due to the front bumpers typically having giant holes for cooling and better looks than a solid front bumper. Some Astros had pretty big factory dams I thought, if you don't have anything search around and look to see what factory options were, fit and finish will typically be better with factory pieces and a junk yard dam would cost about the same as a DIY dam.

[NeilBlanchard]

Greater frontal area, yes - but with a lower Cd, it is probably lower drag than stock.

[Piwoslaw]

A massive airdam is better than a dirty underside. If your vehicle has a smooth bellypan, then adding an airdam may worsen overall aero.

But a smooth belly is much harder to achieve if your car did not have one already, and usually more expensive, which is not always justified by the gains. An airdam will give smaller gains (in most cases), but much is cheaper and easier.

[ChopStix]

Awesome! Thanks, those replies answered my next 2 questions.

Its worth noting that we live in a world where everyone seems to be about making more HP over getting more MPG. Cold air inductions over hot, bigger cams, compression, etc. I have to re-learn about working on cars. Because most car magazines oppose everything that this forum is all about.

So my next question would be, what effect does side and rear ground effects do for the goal of increasing MPG? Something like these:
http://www.andysautosport.com/images...est/890213.jpg

[oil pan 4]

Ground effects = side skirts that don't go down as far as they could.

You don't have to run a warm air intake all the time.
http://ecomodder.com/forum/showthrea...ake-33039.html

And check out the wiki.
Car MPG Efficiency Modifications Main - EcoModder

[ChopStix]

Thanks for the replies, everyone. You are helping me learn, which is a great thing!

Originally Posted by oil pan 4

Ground effects = side skirts that don't go down as far as they could.
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So are you saying that generally speaking, side skirts that go lower are better for MPG than these skirts that I linked a picture to?

[Xist]

I am honestly not sure how much air dams actually increase the frontal area. We say not to have them hang lower than the lowest part of your suspension. Basjoos has double side skirts. Have you read about the Aerocivic? If it helps, he has probably done it.

Basjoos's side skirts are coroplast: http://ecomodder.com/forum/showthrea...1-0-a-290.html

These members used rain gutters: http://ecomodder.com/forum/showthrea...rts-10749.html