What % in MPGs would this grill block realize?
 

???

Grille "block" LOL

That depends if you're driving it in 4ft. of snow... ;)

Two points:
(1) The top should be sloped down slightly.
(2) What is that sticking out of the sides? A bumper? Cover that, please, my eyes, oh!!

No, really, it looks quite nice, though I'm sure why it reminds me of winter? There will definately be an FE gain, I'm guesstimating 3-5%. The front edge could be rounder, though.

some new mercedeses have awedge shaped front, although not as dramatic as this i think it's because it allows for a relative bold front end but with better aero than something flat.

what i'd be a little worried about though is the corner radius wich isn't there anymore. there wasn't much of a rounded corner there to begin with but combined with the stagnant air bubble at the front the overall ticture could have been something quite round to the air.... it looks as if the air comming of the sides of this mod has little change to attach to the side of the vehicle... what you often see in windtunnels is people tweaking small details like smoothing corners up front and shaprening them at the back. not easy to do in wood, and without the wind though

Mandilon -

Here's one that scored an MPG award :

Modified Honda CRX HF Scores 118 MPG in Fuel Economy Run | Hypermiling, Fuel Economy, and EcoModding News - EcoModder.com
http://ecomodder.com/blog/wp-content...8/dsc_0418.jpg

CarloSW2

I'm still having some difficulty with the notion that wedge helped.

Not sure about the Cd, but if you just taper it a bit towards the bottom, you'd have a nice start on an amphibious van!:D (Note that I smile as I say that...all in good fun.)

Since you are not trying to break the sound barrier, you would get similar results if you just plugged all the holes in your grille and made the front end as smooth as possible.

A blunt front end can be just as streamlined as a sharp pointed one at low velocities. The ideal shape at highway velocities is a teardrop - not a pointed box.
http://ecomodder.com/forum/showthrea...ends-2914.html

You might take a look at a Kamm back modification such as this one :

http://ecomodder.com/forum/showthrea...evia-9437.html


I see that you shielded the A arms with this design - you'll definately see some gains there.
You could also use flexible rubber sheeting as an airdam, and you wouldn't have to worry about pot holes and such.

Austin eh ? I'll keep a look out for your van !

3% mpg
 

the grille block portion of your mod would net you a 3% mpg improvement tops.The mods you've pictured would affect other things as well.Not to sound like a know it all but,air doesn't like "wedges",they create very unstable flow acceleration and you could still experience separation where the mods integrate to the vehicle.Increasing the leading edge radii instead,would net you greater improvement.If you were looking at the nose from atop a ladder,the ideal nose would appear as a semi-circle.

It's all gonna get scraped off pretty soon anyway.