Civic hatchback aerodynamics

[Danronian]

Wow. Looks like it was really planned out. It came together nicely this time around.

[Nerds laugh at me]

I wish I had the balls to do something like this.
Basjoos -I'm really impressed !


I wanted to ask about your grill setup. You say that the engine takes in air from the hood slot since you removed some of the weatherstrip there.
Other than removing the weatherstriping, did you raise the radiator or do any other sort of mods? What does the temperature guage read ?
Thanks a lot for sharing the info.

I also wanted to ask what advantage that adding the spike nose has to the car.
I notice that there are plenty of cars that not only have blunt front ends - but almost a brick like shape to the front end ( the Ford Fusion that was posted here that has a .21 Cd, the Opel G90 at .22 Cd ( and both of these cars have no boat tail or wheel covers) as well as the new Cadillacs.
At subsonic speeds, from what I have read a rounded front end is more efficient.
Just asking ( educate me ;-) ! )

I read that a steep windshield is just for looks once it passes a 45 * angle.
This info was from the guy that did the aerodynamics on the EV1.
So what advantage did the extended winshield have ?

Thanks !
I appreciate your hard work and any info you share with us !

[basjoos]

Originally Posted by AmmoCatcher

How'd you get the Lexan to bend without breaking/crazing? I'm wanting to do something similar with my del Sol and haven't got the nerve up to do it yet.

You can bend Lexan with a metal brake. I used 1/8" Lexan, which is easy enough to bend into place with the application of some body english and then secure with screws.

[basjoos]

Originally Posted by jwxr7

that looks really good . . Does your middle upper brake light still shine thru good? I know in michigan that could get a car pulled over. We don't need any more excuses to get pulled over.

No problem seeing the middle brake light.

[thisisntjared]

i love it! keep it up. it looks a lot better now!

[basjoos]

[QUOTE=Nerds laugh at me;74126]
I wanted to ask about your grill setup. You say that the engine takes in air from the hood slot since you removed some of the weatherstrip there.
Other than removing the weatherstriping, did you raise the radiator or do any other sort of mods? What does the temperature guage read ?
Thanks a lot for sharing the info.

I also wanted to ask what advantage that adding the spike nose has to the car.
I notice that there are plenty of cars that not only have blunt front ends - but almost a brick like shape to the front end ( the Ford Fusion that was posted here that has a .21 Cd, the Opel G90 at .22 Cd ( and both of these cars have no boat tail or wheel covers) as well as the new Cadillacs.
At subsonic speeds, from what I have read a rounded front end is more efficient.
Just asking ( educate me ;-) ! )

I read that a steep windshield is just for looks once it passes a 45 * angle.
This info was from the guy that did the aerodynamics on the EV1.
So what advantage did the extended winshield have ?
QUOTE]

The radiator is in its stock position. The top of the radiator sticks up above the level of the hood slot and scoops the incoming air down in front of it so it can pass through the rest of the radiator. I've never never had any overheating problems with the current setup dispite this summer's 103F highs. The temp needle has never climbed above its usual location of the gauge, which it did with some of my earlier experiments at grill blocking.

All I know is that when I added the nosepiece, it coasted better and it reduced the size of the A pillar vortex by about half. This was in my pre-SuperMID days, so I don't have an exact MPG figure for it. I based its shape on that of modern aircraft noses, none of which are brick shaped, and all of whose Cd is well below that 0.20 figure that the car designers are aiming at.

The extended windshield eliminated the A pillar vortex completely and also the high pressure zone at the base of the stock windshield. This high pressure is what pushes air through your air vents when the fan isn't running and some performance cars have a raised hood open to the base of the windshield that uses this high pressure air for engine intake air. I based the shape of my extended windshield on the windshields of modern composite aircraft, such as the Cirrus SR20. I plan to re-glaze the extended windshield with Lexan and then do some tests with and without it.

[Nerds laugh at me]

Thanks basjoos !
Looks like your experiments are helping us all !
Much appreciated !
I need those happy face icons so you guys read my comments in the right tone.
When I said that stuff about the winshield angle and nose cone ( as well as some other comments I have made in the past ) I was in an inquisitive tone.
I'd like everyones opinion. I'm just asking because I see a lot of conflicting stuff.
Here is some Photoshop doodles. I hope you don't mind me drawing all over your car.
What would look better in my opinion would be to black out certain areas using flat black paint. Gloss would show the dents toowell and run - as well as look cheap. Flat( matte) would have a more professional look to it.
You could do it with spray cans and if you wet sanded it afterwards with superfine grit wet-dry sandpaper, it would get rid of the spray can look that makes a car look awful.
As far as those air deflectors n the sides and on the top, they would help shape the cars profile to something more ... racy but would be fully functional.
In fact, MetroMPG added some on his test with wheel covers and they increased the MPG percentage quite a bit !
I have planned to have these on my car for years, but have just chickened out - and besides iwas not sure if 'squeezing the air into a smaller wake would work .
Apparently it does !!
As far as the fins on the top, they would help to cut the phallic look of the back end and ..yup they too would be functinal by pinching the air into a smaller wake as well as channeling the air like a vertical stabilizer on an aircraft.
Also they look racy. Many Top fuel funny cars have these ( although inbetween the vertical stabililizers is a wing to create downforce - something you could omit.
The arrow in the image points to a car called 'Blowfish' that Hot Rod built to run at Bonneville. Note the tail.
Let me know what you think !

Something I have been wanting to ask you from the start of all of this ..of all the things on a car that are not needed, why do you still have your radio antenna out in the breeze ??
I removed mine and only noted a slight difference in reception. I pushed it down into the antenna hole and had it make contact with the metalbody - acting as a huge antenna itself.
Strangely enough even the tiny wire that serves as an antenna has a small effect on your ,Cd ( Besides there is the base which stick up about a quarter inch. Why not flatten that sucker out ?

[Nerds laugh at me]

Duh might help if I added the pictures

[McPatrick]

That is simply awsome! If this starts looking any more professional you can start selling aftermarket kits for Civic Hatchbacks

Do you detect any difference in mpg between the old and new boat tail?

[brucepick]

Basjoos, you're an inspiration to us all!
Your work shows what CAN be done if the designers would just DO IT.

Count me as another one here wishing I had the um, cajones, to do a real boattail and nose treatment. A moderate nose job is currently in the works for Sven. Not an extended nose, but it should be better than the current one. I'll share pics when I get it in place.