Aeromodded Civic VX 72mpg (image heavy)

[The donkey CRX]

John, When I got this VX it did not have the "rubber" side trim. I think I read somewhere that the VX model did not come with them. (weight savings?)

[basjoos]

Originally Posted by johnlvs2run

Basjoos, what is your opinion on this? I'm planning to have the same type of nose as Aerohead & The donkey CRX. I'm thinking to cut the plastic at 7 or 8 inches from the ground, but wondering if 6 inches would be better.

I didn't install an air dam on my car, so I can't answer your question directly. Since I installed smooth underpanelling and greatly lowered the stagnation point to divert up and over most of the air that might have gone under the car, I didn't feel I needed an air dam considering its negative benefits; increased frontal area and their unintended function as road kill possum/raccoon scoops, which often damages them when you pass over one. If you look at the ultra low Cd solar racing cars, none of them have air dams. Rather they have smooth bellies, skinny wheels and lots of ground clearance. Sort of like an aircraft fuselage flying close to the ground, and I decided to go that route with my car as much as I could. An air dam is quick and easy way to divert air away from the rough and draggy underside found on most cars. It also increases down force by creating a low pressure pocket under the car. In the typical opened bottomed engine compartment, this low pressure pocket also increases air flow through the radiator, which is a benefit in the wide open throttle world of racing, but not necessarily so when driving for mileage since extra cooling equals extra drag.

To get back to your question about airdam ground clearance, I made most of my ground effects items (wheel spats, side skirts, etc.) of coroplast, so I deliberately made them excessively low, painted them with black spray paint, then after a few days of driving, noticed where the paint had been scraped off by contact with pavement, curbs, etc., then trimmed away the paint skinned coroplast, repainted, drove some more, trimmed, repeat, until I had everything raised up to a level where they didn't rub the road very often. I keep all of the coroplast on my car that is exposed to direct sunlight painted to keep the sun's ultraviolet from deteriorating the coroplast.

The CX also didn't come with the "rubber" side trim, probably to reduce costs rather than to reduce weight. On my car I covered the indents in the sheet metal where the trim would have gone with coroplast to make the sides smooth and eliminate the small amount of turbulence that those indents would introduce along the sides of the car.

[PaleMelanesian]

On the other hand, Metro found positive results with his temporary air dam down to a ridiculous 2" from the road or something like that.

[j12piprius]

Basjoos, thank you for your detailed reply. Perhaps I used the wrong terminology, as I'm planning to have just a slant back nose, and nothing underneath it, i.e. the plastic nose will serve as a combination grill / nose / and semi airdam depending on the height in the front. I'm not planning to have anything underneath it except space, as that's how The donkey CRX had his for awhile, but might add a bottom later on. The car has a good belly already, so my question is really about the height of the wrap around slant back nose, similar to the front black piece that The donkey CRX uses and the aluminum on the front of Aerohead's truck.

Based on your comment of the solar racing cars, perhaps 8 inches will be fine with the slant back, then focusing on streamlining the smoothness underneath. However, the solar racing cars travel at relatively low speeds, and I wonder if their belly height would be as beneficial up to 70-75 mph, plus I think their bellies are closed off completely. Of course, if I cut the material to 8 inches, then I won't be able to lower it from that point. With the curved around slope, the height could be 6 to 8 inches in the middle, and 4 to 6 inches in front of the tires.

The side trim on my car is made of metal, not rubber. That is interesting that you filled in the indents.

[Istas]

That is some admirable aero work there! And that adjustable intake is ingenious, I don't know why I never thought to use a pre-existing adjustable louver. That may just make it uncomplicated enough for me to feel like trying out.

[basjoos]

Some of World Solar Challenge runs in Australia have averaged speeds over 60 mph (won by the Nuna 3 and the Tokai Challenger) and some of the cars are capable of sprinting to speeds over 90 mph.

If you are going to install a slant back nose to lower the stagnation point and already have a smooth underbelly, then an air dam likely won't do much to reduce your drag given its attendant increase in frontal area since you have already cleaned up the areas under the car that the air dam deflects the wind away from. But you would just have to experiment and see what your results are. On my car I have a rounded nose which extends forward and downwards the curving slope of the hood and has a profile like the front of an airfoil.

[The donkey CRX]

I agree that the "Mad Max" type air dam on the front of my VX is more or less a "down and dirty" solution as you stated. I am convinced that if we had done one more like yours we would have seen even more aero benefit.

We plan to do either another VX or a CRX next and I would like the front to be more like yours for all the advantages you stated above. I'm just happy that even our compromised aero package has improved MPG by about 9 or 10 MPG.

As far as collecting wildlife with the "Mad Max" air dam, you are so right. I don't even try to keep the bug hits cleaned off in the spring.

Yesterday as I was going in to the shop, I came upon a recently killed Armadillo in the middle of the road with one front leg sticking up. As I passed over him he "High Fived" my air dam. I thought that showed a great attitude on his part.

[The donkey CRX]

Thanks for your kind words.

Actually, both of the adjustable shutters were handmade from 1/16 inch flat aluminum sheet material. They are different because they are early prototypes. We are using the one on the passenger side as our current design .

But you are correct that a residential A/C register from Lowes can be used for this purpose as the picture below shows. Unfortunately this one was made from very thin steel and froze up from rust after only a few months.



By the way, This is a picture of the ORIGINAL Donkey CRX that Ecotex found. Notice it also has Lowes flower bed edging as the air dam material. It improved MPG by about 4 MPG.

[Istas]

Ah, my mistake. The design looked regular enough that I thought it was a vent purchased off the shelf. And thanks for the tip on that too; if I get one from a hardware store I'll look for one that's aluminum, or rated for outdoor use, or something along those lines.

[NeilBlanchard]

Your fuel log continues to be impressive! I hope this project gets added to the front page rotation.